Long-range air dispersion of Candida auris in a cardiothoracic unit outbreak in Hong Kong.

BACKGROUND: Nosocomial outbreaks of Candida auris, a multidrug-resistant fungus, are increasingly reported worldwide; the mode of transmission has usually been reported to be via direct contact. Some studies previously suggested potential short-distance air dispersal during high-turbulence activities, but evidence on long-range air dispersal remains scarce. AIM: To describe a C. auris nosocomial outbreak involving two wards (H7, 5E) in two local hospitals. METHODS: Samples were taken from patients, ward surfaces (frequently touched items and non-reachable surfaces) while settle plates were used for passive air sampling to investigate possible contributions by direct contact and air dispersal. Epidemiological and phylogenetic analyses were also performed on the C. auris isolates from this outbreak. FINDINGS: Eighteen patients were confirmed to have asymptomatic C. auris skin colonization. C. auris was expectedly identified in samplings from frequently touched ward items but was also isolated in two samples from ceiling supply air grilles which were 2.4 m high and inaccessible by patients. Moreover, one sample from a corridor return air grille as far as 9.8 m away from the C. auris cohort area was also positive. Two passive air samplings were positive, including one from a cubicle with no confirmed cases for four days, suggesting possible air dispersal of C. auris. Whole-genome sequencing confirmed clonality of air, environment, and patients' isolates. CONCLUSION: This is the first study to demonstrate potential long-range air dispersal of C. auris in an open-cubicle ward setting. Ventilation precautions and decontamination of out-of-reach high-level surfaces should be considered in C. auris outbreak management.

Effect of SARS and COVID-19 outbreaks on urology practice and training.

INTRODUCTION: The objective was to investigate the changes in urology practice during coronavirus disease 2019 (COVID-19) pandemic with a perspective from our experience with severe acute respiratory syndrome (SARS) in 2003. METHODS: Institutional data from all urology centres in the Hong Kong public sector during the COVID-19 pandemic (1 Feb 2020-31 Mar 2020) and a non-COVID-19 control period (1 Feb 2019-31 Mar 2019) were acquired. An online anonymous questionnaire was used to gauge the impact of COVID-19 on resident training. The clinical output of tertiary centres was compared with data from the SARS period. RESULTS: The numbers of operating sessions, clinic attendance, cystoscopy sessions, prostate biopsy, and shockwave lithotripsy sessions were reduced by 40.5%, 28.5%, 49.6%, 44.8%, and 38.5%, respectively, across all the centres reviewed. The mean numbers of operating sessions before and during the COVID-19 pandemic were 85.1±30.3 and 50.6±25.7, respectively (P=0.005). All centres gave priority to cancer-related surgeries. Benign prostatic hyperplasia-related surgery (39.1%) and ureteric stone surgery (25.5%) were the most commonly delayed surgeries. The degree of reduction in urology services was less than that during SARS (47.2%, 55.3%, and 70.5% for operating sessions, cystoscopy, and biopsy, respectively). The mean numbers of operations performed by residents before and during the COVID-19 pandemic were 75.4±48.0 and 34.9±17.2, respectively (P=0.002). CONCLUSION: A comprehensive review of urology practice during the COVID-19 pandemic revealed changes in every aspect of practice.

Mechanisms for oscillatory true polar wander.

Palaeomagnetic studies of Palaeoproterozoic to Cretaceous rocks propose a suite of large and relatively rapid (tens of degrees over 10 to 100 million years) excursions of the rotation pole relative to the surface geography, or true polar wander (TPW). These excursions may be linked in an oscillatory, approximately coaxial succession about the centre of the contemporaneous supercontinent. Within the framework of a standard rotational theory, in which a delayed viscous adjustment of the rotational bulge acts to stabilize the rotation axis, geodynamic models for oscillatory TPW generally appeal to consecutive, opposite loading phases of comparable magnitude. Here we extend a nonlinear rotational stability theory to incorporate the stabilizing effect of TPW-induced elastic stresses in the lithosphere. We demonstrate that convectively driven inertia perturbations acting on a nearly prolate, non-hydrostatic Earth with an effective elastic lithospheric thickness of about 10 kilometres yield oscillatory TPW paths consistent with palaeomagnetic inferences. This estimate of elastic thickness can be reduced, even to zero, if the rotation axis is stabilized by long-term excess ellipticity in the plane of the TPW. We speculate that these sources of stabilization, acting on TPW driven by a time-varying mantle flow field, provide a mechanism for linking the distinct, oscillatory TPW events of the past few billion years.

Membrane-type acoustic metamaterial with negative dynamic mass.

We present the experimental realization and theoretical understanding of a membrane-type acoustic metamaterial with very simple construct, capable of breaking the mass density law of sound attenuation in the 100-1000 Hz regime by a significant margin ( approximately 200 times). Owing to the membrane's weak elastic moduli, there can be low-frequency oscillation patterns even in a small elastic film with fixed boundaries defined by a rigid grid. The vibrational eigenfrequencies can be tuned by placing a small mass at the center of the membrane sample. Near-total reflection is achieved at a frequency between two eigenmodes where the in-plane average of normal displacement is zero. By using finite element simulations, negative dynamic mass is explicitly demonstrated at frequencies around the total reflection frequency. Excellent agreement between theory and experiment is obtained.

Sequence confirmation of the EWS-WT1 fusion gene transcript in the peritoneal effusion of a patient with desmoplastic small round cell tumor.

Desmoplastic small round cell tumor (DSRCT) is a rare undifferentiated neoplasm. The prognosis is poor, even if therapy is instituted promptly, and thus it is important to differentiate it from other histologically and cytologically similar-looking malignancies of the young adult. We present a case of DSRCT in a 17-yr-old male with disseminated peritoneal disease and peritoneal effusion. The cytology sample showed a malignant small round cell tumor, the classical cytological features of DSRCT, and immunohistochemistry performed in the prepared cell block exhibited an antibody expression profile in keeping with DSRCT. Further material from the effusion was prepared for RNA extraction, following which a reverse-transcriptase polymerase chain reaction (RT-PCR) and sequencing of the t(11;22)(p13;q11 or q12) were carried out. The result showed the presence of the reciprocal translocation and thus confirmed the diagnosis of DSRCT. This case shows how molecular techniques (including sequencing) can be applied to cytology in clarifying and confirming certain difficult diagnosis of undifferentiated neoplasms, DSRCT in this particular case.

A comparison of linear and nonlinear statistical techniques in performance attribution.

Performance attribution is usually conducted under the linear framework of multifactor models. Although commonly used by practitioners in finance, linear multifactor models are known to be less than satisfactory in many situations. After a brief survey of nonlinear methods, nonlinear statistical techniques are applied to performance attribution of a portfolio constructed from a fixed universe of stocks using factors derived from some commonly used cross sectional linear multifactor models. By rebalancing this portfolio monthly, the cumulative returns for procedures based on standard linear multifactor model and three nonlinear techniques-model selection, additive models, and neural networks-are calculated and compared. It is found that the first two nonlinear techniques, especially in combination, outperform the standard linear model. The results in the neural-network case are inconclusive because of the great variety of possible models. Although these methods are more complicated and may require some tuning, toolboxes are developed and suggestions on calibration are proposed. This paper demonstrates the usefulness of modern nonlinear statistical techniques in performance attribution.

Perforation of the jejunum secondary to AIDS-related gastrointestinal Kaposi's sarcoma.

Intestinal perforation in human immunodeficiency virus-positive patients due solely to Kaposi's sarcoma (KS) has rarely been described. A homosexual man with acquired immunodeficiency syndrome-related KS who presented with an acute abdomen is presented. He was found to have a jejunal perforation through a small KS lesion. There were no infectious organisms identified at the site of perforation.

Human immunodeficiency virus infection, the acquired immunodeficiency syndrome, and inflammatory bowel disease.

The objective of this study was to determine the effect of human immunodeficiency virus (HIV) infection/acquired immunodeficiency syndrome (AIDS) on inflammatory bowel disease (IBD). A retrospective survey of the medical records of St. Paul's Hospital and its AIDS-care physicians/gastroenterologists searching for patients with both HIV/AIDS and IBD was conducted. Of 1,839 hospitalized patients (4,459 hospital admissions) from 1989 to 1993, two patients with AIDS/HIV and IBD were found. The physician survey revealed four patients for a total of six patients. Four patients developed de novo IBD--two ulcerative colitis (UC), one Crohn's disease (CrD), and one indeterminate colitis (IC)--after HIV infection. Two patients had UC predating HIV seroconversion. The absolute CD4 count of patients with de novo IBD was 210-700 cells/ml at the time of IBD. The patient with IC maintained quiescent IBD from a CD4 count of 190-30 cells/ml. The other had many relapses before HIV seropositivity. With CD4 count depletion, disease activity improved. IBD medications were discontinued at a CD4 count of 130 cells/ml. Diarrhea returned at a CD4 count of 20 cells/ml; however, sigmoidoscopy was unremarkable, and mucosal biopsy revealed cryptosporidiosis without active UC. No patient had an AIDS-related illness during active IBD. Two patients followed to CD4 counts of < 30 cells/ml suffered AIDS-related infections with quiescent IBD. With a progressive decline in CD4 count, IBD disease activity may improve and remit. The CD4 count at which remission occurs may reflect severe immunodeficiency such that risk for AIDS-related infection is high. Active IBD may occur with lesser degrees of immunodeficiency.

Fine-needle aspiration diagnosis of extrapulmonary Pneumocystis carinii lymphadenitis in a human immunodeficiency virus positive patient.

Extrapulmonary Pneumocystitis carinii is an uncommon and probably underdiagnosed complication of pulmonary P. carinii infections. We report the cytologic diagnosis of a case of P. carinii lymphadenitis which presented, without concurrent or historical pneumonitis, in a human immunodeficiency virus (HIV) positive patient who was taking aerosolized pentamidine. The diagnosis was suggested by abundant granular exudate on the cell block. Only scant, fragmented, irregular-shaped granular exudate was present on the direct smears and the Millipore filter preparation. The diagnosis was confirmed by special stains on the cell block.

MR imaging of adrenal masses: value of chemical-shift imaging for distinguishing adenomas from other tumors.

OBJECTIVE: CT and conventional MR imaging are helpful in characterizing adrenal tumors, but a specific diagnosis is not achieved for a substantial number of lesions. Chemical-shift imaging relies on the different resonance frequencies of protons in water and triglyceride molecules and therefore may permit a more specific diagnosis of adrenal adenomas, which are known to contain abundant lipid. The purpose of this study was to evaluate the usefulness of chemical-shift MR imaging in the differentiation of adrenal adenomas from other adrenal masses. SUBJECTS AND METHODS: Forty-one adrenal masses (17 nonhyperfunctioning adenomas, two aldosteronomas, six pheochromocytomas, one ganglioneuroma, five adrenal carcinomas, one lymphoma, seven metastases, one case of extramedullary hematopoiesis, and one leiomyosarcoma) suspected clinically or identified by sonography or CT in 38 patients were prospectively evaluated with MR imaging. Pathologic proof of diagnosis was obtained for 28 lesions, and stability on imaging follow-up (mean, 19 months) was accepted as proof of diagnosis of benign adenoma for 13 lesions. In-phase T1-weighted spin-echo sequences (500/20 [TR/TE]) and opposed-phase gradient-echo sequences (142/6.3, flip angle = 90 degrees) of the adrenal regions were applied. Quantitative analysis of signal intensity loss in the adrenal lesions relative to reference tissues (liver, muscle, and spleen) on in-phase and opposed-phase sequences was done to differentiate adenomas from nonadenomas. Region-of-interest signal intensity measurements were obtained in a standard fashion by selection of the largest possible representative sample. RESULTS: Using liver as the reference standard, we found that mean signal intensity ratios were 0.47 (range, 0.23-0.97) for adrenal adenomas and 0.88 (range, 0.65-1.32) for nonadenomas; signal intensity ratios for two adenomas overlapped those of the nonadenomas. Using muscle as the reference standard, we found that mean signal intensity ratios were 0.44 (range, 0.22-0.66) for adrenal adenomas and 0.85 (range, 0.59-1.39) for nonadenomas; signal intensity ratios for two adenomas overlapped those of the nonadenomas. Using spleen as the reference standard, we found that mean signal intensity ratios were 0.45 (range, 0.27-0.73) for adrenal adenomas and 0.97 (range, 0.8-1.18) for nonadenomas, with no overlap. The mean signal intensity ratios were significantly different between adenomas and nonadenomas for all three reference tissues (p < .001). CONCLUSION: Our results show that chemical-shift MR imaging is an important new technique that enables the differentiation of adrenal adenomas from other adrenal masses, reducing the need for biopsy and prolonged imaging follow-up in patients with adrenal tumors.

Solid breast lesions: diagnosis with US-guided fine-needle aspiration biopsy.

PURPOSE: To ascertain the usefulness of real-time ultrasound (US)-guided fine-needle aspiration biopsy as an adjunct to clinical, mammographic, and sonographic assessment of solid breast lesions. MATERIALS AND METHODS: US-guided fine-needle aspiration biopsy was performed in 225 malignant and 580 benign solid breast lesions confirmed by means of excisional biopsy or with imaging follow-up (mammography or US) performed at approximate intervals of 6, 12, 24, and 36 months. All lesions were classified as palpable or nonpalpable at clinical examination and visible or nonvisible on mammograms. RESULTS: In 213 malignant lesions (95%), the cytologic findings were malignant or suspicious, with no false-positive and 12 false-negative cases. Mammography did not enable detection of 58 cancers (26%), 43 of which were palpable. Fifteen cancers discovered with US were nonpalpable and not seen on mammograms. Cytologic diagnosis of fibroadenoma or nonspecific benign cells was correct in 535 lesions. The sensitivity of this method was 95%; specificity, 92%; and overall accuracy, 93%. CONCLUSION: Real-time US-guided fine-needle aspiration biopsy is a useful adjunct to clinical, mammographic, and sonographic assessment of solid breast lesions.

Surgical management of pneumothorax in patients with acquired immunodeficiency syndrome.

Pneumocystis carinii pneumonia in a patient with acquired immunodeficiency syndrome may cause severe alveolar damage, resulting in pneumothoraces that are often bilateral, recurrent, and refractory to accepted methods of treatment. The clinical features, management, and follow-up results were assessed in 22 consecutive patients who presented with a pneumothorax and acquired immunodeficiency syndrome. Seventeen patients died within the time frame of this study. Their average survival time was 147 days. Five surviving patients have lived an average of 366 days. We proposed an algorithm to assist in the management of pneumothoraces in these patients. We concluded that pneumothorax in patients with acquired immunodeficiency syndrome is prognostic of short-term survival. The results in the treatment of pneumothorax in the patient with acquired immunodeficiency syndrome are related to the pathologic lesions of the lung that are associated with Pneumocystis pneumonia and not to the surgical treatment that is employed.

Malignant primary cardiac tumour presenting as superior vena cava obstruction syndrome.

A 71-year-old male with a malignant primary cardiac lymphoma nearly filling the right atrium presented with symptoms of obstruction of the tricuspid valve and inflow to the right atrium. The tumour was resected as fully as possible; however, a portion of the tumour that had invaded the inferior aspect of the right atrium and the atrioventricular groove could not be excised. Eighteen months after initial presentation, the patient is well and the tumour has not recurred. This is the first case of symptom-free survival of primary cardiac lymphoma for as long as 18 months.

Fine needle aspiration cytology in the evaluation of head and neck masses.

One hundred eighty-two fine needle aspirations (FNAs) of head and neck masses performed between the years 1981 and 1987 were studied retrospectively. Seventeen FNAs were unsatisfactory. Of the remaining 165, 148 (90%) were followed up with either surgery or clinical follow-up of at least 12 months' duration. Seventy-one of these aspirates were malignant. Fifty-six cases of metastatic carcinoma and 13 cases of lymphoma were diagnosed. The positive predictive value for metastatic carcinoma and lymphoma was 100%, and the sensitivities were 92% and 100%, respectively. For benign salivary gland lesions, the positive predictive value was 94%, whereas for malignant lesions it was 100%. One case of carcinoma ex-pleomorphic adenoma was missed by FNA. No complications were associated with FNA. We conclude that FNA is a safe and accurate technique, well suited to the in-office evaluation of neck masses of differing causes.

Palpable prostatic nodules: comparison of US and digital guidance for fine-needle aspiration biopsy.

This study was undertaken to evaluate the use of transrectal sonographically guided fine-needle aspiration biopsy and to compare sonographic with digital guidance for biopsy. In 62 patients in whom prostatic carcinoma was suspected at digital rectal examination, fine-needle aspiration biopsies were performed transperineally under sonographic guidance and transrectally under digital guidance. These patients had 89 nodules, 73 of which were sampled with both techniques. Malignant cells were obtained under digital guidance in 17 of 73 nodules (23%) and under sonographic guidance in 16 (22%). An additional seven nodules, which were not seen sonographically, were sampled under digital guidance and proved to be negative. In nine other nodules that were nonpalpable and evident only with sonography, malignant cells were obtained under sonographic guidance in three. These findings indicate that sonographic guidance for fine-needle aspiration biopsy is as good as digital guidance for palpable lesions.

Combined biopsy techniques: an approach to the diagnosis of prostatic malignancy.

We present our results of 3 biopsy techniques applied to each of 62 patients with clinically suspicious prostatic nodules. Transrectal digitally guided and sonographically guided transperineal fine needle aspiration biopsies were followed by digitally guided transperineal core biopsy in all cases. Adenocarcinoma was confirmed in 25 patients by 1 or more of these techniques. Our results indicated that 7 of 25 cancer cases (28 per cent) were detected by only 1 of 3 applied methods of biopsy and 56 per cent were detected by all 3 techniques. When a clinical suspicion of malignancy remains after a negative aspiration or core biopsy consideration should be given to alternative forms of biopsy to establish a diagnosis.