Simulating a Mott Insulator Using Attractive Interaction.

We study the particle-hole symmetry in the Hubbard model using ultracold fermionic atoms in an optical lattice. We demonstrate the mapping between charge and spin degrees of freedom and, in particular, show the occurrence of a state with "incompressible" magnetization for attractive interactions. Our results present a novel approach to quantum simulation by giving access to strongly correlated phases of matter through an experimental mapping to easier detectable observables.

Antiferromagnetic Correlations in Two-Dimensional Fermionic Mott-Insulating and Metallic Phases.

We experimentally study the emergence of antiferromagnetic correlations between ultracold fermionic atoms in a two-dimensional optical lattice with decreasing temperature. We determine the uniform magnetic susceptibility of the two-dimensional Hubbard model from simultaneous measurements of the in situ density distribution of both spin components. At half filling and strong interactions our data approach the Heisenberg model of localized spins with antiferromagnetic correlations. Moreover, we observe a fast decay of magnetic correlations when doping the system away from half filling.

Thermodynamics versus Local Density Fluctuations in the Metal-Mott-Insulator Crossover.

The crossover between a metal and a Mott insulator leads to a localization of fermions from delocalized Bloch states to localized states. We experimentally study this crossover using fermionic atoms in an optical lattice by measuring thermodynamic and local (on-site) density correlations. In the metallic phase at incommensurable filling we observe the violation of the local fluctuation-dissipation theorem indicating that the thermodynamics of the system cannot be characterized by local observables alone. In contrast, in the Mott insulator we observe the convergence of local and thermodynamic fluctuations indicating the absence of long-range density-density correlations.

Wilson Sims Fall Risk Assessment Tool Versus Morse Fall Scale in Psychogeriatric Inpatients: a Multicentre Study.

OBJECTIVE: To compare predictive validity of the Wilson Sims Fall Risk Assessment Tool (WSFRAT) with that of the Morse Fall Scale (MFS) in psychogeriatric inpatients. METHODS: Psychogeriatric patients from Shatin Hospital, Tai Po Hospital, Castle Peak Hospital, and United Christian Hospital who had fall incident between April 2019 and April 2020 were identified. Their fall risks were assessed by the WSFRAT and the MFS, and their falls incidents during hospitalisation were recorded. Patients were classified as having high fall risk when their MFS score was ≥45 and when their WSFRAT score was ≥7. Sensitivity, specificity, and positive and negative predictive values of the two scales were calculated. RESULTS: We identified 183 (90 male and 93 female) psychogeriatric patients aged ≥65 years who had fall incident and were assessed by both the WSFRAT and the MFS during the study period. Among the 183 patients, four sustained a fall during hospital stay, giving a prevalence of 2.19%. All four patients were classified as having high risk of fall by WSFRAT, but only two of them were classified so by MFS. The sensitivity of WSFRAT was 100%, which was higher than the 50% by MFS, but specificity of MFS was higher than that of WSFRAT (45.81% vs 54.75%). CONCLUSION: WSFRAT is a better fall risk assessment scale for psychiatric inpatients than MFS, because of higher sensitivity (100% vs 50%). It has items specific to psychiatric patients and should replace MFS in psychiatric settings.

Hepatocyte-specific activation of NF-kappaB does not aggravate chemical hepatocarcinogenesis in transgenic mice.

The NF-kappaB signalling pathway plays important roles in liver organogenesis and carcinogenesis. Mouse embryos deficient in IKKbeta die in mid-gestation, due to excessive apoptosis of hepatoblasts. Although activation of the NF-kappaB signalling pathway has been demonstrated in human hepatocellular carcinoma, the role of NF-kappaB is controversial. Here, we have generated transgenic mice in which a constitutively active form of IKKbeta was expressed in a hepatocyte-specific manner. Using electrophoretic mobility shift assay, we documented increased NF-kappaB activities and up-regulated levels of NF-kappaB downstream target genes, Bcl-xL and STAT5, in the transgenic mouse livers. These results confirmed that the NF-kappaB pathway was activated in the livers of the transgenic mice. However, there was no significant difference in tumour formation between transgenic and wild-type mice up to an age of 50 weeks. When we treated the transgenic mice with the chemical carcinogen diethylnitrosamine (DEN), we observed no significant differences in the incidence and size of liver tumours formed in these mice with and without DEN treatment at 35 weeks of age, suggesting that the activated NF-kappaB pathway in the livers of the transgenic mice did not enhance hepatocarcinogenesis. Interestingly, some of the transient transgenic embryos (E12.5) had abnormal excessive accumulation of nucleated red blood cells in their developing livers. In summary, NF-kappaB activation in hepatocytes did not significantly affect chemical hepatocarcinogenesis. In addition, the TTR/IKKCA transgenic mice may serve as a useful model for studying the role of NF-kappaB activation in hepatocarcinogenesis as well as inflammatory and metabolic diseases.

Six-month Follow-up of Cognitive Impairment and Depressive Symptoms in Late-onset Depression.

OBJECTIVE: To assess cognitive performance in elderly depressed patients following treatment for 6 months. Remission rate of depression after 6 months of treatment was calculated. METHODS: The study was performed in a consecutive group of patients aged ≥ 65 years with late-onset depression. Severity of depression was assessed by the Hamilton Depression Scale, cognitive performance by the Hong Kong Montreal Cognitive Assessment, and functional level by the Instrumental Activities of Daily Living Scale. RESULTS: A total of 52 patients were recruited. In all, 28 (53.8%) were found to have cognitive impairment at baseline and 8 (28.6%) of them had improvement after 6 months. This cognitively impaired group was older and had a lower Instrumental Activities of Daily Living Scale score. The remission rate of depression was 61.5%. CONCLUSIONS: Cognitive impairment constituted a stable feature in a considerable number of elderly patients with depression. About two-thirds of patients achieved remission of depression after 6 months of treatment.

Hepatitis C virus antibody in multiply transfused Chinese with thalassaemia major.

Thirty-four of 99 multiply transfused Chinese (49 females, 50 males) with thalassaemia major were positive for antibody to hepatitis C virus. There was no sex predominance in seropositivity with 18 females and 16 males positive. The mean (+/- SD) age and units of blood transfused were significantly higher in the seropositive patients (167 +/- 48 months, 206 +/- 82 units respectively) than the seronegative patients (113 +/- 56 months, 124 +/- 80 units respectively). The seropositive patients had higher mean (+/- SD) serum alanine aminotransferase, aspartate aminotransferase and ferritin concentrations (91 +/- 82 IU/L, 67 +/- 38 IU/L, 4797 +/- 2522 ng/ml respectively) than the seronegative patients (38 +/- 29 IU/L, 48 +/- 28 IU/L, 3620 +/- 2140 ng/ml respectively). Serum ferritin had an independent and significant effect on serum alanine aminotransferase in addition to that of seropositivity to hepatitis C virus.

Mixed chimerism following bone marrow transplantation for severe combined immunodeficiency: a study by DNA fingerprinting and simultaneous immunophenotyping and fluorescence in situ hybridisation.

We report a girl with severe combined immunodeficiency (SCID) who had a paternal T-depleted bone marrow transplant (BMT) when 11 months old. Engraftment was documented but karyotyping of marrow cells 1 year after BMT showed recipient metaphases (XX) only. However, she remained clinically well and further analysis y karyotyping of PHA-cultured peripheral blood mononuclear cells (PBMC) showed donor metaphases (XY) only. DNA fingerprinting confirmed mixed chimerism in the peripheral blood. The granulocytes were of recipient origin and the PBMC of mixed origin, the donor proportion of which increased after culture with PHA. Using simultaneous immunophenotyping and fluorescence in situ hybridisation (FISH) with chromosomes X and Y-specific probes, circulating T cells were demonstrated to be of donor origin whereas B cells and myeloid cells were mostly of recipient origin.

Bone marrow transplantation for thalassemia in Hong Kong: the early experience.

The first experience of bone marrow transplantation (BMT) for thalassemia in Hong Kong is reported. Of the three children transplanted using a matched allogeneic donor, two have been surviving disease free 291 and 256 days post-BMT respectively. The other child rejected the graft and remained transfusion dependent. Mild graft versus host disease occurred in one of the children which subsided on cyclosporin A alone. The regimen-related toxicities were mild and easily manageable. Thus the result is encouraging and the procedure is now accepted as an option of treatment for good risk patients in Hong Kong.

Suramin prevents cerebellar granule cell-death induced by dequalinium.

In this study, we demonstrated that an anticancer drug, dequalinium, a bisquaternary ammonium compound, is a potent neurotoxicant with IC(50) of 0.46 microM on the cultured cerebellar granule neurons. Its selective neurotoxicity revealed by 100-fold more toxic than the other two analogs, pancuronium and vecuronium. The mechanisms underlying dequalinium (DQ)-induced neurotoxicity were explored and found to be associated with decreased mitochondrial membrane potential, increased free radical production and ATP depletion. Suramin (a nonselective purinergic P(2) receptor antagonist and an anticancer drug) but not the glutamate receptor antagonists, MK-801, NBQX (1,2,3,4 tetrahydro-6-nitro-2,3-dioxo-benzo[f]quinoxaline-7-sulfonamide disodium), and DNQX (6,7-dinitroquinoxaline-2,3-dione) significantly prevents the DQ-induced neurotoxicity. By means of microfluorometric image-processing technique using the fluorescent probes, fluorescein diacetate/propidium iodide and Hoechst 33258, respectively, we showed that 1 microM DQ for 24 h induced about 53.5% of apoptosis and 37.5% of necrosis. All of these effects of DQ can be completely prevented by suramin. From these results, we conclude that DQ-induced neurotoxicity was not mediated by glutamate receptor, but by increasing free radical productions and cell energy depletion. Suramin with its beneficial antagonistic effects on DQ-induced neurotoxicity may provide an effective approach for neurodegeneration.

Activation of transcription factors of nuclear factor kappa B, activator protein-1 and octamer factors in hyperalgesia.

Involvement of c-fos and neuronal nitric oxide synthase (nNOS) in the hyperalgesia induced by complete Freund adjuvant (CFA) has been reported. In this paper, we attempted to investigate whether the transcription factors regulating the gene expression of c-fos and nNOS, including activator protein-1 (AP-1), nuclear factor kappa B (NF-kappa B), and octamer factors (Oct), are activated by CFA during the development of hyperalgesia. The electrophoretic mobility shift assay (EMSA) was used to determine whether there were changes in the transcription factors in the lumbar spinal cord of adult rats following subcutaneous injection of CFA in one hindpaw of the rats. Maximum binding of AP-1, NF-kappa B and Oct was found at 0.5, 1 and 2 h after CFA injection, respectively. These findings suggest that the activation of these transcription factors is pivotal for the expression of c-Fos and nNOS proteins, which reached a peak at 3 and 48 h after CFA injection, respectively. The behavioral testing of hyperalgesia demonstrated that CFA reduced the thresholds for mechanical and thermal algesia, reaching a minimum at 6 h. The thresholds had only partially recovered after 96 h. Based on these findings, we conclude that AP-1, NF-kappa B and Oct are crucial for the expression of c-Fos proteins at an early stage (at 3 h) and for the expression of nNOS at a late stage of hyperalgesia (48 h post-injection) induced by CFA.

Hyperhomocysteinaemia and premature coronary artery disease in the Chinese.

OBJECTIVES: To examine the prevalence of hyperhomocysteinaemia and compare it with the classic risk factors and vitamin status in Hong Kong Chinese patients with premature atherosclerotic coronary artery disease. DESIGN: Case-control study. SETTING: General hospital and community. SUBJECTS: Forty five patients (39 males) with significant coronary artery disease confirmed by angiography (32 post myocardial infarction) and 23 healthy volunteers (17 male), all aged less than 55 years. INTERVENTION: Standardised methionine-loading test. MAIN OUTCOME MEASURES: Coronary artery disease, risk factors. RESULTS: More patients than controls had fasting hyperhomocysteinaemia (10/45 v 2/23, P = 0.122), post-methionine hyperhomocysteinaemia (17/45 v 1/23, P = 0.008), and an abnormal response to methionine (15/45 v 1/23, P = 0.015). A history of smoking was more frequent in patients (3/23 v 25/45, P = 0.002). Sixteen of 17 patients with hyperhomocysteinaemia but only nine of 28 with normohomocysteinaemia were smokers (P = 0.0002). Fasting plasma cholesterol concentrations (mean (SD)) were higher in hyperhomocysteinaemic patients (6.41 (1.58) mmol/l) than in controls (5.53 (0.90) mmol/l) (P = 0.042). Serum vitamin B-12 was not reduced and serum folate was higher in hyperhomocysteinaemic patients (35 (4) nmol/l) than normohomocysteinaemic patients (26 (9) nmol/l) (P = 0.009). CONCLUSIONS: Although the prevalence of hyperhomocysteinaemia in Hong Kong Chinese is similar to that in white subjects, hyperhomocysteinaemia is not an independent risk factor for coronary artery disease and is associated with smoking. This may be of some consequence in view of the change to a more Western diet with more animal protein, and therefore methionine, coupled with a high frequency of cigarette smokers in this region. The causes of the hyperhomocysteinaemia are multifactorial but in this pilot study a deficiency of folate and/or vitamin B-12 did not seem to be one of them.

Intracellular calcium and myosin light chain phosphorylation during U46619-activated vascular contraction.

We investigated the relationship between [Ca2+]i, myosin light chain (LC20) phosphorylation and isometric force in guinea pig aortic strips during contractions activated by a thromboxane A2 analogue, (15S)-hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5Z, 13E-dienoic acid (U46619). Isometric force and [Ca2+]i were measured simultaneously using preloaded aequorin as the intracellular calcium indicator. LC20 phosphorylation levels were determined by two dimensional polyacrylamide gel electrophoresis in parallel preparations. Contractions induced by U46619 were accompanied by increases in [Ca2+]i and LC20 phosphorylation. The chelation of extracellular calcium with 2.5 mM EGTA significantly inhibited U46619-induced increases in [Ca2+]i, isometric force and LC20 phosphorylation. Steady-state force assumed a similar dependence on LC20 phosphorylation for contractions stimulated by potassium depolarization, alpha 1-adrenergic agonist phenylephrine and U46619 either in the presence or absence of extracellular calcium. On the contrary, the [Ca2+]i/force relation revealed that both U46619 and phenylephrine stimulated greater isometric force at lower [Ca2+]i than did KCl depolarization. The addition of a protein kinase C inhibitor, 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine (H-7), decreases force without significantly affecting either [Ca2+]i or LC20 phosphorylation levels. These results suggest that in guinea pig aortic smooth muscle U46619 increases the calcium sensitivity of the contractile apparatus but does not change the LC20 phosphorylation/force relation in comparison to K+ depolarization. Protein kinase C is activated during U46619-stimulated contraction and might be involved in mechanisms other than LC20 phosphorylation.

Modified Brooks posterior wiring technique for three-point C1-C2 arthrodesis.

BACKGROUND: The optimal surgical treatment of atlanto-axial instability remains controversial despite the variety of modifications and supplemental techniques currently available. METHODS: We describe a modification of the Brooks posterior wiring technique supplemented with transarticular screws for C1-C2 instability. RESULTS: This method has been implemented in 30 patients in our institution with no radiological failures. CONCLUSIONS: The modification provides several technical advantages and potentially stronger fixation compared to methods currently in use.

Modified arthroscopic suture fixation of displaced tibial eminence fractures using a suture loop transporter.

Current arthroscopic suture fixation techniques of tibial eminence fractures are time consuming and the number of anchor sutures that can be placed is limited by the cumbersome and repetitive numerous needle threading steps. This occurs at 2 stages: first, when placing anchoring sutures through the avulsed anterior cruciate ligament stump with a suture punch, and second, when there is a need to traverse the tibial bone canal with the suture ends. We describe a modification that reduces the reliance on conventional rigid instruments and instead uses a loop transporter made from readily available suture material. The suture loop transporter being malleable reduces the necessary width of the tibial bone canal to be made and has a further advantage of minimizing the bone loss during the reaming of the bone tunnel. The subsequent potential for a stress fracture at these tunnel sites is also substantially reduced. Our technique is more user friendly, more accurate, and quicker to perform.

Remanipulation of forearm fractures in children.

AIMS: To determine whether operator experience or time of operation affects the outcome of fractures of the forearm in the paediatric age group as measured by the need for remanipulation. METHODS: A retrospective analysis of 1155 children with forearm fractures requiring manipulation was undertaken. RESULTS: The remanipulation rate for these 1155 children was 136 or 11.7%. There was a significant difference in those fractures requiring remanipulation dependent upon the experience of the operator and the time of day the procedure was performed. The lowest rate of remanipulation was obtained by senior registrars operating between the hours of 0800-1700 (6/113 or 5.3%). The highest rate was found to be junior registrars between the hours of 1700-2200 (39/167 or 23.3%). It is especially interesting to note the relatively low rate (31/437 or 7.1%) obtained by junior registrars during the night shift (2200-0800 hours). CONCLUSIONS: The current overall remanipulation rate is acceptable. The low rate between 2200-0800 hours means rescheduling of these patients is unnecessary. The rate for junior registrars between 1700-2200 hours needs to be improved.

Acute haemorrhagic conjunctivitis in Hong Kong 1971-1975.

Acute haemorrhagic conjunctivitis occurred in epidemic in Hong Kong in 1971 and 1975 respectively. Two picornaviruses, the Enterovirus type 70 and an antigenic variant of Coxsackie virus type A24, were isolated during the 1971 outbreak, while only the latter virus was detected in the 1975 outbreak. In 1972 and 1974, sporadic cases of conjunctivitis associated with Enterovirus type 70 were observed. Serological survey in late 1975 showed a high proportion of the population might still be susceptible to both viruses. Recrudescence of the disease is conceivable when environmental condition is favourable for the spread of these viruses.

Patients committing suicide whilst under the care of the elderly suicide prevention programme of a regional hospital in Hong Kong.

OBJECTIVE: To examine the risk factors for suicide in elderly Hong Kong Chinese. METHODS: Case notes, mortality reports and hospital records of all the patients, who committed suicide from 1 July 2002 to 31 March 2010 whilst under the active care of the Elderly Suicide Prevention Programme of the Castle Peak Hospital in Hong Kong, were reviewed. RESULTS: A total of 1230 elderly with high risk of suicide were assessed and treated from 1 July 2002 to March 2010. A total of 8 patients in this programme who committed suicide during this period were identified, of whom 63% were male and the most frequent method employed was jumping from a height. All the suicides ensued within the first 6 weeks of treatment under the programme. All these patients were diagnosed to have a depressive illness, and all but 1 had an associated physical illness that possibly precipitated the suicide. They had all been admitted to either a mental or general hospital, about 1 month before committing suicide. CONCLUSIONS: The first 2 months of treatment is associated with the highest risk of suicide. Intensive care and support with proper education about effects of antidepressants, and the building-up of a trusted therapeutic alliance with close relatives are particularly important in this vulnerable period.