Hepatoprotective and antioxidant effects of Wu-Zi-Yuan-Chung-Wan against CCl4-induced oxidative damage in rats

This study was designed to investigate the hepatoprotective potentials of the Wu-Zi-Yuan-Chung-Wan (WZYCW) using an animal model of carbon tetrachloride (CCl4) induced liver injury. CCl4 induced chronic liver hepatotoxicity in adult Sprague-Dawley rats. Excluding the control group, all of the rats with chronic liver fibrosis received 0.4% CCl4 (1.5 mL/kg of body weight, ip) twice per week for 8 weeks. WZYCW (20, 100, and 500 mg/kg) and silymarin (200 mg/kg) were administered five times per week for 8 weeks. After 8 weeks, the rats were sacrificed, blood samples were obtained, and liver histological examinations were performed for subsequent assays. These results suggest that WZYCW considerably reduced Glutamic Oxaloacetic Transaminase (GOT), Glutamic Pyruvic Transaminase (GPT), Triglyceride (TG); and cholesterol activity; and the levels of malonaldehyde (MDA), nitric oxide (NO), and transforming growth factor-β1 (TGF-β1) in the liver. WZYCW also increased the level of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and glutathione reductase (GR) in liver tissue. WZYCW produced hepatoprotective and antifibrotic effects. This is the first study to demonstrate that WZYCW expressed hepatoprotective activity against CCl4 induced acute hepatotoxicity in rat. In addition, the primary compound of WZCYW was analyzed using HPLC. The major peaks of WZCYW, including schizandrin. The results indicate that WZYCW not only enhances hepatic antioxidant enzyme activities and inhibits lipid peroxidation but also suppresses inflammatory responses in CCl4 induced liver damage. Our findings provide evidence that WZYCW possesses a hepatoprotective activity to ameliorate chronic liver injury.

Implementation of a stable, high-power optical lattice for quantum gas microscopy

We describe the design and implementation of a stable high-power 1064 nm laser system to generate optical lattices for experiments with ultracold quantum gases. The system is based on a low-noise laser amplified by an array of four heavily modified, high-power fiber amplifiers. The beam intensity is stabilized and controlled with a nonlinear feedback loop. Using real-time monitoring of the resulting optical lattice, we find the stability of the lattice site positions to be well below the lattice spacing over the course of hours. The position of the harmonic trap produced by the Gaussian envelope of the lattice beams is stable to about one lattice spacing and the long-term (six-month) relative root-mean-square stability of the lattice spacing itself is 0.5%.

Hepatoprotective effect of the ethanol extract of Polygonum orientale on carbon tetrachloride-induced acute liver injury in mice

Polygonum orientale L. (Polygonaceae) fruits have various medicinal uses, but their hepatoprotective effects have not yet been studied. This study investigated the hepatoprotective activity of the ethanolic extract of P. orientale (POE) fruits against carbon tetrachloride (CCl₄)-induced acute liver injury (ALI). Mice were pretreated with POE (0.1, 0.5, and 1.0 g/kg) or silymarin (0.2 g/kg) for 5 consecutive days and administered a dose of 0.175% CCl₄ (ip) on the 5th day to induce ALI. Blood and liver samples were collected to measure antioxidative activity and cytokines. The bioactive components of POE were identified through high-performance liquid chromatography (HPLC). Acute toxicity testing indicated that the LD₅₀ of POE exceeded 10 g/kg in mice. Mice pretreated with POE (0.5, 1.0 g/kg) experienced a significant reduction in their serum aspartate aminotransferase (AST), serum alanine aminotransferase (ALT), and alkaline phosphatase (ALP) levels and reduction in the extent of liver lesions. POE reduced the malondialdehyde (MDA), nitric oxide (NO), tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6) levels, and increased the activity of superoxide dismutase (SOD), glutathione peroxidase (GPx), and glutathione reductase (GRd) in liver. HPLC revealed peaks at 11.28, 19.55, and 39.40 min for protocatechuic acid, taxifolin, and quercetin, respectively. In summary, the hepatoprotective effect of POE against CCl₄-induced ALI was seemingly associated with its antioxidant and anti-proinflammatory activities.

Hepatoprotective effect of Coreopsis tinctoria flowers against carbon tetrachloride-induced liver damage in mice

Background

Coreopsis tinctoria is a traditional remedy for the management of various diseases including hepatitis. The hepatoprotective role of the plant is not scientifically explored till now. This study was designed to investigate the hepatoprotective potentials of the ethanol extract from C. tinctoria (CTEtOH) using an animal model of carbon tetrachloride (CCl₄)-induced acute liver injury.

Methods

CTEtOH (0.5 and 1.0 g/kg) and silymarin (200 mg/kg) were administered to the experimental mice for 7 days followed by 0.2% CCl₄ (10 mL/kg of body weight (bw), ip), then all mice were sacrificed after 24 h. The serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels were measured. Histological analysis of liver was performed. The tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6), nitric oxide (NO), malondialdehyde (MDA), and antioxidant enzymatic activities were also measured..

Results

The results revealed that the serum ALT and AST levels significantly decreased after treatment with CTEtOH. Moreover, histological analyses indicated that CTEtOH (0.5 and 1.0 g/kg) and silymarin reduced the extent of CCl₄-induced liver lesions. CTEtOH (0.5 and 1.0 g/kg) reduced the levels of malondialdehyde, nitric oxide, and proinflammatory cytokines (TNF-α and IL-1β). Furthermore, CTEtOH (1.0 g/kg) reduced the level of IL-6. The activities of antioxidant enzymes, namely superoxide dismutase and glutathione reductase, significantly increased after treatment with CTEtOH (0.5 and 1.0 g/kg) and that of glutathione peroxidase increased after treatment with 1.0 g/kg of CTEtOH.

Conclusions

These results demonstrate the hepatoprotective effect of CTEtOH against CCl₄-induced acute liver injury in mice, and the underlying hepatoprotective mechanisms are associated with antioxidant and antiproinflammatory activities.

Antioxidant and anti-inflammatory activities of aqueous extract of Centipeda minima

ETHNOPHARMACOLOGICAL RELEVANCE

Centipeda minima (L.) is traditionally used in Chinese folk medicine for the treatments of rhinitis, sinusitis, relieving pain, reducing swelling, and treating cancer for a long history in Taiwan. However, there is no scientific evidence which supports the use in the literature.

AIM OF THE STUDY

The aim of this study was to evaluate the antioxidant and anti-inflammatory activities of the aqueous extract of Centipeda minima (ACM).

MATERIALS AND METHODS

The following activities were investigated: antioxidant activities [2,2'-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS), DPPH (1,1-diphenyl-2-picrylhydrazyl)], and anti-inflammatory [lipopolysaccharide (LPS) induced nitric oxide (NO) production in RAW264.7 macrophages and paw-edema induced by λ-carrageenan (Carr)]. We also investigated the anti-inflammatory mechanism of ACM via studies of the activities of catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GPx) and the levels of malondialdehyde (MDA) in the edema paw. Serum NO, tumor necrosis factor α (TNF-α), and interleukin-1β (IL-1β) were also measured in vivo. In HPLC analysis, the fingerprint chromatogram of ACM was established.

RESULTS

ACM showed the highest TEAC and DPPH radical scavenging activities, respectively. ACM also had highest contents of polyphenol and flavonoid contents. We evaluated that ACM and the reference compound of protocatechualdehyde and caffeic acid decreased the LPS-induced NO production in RAW264.7 cells. Administration of ACM showed a concentration dependent inhibition on paw edema development after Carr treatment in mice. The anti-inflammatory effects of ACM could be via NO, TNF-α, and IL-1β suppressions and associated with the increase in the activities of antioxidant enzymes. Western blotting revealed that ACM decreased Carr-induced inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) expressions.

CONCLUSIONS

Anti-inflammatory mechanisms of ACM might be correlated to the decrease in the level of Malondialdehyde (MDA), iNOS, and COX-2 via increasing the activities of CAT, SOD, and GPx in the edema paw. Overall, the results showed that ACM demonstrated antioxidant and anti-inflammatory activity, which supports previous claims of the traditional use for inflammation and pain.

Chemical Compositions, Anti-Inflammatory, Antiproliferative and Radical-Scavenging Activities of Actinidia callosa var. ephippioides

Oxidative stress and inflammation are related to several chronic diseases including cancer. Actinidia callosa var. ephippioides (ACE) is a special folk medicinal plant from Taiwan. The aim of this study is to evaluate the antioxidant, anti-inflammatory, and antiproliferative activities of the methanol extract and fractions from the stem of ACE. Trolox Equivalent Antioxidant Capacity (TEAC), 1,1-Diphenyl-2-picrylhydrazyl (DPPH) scavenging activity, total phenolic content, flavonoid content, inhibition on nitric oxide (NO) productions by LPS-induced RAW264.7 cell, and on lung cancer cell proliferation were employed. Among all fractions, ethyl-acetate fraction (EA-ACE) showed higher TEAC, DPPH radical scavenging activities, polyphenol and flavonoid contents, respectively. EA-ACE also decreased the LPS-induced NO production and expressions of inducible nitric-oxide synthase (iNOS) in RAW264.7 cells. EA-ACE had the highest antiproliferative activity with an IC50 (The concentrations required for inhibition of 50% of cell viability) of 469.17 ± 3.59 μg/mL. Catechin also had good effects in the antioxidant and anti-inflammatory activities. Catechin might be an important bioactive compound in the stem of ACE. The above experimental data indicated that the stem of ACE is a potent antioxidant medicinal plant, and such efficacy may be mainly attributed to its polyphenolic compounds.

Anti-inflammatory activities of aqueous extract of Mesona procumbens in experimental mice

BACKGROUND

Mesona procumbens is consumed as a herbal drink and jelly-type dessert in Taiwan. The aim of this study was to determine the mechanism of anti-inflammatory activities of the aqueous extract of M. procumbens (AMP) using the λ-carrageenin (Carr)-induced mouse paw oedema model. The fingerprint chromatogram of AMP was obtained by high-performance liquid chromatography (HPLC) analysis. To investigate the anti-inflammatory mechanism of AMP, the activities of catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GPx) and the level of malondialdehyde (MDA) in paw oedema were monitored. Serum nitric oxide (NO), tumour necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) were also evaluated.

RESULTS

The fingerprint chromatogram from HPLC indicated that AMP contained protocatechuic acid, chlorogenic acid, vanillic acid and caffeic acid. In the anti-inflammatory test, AMP decreased paw oedema after Carr administration and increased the CAT, SOD and GPx activities and decreased the MDA level in paw oedema at 5 h after Carr injection. AMP also affected the serum NO, TNF-α and IL-1β levels at 5 h after Carr injection. Western blotting revealed that AMP decreased the expression of Carr-induced inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2).

CONCLUSION

Mesona procumbens has the potential to provide a therapeutic approach to inflammation-associated disorders.

Diosgenin ameliorates cognition deficit and attenuates oxidative damage in senescent mice induced by D-galactose

This study attempted to access the neuroprotective effect of diosgenin on the senescent mice induced by d-galactose (D-gal). The mice in the experiments were orally administered with diosgenin (1, 5, 25 and 125 mg/kg), for four weeks from the sixth week. The learning and memory abilities of the mice in Morris water maze test and the mechanism involved in the neuroprotective effect of diosgenin on the mice brain tissue were investigated. Diosgenin (5, 25 and 125 mg/kg, p.o.) showed significantly improved learning and memory abilities in Morris water maze test compared to D-gal treated mice (200 mg/kg, ten weeks). Diosgenin also increased the activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px), and decreased the malondialdehyde (MDA) level in the brain of D-gal treated mice. These results indicated that diosgenin has the potential to be a useful treatment for cognitive impairment. In addition, the memory enhancing effect of diosgenin may be partly mediated via enhancing endogenous antioxidant enzymatic activities.

Esculetin ameliorates carbon tetrachloride-mediated hepatic apoptosis in rats

Esculetin (ESC) is a coumarin that is present in several plants such as Fraxinus rhynchophylla and Artemisia capillaris. Our previous study found that FR ethanol extract (FR_EtOH) significantly ameliorated rats’ liver function. This study was intended to investigate the protective mechanism of ESC in hepatic apoptosis in rats induced by carbon tetrachloride. Rat hepatic apoptosis was induced by oral administration of CCl₄. All rats were administered orally with CCl₄ (20%, 0.5 mL/rat) twice a week for 8 weeks. Rats in the ESC groups were treated daily with ESC, and silymarin group were treated daily with silymarin. Serum alanine aminotransferase (ALT), aspartate aminotransferase (AST) as well as the activities of the anti-oxidative enzymes glutathione peroxidase (GPx), superoxide dismutase (SOD), and catalase in the liver were measured. In addition, expression of liver apoptosis proteins and anti-apoptotic proteins were detected. ESC (100, 500 mg/kg) significantly reduced the elevated activities of serum ALT and AST caused by CCl₄ and significantly increased the activities of catalase, GPx and SOD. Furthermore, ESC (100, 500 mg/kg) significantly decreased the levels of the proapoptotic proteins (t-Bid, Bak and Bad) and significantly increased the levels of the anti-apoptotic proteins (Bcl-2 and Bcl-xL). ESC inhibited the release of cytochrome c from mitochondria. In addition, the levels of activated caspase-9 and activated caspase-3 were significantly decreased in rats treated with ESC than those in rats treated with CCl₄ alone. ESC significantly reduced CCl₄-induced hepatic apoptosis in rats.

Antioxidant, antinociceptive, and anti-inflammatory activities of Xanthii Fructus extract

ETHNOPHARMACOLOGICAL RELEVANCE

Xanthii seeds commonly called Cang-Erzi were used as a traditional Chinese medicine for treating sinusitis, headache due to rheumatism and skin pruritus.

AIM OF THE STUDY

In order to evaluate the actions of this plant, studies were performed on antioxidant, antinociceptive, and anti-inflammatory activities.

MATERIALS AND METHODS

The aqueous extract of Xanthii Fructus (AXF) was evaluated in mice for anti-inflammatory activity using carrageenan-induced hind paw edema model. The antinociceptive activity of AXF was evaluated by writhing and formalin tests. Antioxidant properties were assayed in terms of antioxidant activity by scavenging abilities on 1, 1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid (ABTS), reducing activity and liposome protection. In addition, the total phenolic content was determined with spectrophotometric method.

RESULTS

AXF exhibited significant radical scavenging and reducing activity. And oral treatment with AXF elicited inhibitory activity on acetic acid effect and reduced the formalin effect at the late-phase. In the anti-inflammatory test, AXF inhibited the development of paw edema induced by λ-carrageenan (Carr). AXF decreased the paw edema at the fifth hour after Carr administration, and increased the activities of catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GPx) in the liver tissue and decreased the malondialdehyde (MDA) level in the edema paw. AXF decreased the level of serum nitric oxide (NO) and tumor necrosis factor (TNF)-α after Carr injection and AXF decreased the levels of inducible NO synthase (iNOS) and cyclooxygenase-2 (COX-2) expressions in paw edema at the fifth hour.

CONCLUSIONS

AXF shows antioxidant, antinociceptive, and anti-inflammatory activities, supporting the folkloric usage of the plant to treat various inflammatory diseases.

Yam (Dioscorea pseudojaponica Yamamoto) ameliorates cognition deficit and attenuates oxidative damage in senescent mice induced by D-galactose

This study attempted to access the neuroprotective effect of yam (Dioscorea pseudojaponica Yamamoto) on the senescent mice induced by D-gal. The mice in the experiments were administered orally with yam (20, 100 or 500 mg/kg for 4 weeks, from the sixth week). The learning and memory abilities of the mice in Morris water maze test and the mechanisms involved in the neuroprotective effect of yam on the mice brain tissue were investigated. The content of diosgenin in the yam was also detected by using HPLC. Mice treated with yam were found to significantly improve their learning and memory abilities in Morris water maze test compared to those treated with D-gal (200 mg/kg for 10 weeks). In addition, yam was also found to increase the activities of superoxide dismutase (SOD) and glutathione peroxidase (GPx) and decrease the malondialdehyde (MDA) level on the brains of D-gal treated mice. Finally, the amount of diosgenin in the yam was 5.49 mg/g extract. To sum up, these results indicate that yam had the potential to be a useful treatment for cognitive impairment in TCM. Its beneficial effect may be partly mediated via enhancing endogenous antioxidant enzymatic activities.

Prevalence of hospital infection and antibiotic use at a university medical center in Hong Kong

Hospital infection prevalence surveys were performed in our 1400-bed University medical centre in Hong Kong from 1985 to 1988. We investigated the rates of four major hospital-acquired infections (HAIs) (pneumonia, symptomatic urinary tract infection, surgical site infection and laboratory-confirmed bloodstream infection) in order to identify current distribution and any changes after 15 years. A one-day point prevalence study was performed on 7 September 2005. All inpatients were surveyed for HAIs, community-acquired infections (CAIs), risk factors, pathogenic isolates and antibiotics prescribed. Infections were diagnosed according to Centers for Disease Control and Prevention (CDC) criteria. In total, 1021 patients were surveyed; of these, 41 had 42 HAIs (4% prevalence) and 389 (38%) were receiving antibiotics. The commonest HAI was pneumonia (1.4%) followed by bloodstream infection (0.9%) and symptomatic urinary tract infection (0.8%). The prevalence of postoperative surgical site infection was 5.6%. The nosocomial prevalence rate was highest in the Intensive Care Unit, followed by the Pediatric and Neonatal Intensive Care Units, Children's Cancer Centre/Bone Marrow Transplant Unit and Orthopaedics with Traumatology. Meticillin-resistant Staphylococcus aureus and Pseudomonas aeruginosa were the commonest pathogens. The rates are significantly lower than previously and reflect the increased resources for infection control made available following the outbreak of severe acute respiratory syndrome (SARS).

Behavioral and biochemical characterization of a mutant mouse strain lacking D-amino acid oxidase activity and its implications for schizophrenia

D-amino acid oxidase (DAO) degrades D-serine, a co-agonist at the NMDA receptor (NMDAR). Hypofunction of the NMDAR has been suggested to contribute to the pathophysiology of schizophrenia. Intriguingly, DAO has been recently identified as a risk factor for schizophrenia through genetic association studies. A naturally occurring mouse strain (ddY/DAO-) has been identified which lacks DAO activity. We have characterized this strain both behaviorally and biochemically to evaluate DAO as a target for schizophrenia. We have confirmed that this strain lacks DAO activity and shown for the first time it has increased occupancy of the NMDAR glycine site due to elevated extracellular D-serine levels and has enhanced NMDAR function in vivo. Furthermore, the ddY/DAO- strain displays behaviors which suggest that it will be a useful tool for evaluation of the clinical benefit of DAO inhibition in schizophrenia.

Outcome of infants with right atrial isomerism: is prognosis better with normal pulmonary venous drainage?

OBJECTIVE

To compare the outcome of infants and children who have right atrial isomerism and normal pulmonary venous drainage with those who have anomalous drainage, and to determine factors associated with poor outcome.

DESIGN AND PATIENTS

Retrospective review of management and outcome of 116 infants and children determined to have right atrial isomerism between January 1980 and December 2000.

SETTING

Tertiary paediatric cardiac centre.

RESULTS

The 116 patients presented at a median of one day (range 1 day to 3.7 years) with cyanosis in the majority (96%). No interventions were planned in 31 (27%) patients, all of whom died. The early surgical mortality for pulmonary venous repair was 25% (2 of 8), Fontan procedure 26% (5 of 19), cavopulmonary shunting 7.7% (1 of 13), and systemic pulmonary arterial shunt insertion 1.9% (1 of 53). Late mortality was related to infection (n = 10), sudden death of unknown aetiology (n = 7, 5 with history of arrhythmia), and documented arrhythmia (n = 1). Patients with obstructed anomalous pulmonary venous drainage had the worst survival (p < 0.001). The mean (SEM) survival estimates for those with normal pulmonary venous drainage at 1, 5, 10, and 15 years was 81 (5.3)%, 67 (6.6)%, 60 (7.8)%, and 43 (12)%, respectively, similar to those for patients with non-obstructed anomalous drainage (p = 0.06). Independent risk factors for mortality included pulmonary venous obstruction (relative risk 3.8, p = 0.001) and a single ventricle (relative risk 2.9, p = 0.016). An analysis of only patients with normal pulmonary venous drainage identified no risk factors for mortality.

CONCLUSIONS

The long term outcome of infants and children with right atrial isomerism in association with a normal pulmonary venous drainage remains unfavourable. Sepsis and sudden death that may potentially be related to cardiac arrhythmia are major causes of late mortality.

Analysis of indications for surgical closure of subarterial ventricular septal defect without associated aortic cusp prolapse and aortic regurgitation

Subarterial ventricular septal defect (VSD) is relatively common in Orientals. We reviewed the outcome of 214 patients (137 males) who were followed for 8.6 +/- 5.2 years (range 0.1 to 24.3) and addressed the issue regarding the necessity and optimum timing of closing subarterial defects before development of aortic valve deformities. Demographic data, transthoracic and transesophageal echocardiographic findings, cardiac catheterization results, and operative findings were reviewed. Kaplan-Meier actuarial analysis was performed to assess the development of aortic valve complications over time. Seventy-five patients with heart failure and pulmonary hypertension underwent surgical closure of VSD at the age of 2.4 +/- 2.9 years. No patient had aortic cusp prolapse before operation and none developed aortic cusp prolapse or aortic regurgitation (AR) on follow-up. In contrast, of the 139 asymptomatic patients managed conservatively, 102 (73%) developed aortic cusp prolapse, 78% of whom (80 of 102) developed AR. The prevalence of aortic cusp prolapse and AR at 1, 5, 10, and 15 years old was 8%, 30%, 64%, and 83%, and 3%, 24%, 45%, and 64%, respectively. Significant prolapse or AR prompted surgical closure of VSD with (n = 22) or without (n = 26) valvoplasty in 48 of 102 patients (47%). The size of the VSD was significantly larger in patients with heart failure (9.6 +/- 3.3 mm) or aortic cusp prolapse (11.7 +/- 4.1 mm) compared with those without heart failure (4.5 +/- 1.4 mm, p <0.001). All patients with aortic cusp prolapse and all but 1 with heart failure had a defect size of > or =5 mm. In conclusion, subarterial VSD of > or =5 mm should be closed as early as possible to prevent development of aortic cusp prolapse and AR. Asymptomatic patients with small defects <5 mm could be managed conservatively.

Activation-dependent changes in receptor distribution and dendritic morphology in hippocampal neurons expressing P2X2-green fluorescent protein receptors

ATP-gated P2X(2) receptors are widely expressed in neurons, but the cellular effects of receptor activation are unclear. We engineered functional green fluorescent protein (GFP)-tagged P2X(2) receptors and expressed them in embryonic hippocampal neurons, and report an approach to determining functional and total receptor pool sizes in living cells. ATP application to dendrites caused receptor redistribution and the formation of varicose hot spots of higher P2X(2)-GFP receptor density. Redistribution in dendrites was accompanied by an activation-dependent enhancement of the ATP-evoked current. Substate-specific mutant T18A P2X(2)-GFP receptors showed no redistribution or activation-dependent enhancement of the ATP-evoked current. Thus fluorescent P2X(2)-GFP receptors function normally, can be quantified, and reveal the dynamics of P2X(2) receptor distribution on the seconds time scale.

Observation of self-diffraction by gratings in nematic liquid crystals doped with carbon nanotubes

Diffraction gratings were studied in cells of the homogeneously aligned liquid-crystal E7 doped with multiwall carbon nanotubes. These phase gratings were induced by interference modulation of two coherent optical beams, in conjunction with an applied dc field that was perpendicular to the unperturbed director axis. Self-diffraction was observed at all angles of incidence of the writing beams, including normal incidence. A superior nonlinear-index coefficient of 5x10(-2)cm(2)/W was obtained after passage of a 44-mW/cm(2) beam through a film with a grating constant of 18 mum under an external voltage of 15 V. The observed phenomenon depends strongly on the applied dc field, and the memory effect in a nematic film depends strongly on the grating constant.

Single-molecule measurements calibrate green fluorescent protein surface densities on transparent beads for use with 'knock-in' animals and other expression systems

Quantitative aspects of synaptic transmission can be studied by inserting green fluorescent protein (GFP) moieties into the genes encoding membrane proteins. To provide calibrations for measurements on synapses expressing such proteins, we developed methods to quantify histidine-tagged GFP molecules (His6-GFP) bound to Ni-NTA moieties on transparent beads (80-120 microm diameter) over a density range comprising nearly four orders of magnitude (to 30000 GFP/microm2). The procedures employ commonly available Hg lamps, fluorescent microscopes, and CCD cameras. Two independent routes are employed: (1) single-molecule fluorescence measurements are made at the lowest GFP densities, providing an absolute calibration for macroscopic signals at higher GFP densities; (2) known numbers of His6-GFP molecules are coupled quantitatively to the beads. Each of the two independent routes provides linear data over the measured density range, and the two independent methods agree with root mean square (rms) deviation of 11-21% over this range. These satisfactory results are obtained on two separate microscope systems. The data can be corrected for bleaching rates, which are linear with light intensity and become appreciable at intensities > approximately 1 W/cm2. If a suitable GFP-tagged protein can be chosen and incorporated into a 'knock-in' animal, the density of the protein can be measured with an absolute accuracy on the order of 20%.

Coronary artery fistulas: long-term results of surgical correction

BACKGROUND

Opinions vary as to whether operation should be offered patients with coronary artery fistula, particularly to those who are asymptomatic. Published studies lacked long-term follow-up data.

METHODS

We studied 41 patients with coronary artery fistula operated in our unit in the past 30 years with restudies including coronary angiograms in those who agreed to the investigation.

RESULTS

There was no operative mortality and operative morbidity was low. The mean duration of follow-up was 9.1 years and 96.9% of the patients were asymptomatic. Twenty-one patients had a coronary angiogram. The native coronary artery either remained dilated and tortuous, or more frequently had thromboses with a short proximal stump. (None of these patients had evidence of myocardial ischemia.) Four patients had demonstrable recurrence fistula but without hemodynamic disturbance.

CONCLUSIONS

We advocate operation for all patients with coronary artery fistulas and demonstrable shunting in view of minimal operative risks. Small asymptomatic fistulas without demonstrable shunting should be left alone. The relatively high incidence of residual or recurrent fistula makes long-term follow-up mandatory.

Acoustic field variability induced by time evolving internal wave fields

A space- and time-dependent internal wave model was developed for a shallow water area on the New Jersey continental shelf and combined with a propagation algorithm to perform numerical simulations of acoustic field variability. This data-constrained environmental model links the oceanographic field, dominated by internal waves, to the random sound speed distribution that drives acoustic field fluctuations in this region. Working with a suite of environmental measurements along a 42-km track, a parameter set was developed that characterized the influence of the internal wave field on sound speed perturbations in the water column. The acoustic propagation environment was reconstructed from this set in conjunction with bottom parameters extracted by use of acoustic inversion techniques. The resulting space- and time-varying sound speed field was synthesized from an internal wave field composed of both a spatially diffuse (linear) contribution and a spatially localized (nonlinear) component, the latter consisting of solitary waves propagating with the internal tide. Acoustic simulation results at 224 and 400 Hz were obtained from a solution to an elastic parabolic equation and are presented as examples of propagation through this evolving environment. Modal decomposition of the acoustic field received at a vertical line array was used to clarify the effects of both internal wave contributions to the complex structure of the received signals.

Effects of biatrial pacing in prevention of postoperative atrial fibrillation after coronary artery bypass surgery

BACKGROUND

Atrial fibrillation (AF) is common after coronary artery bypass surgery (CABG) and results in prolonged hospitalization. The purpose of this study was to evaluate the efficacy of biatrial pacing in preventing post-CABG AF compared with single-site atrial pacing.

METHODS AND RESULTS

A total of 132 patients who had no history of AF and who underwent CABG were randomized to 1 of the following 4 groups: biatrial pacing (BiA), left atrial pacing (LA), right atrial pacing (RA), or no pacing (control) in postoperative period. Overdrive atrial pacing was performed for 5 days. The incidence of AF was significantly reduced in the BiA group (12.5%) compared with the other 3 groups (LA, 36.4%; RA, 33.3%; control, 41. 9%; P<0.05). The mean length of hospital stay was significantly reduced in the BiA group. At baseline, the mean P-wave duration (P(dur)) and dispersion (P(dis)) were not prolonged. BiA pacing resulted in the most significant percentage of reduction in P(dis) when compared with the LA or RA groups (BiA, 42+/-8%; LA, 13+/-6%; RA, 10+/-9%; P<0.05 for BiA versus LA or RA). No significant differences existed in mean P(dur) and P(dis) between patients who developed AF and those who remained in sinus rhythm at baseline. However, only those patients who remained in sinus rhythm had a significant reduction in mean P(dur) and P(dis) after pacing therapy.

CONCLUSIONS

Biatrial overdrive pacing is more effective in preventing post-CABG AF than single-site atrial pacing; this therapy also results in a shortened hospital stay. The overall reduction in atrial activation time with BiA pacing was reflected in the reduction in P(dis).

Single-molecule fluorescence observed with mercury lamp illumination

We demonstrate that it is possible to observe single fluorescent molecules using a standard fluorescence microscope with mercury lamp excitation and an inexpensive cooled charge-coupled device (CCD) camera. With this equipment, we have been able to observe single molecules of tetramethyl-rhodamine, rhodamine 6G, fluorescein isothiocyanate and green fluorescent protein. Immobilized molecules were observed both in air and in aqueous solution.

Left ventricular rupture after mitral valve replacement

BACKGROUND

What are the immediate and long term outcomes of patients who had rupture of the left ventricle after mitral valve replacement?

METHODS

EXPERIMENTAL DESIGN

A retrospective study with a 20-year follow-up.

SETTING

Experience in a single tertiary referral cardiothoracic surgery hospital.

PARTICIPANTS

20 out of 3105 patients that received mitral valve replacement.

INTERVENTION

All these 20 patients received re-exploration for a trial of repair of left ventricular rupture either by an internal or an external or a combined repair.

MEASURES

Operative mortality and long term outcome of the survivals.

RESULTS

Most patients (16.80%) were female and had rheumatic mitral valve disease. The mean age of the patients was 58.1 years. All patients underwent attempted repair, usually by removal of the prosthesis and reconstitution of the ventricle from within the left atrium (75%). Thirteen (65%) patients died. Two late deaths were of unrelated cause. One surviving patient developed a late ventricular false aneurysm but did not undergo repeat surgery. One patient developed severe mitral regurgitation due to tissue failure of the bioprosthesis 12 years after surgery and she underwent a successful reoperation.

CONCLUSIONS

We believe that all patients should be placed back on cardiopulmonary bypass for an internal repair. The long term outcome of the survivals is satisfactory.

Surgical resection of pulmonary metastases

BACKGROUND

To review the results of complete surgical resection of pulmonary metastasis -- a ten-year experience.

SETTING

Retrospective analysis of all patients with lung secondaries who received complete surgical resection of pulmonary metastases (from 1984 to 1995) in Grantham Hospital, Hong Kong. Sixty patients over a 10-year period were studied.

METHODS

Eighty thoracotomies were performed with 88 tumour nodules excised. The follow-up period ranged from 5 months to 111 months.

RESULTS

Thirteen (14.8%) specimens were found to have tumour size greater than 5.0 cm. This may reflect late detection of metastatic tumour and probably accounts for the higher percentage of our patients receiving more major lung resections (63.3%) than just wedge resections (36.6%). The mean survival period for the subgroup with hepatocellular carcinoma was 28.2 months and for the nasopharyngeal carcinoma group was 25 months. The mean survival of the whole group was 26.4 months.

CONCLUSIONS

The favourable outcome for hepatocellular carcinoma and nasopharyngeal carcinoma could be due to the result of selection of patients with more favourable prognosis for surgery. The latent period, using 12 months as a break-off point, did not affect patient survival in our study.

Mediastinal irradiation for graft-versus-host disease in a heart-lung transplant recipient

Graft-versus-host disease in solid organ transplantation is very rare, but the prognosis is poor when the condition causes pancytopenia. We report a case of graft-versus-host disease in a heart-lung transplant recipient who at 2 weeks after transplantation had development of features of graft-versus-host disease, including bone marrow aplasia, that could not be attributed to drugs or viral infections. The diagnosis was confirmed by skin biopsy and demonstration of chimerism of peripheral lymphocytes. Augmentation of immunosuppression with intravenous methylprednisolone resulted in improvement in liver function but had no effect on the pancytopenia. Mediastinal irradiation was given with increase in both white blood cell and platelet counts. Unfortunately the patient eventually died of gastrointestinal bleeding and fungemia.

Surgical resection of pulmonary metastases from nasopharyngeal carcinoma

BACKGROUND

Nasopharyngeal carcinoma (NPC), unlike other head and neck cancers,is known for its propensity for distant metastases. Chemotherapy remains the mainstay of treatment because of this and the chemosensitivity of the tumour, but long-term control is rare. The surgical management of pulmonary metastases of other extrathoracic malignancies prompted this review of surgical management of patients with NPC.

METHODS

Thirteen thoracotomies were performed in 12 patients with pulmonary metastases as the first and only site of relapse of nasopharyngeal carcinoma. Postoperative chemotherapy was given in four patients, radiotherapy to the mediastinum in one patient and both chemotherapy and radiotherapy in two patients. The survival pattern of this group of 12 patients was compared with a historical control group consisting of 65 patients without surgical resection.

RESULTS

Lymph node involvement was documented in four patients during operation. Four patients relapsed after surgical resection, two of them were from the group of three patients with lymph node involvement. The site of subsequent relapse was the lung for three patients and the skeletal system for the fourth. The 2 year actuarial survival of the surgically resected group compared favourably with the historical control group (80% and 24.1%, respectively; P=0.0002 by Mantel-Cox text).

CONCLUSIONS

Surgical resection of pulmonary metastases from NPC seems to be a promising approach thought the effect of case selection cannot be excluded and further studies are indicated. The importance of exploration and dissection of mediastinal nodes in the surgical management of pulmonary metastases from NPC was demonstrated.

Chemical transformation/derivatization of O6-methyl- and O6-(hydroxyethyl)guanine for detection by GC-EC/MS

In this project we set out to make an important class of DNA adducts, comprising O6-alkyl and O6-(hydroxyalkyl)guanines, susceptible to sensitive detection by GC-EC/MS. While existing literature indicated that pentafluorobenzylation would be useful for the ring NH site on these compounds, how to best overcome the polarity of the exocyclic NH2 and OH groups, without losing the O6-alkyl moiety, was less clear. Working with O6-methylguanine and O6-(2'-hydroxyethyl)guanine as representative analytes, we found that the NH2 group could be converted into fluoro without loss of the O6 substituent. For the OH group, a comparison of several derivatives (OR') led to R' = tert-butyl as the best choice at this stage. The latter work, especially via NMR, also allowed exact structural assignments to be made for the N7 and N9 pentafluorobenzyl isomeric derivatives that formed. Of these R' derivatives, the N7 isomers migrated slower on silica-TLC, had higher GC retention times, had lower responses by GC-EC/MS, and were preferentially destroyed as the GC column aged. However, the N9 isomer was slower on TLC when the OH was not derivatized. This behavior was rationalized using a concept of "polar footprint" for the derivatives. The concept also seemed to explain the puzzling GC-EC/MS behavior of some related compounds in our laboratory. Apparently the polar footprint should be minimized in designing derivatives for trace detection by GC-EC/MS.

Inhibition of mammalian ribonucleotide reductase by cis-diamminedichloroplatinum(II)

Ribonucleotide reductase is a highly regulated, rate-limiting activity in the synthesis of DNA. A previous study has shown that the Escherichia coli enzyme is inhibited by the clinically important antitumor agent cis-diamminedichloroplatinum(II) (DDP), and this has led to the hypothesis that ribonucleotide reductase is an important site of action for this chemotherapeutic agent. This hypothesis has been directly tested in this investigation. We observed that DDP inhibits the mammalian ribonucleotide reductase, with 50% inhibition occurring at 0.3 mM. Unlike the E. coli enzyme where only one of the two protein components is targeted by DDP, we observed that both of the mammalian proteins (R1 and R2) were sites for the inhibitory activity of the drug. Colony-forming experiments, enzyme activity studies, and analyses of R1 and R2 message levels in mutant cell lines containing either high levels of ribonucleotide reductase activity or exhibiting resistance to the cytotoxic effects of DDP were used to further investigate the potential role of ribonucleotide reductase in DDP cytotoxic action and drug resistance. These studies did not support a hypothesis formulated in the earlier investigation that inhibition of ribonucleotide reductase is an important component of DDP cytotoxic activity or that it is a major participant in DDP resistance mechanisms. From a biological point of view, DDP is a very active drug, and in addition to its cytotoxic effects it is capable of inducing a variety of cellular changes. Whether or not the inhibition of mammalian ribonucleotide reductase activity that we have described in this study plays a role in mediating any of these other effects remains to be determined.

The facial soft tissue profile of the southern Chinese: prosthodontic considerations

A simple photographic setup was established to produce standardized life-sized black and white prints of Southern Chinese adults. Facial soft tissue profile analysis was performed on 28 men and 31 women aged 19 to 30, dentate Chinese, having class I occlusion and originating from Guangdong province. The facial profile values studied included the profile convexity, the interlabial contour, the nasolabial contour, the columella and upper lip inclination angles to the true horizontal, and the relative positions of upper and lower lips from the Esthetic plane. Data obtained were compared with those from previous Caucasian studies and other accepted empirical values. The lower third of the face presented the greatest ethnic difference: the interlabial contour was more convex and the upper and lower lips were more protrusive among the Southern Chinese. The widely-used standard of a right-angled nasolabial contour proved to be applicable among the Southern Chinese adult males. However, a more obtuse nasolabial angle, almost 100 degrees, occurred among the women.

Reproducibility of natural head position

The orientation of the head, when the natural head position was adopted, was measured relative to the true vertical on standardized black and white profile photographs. Two methods of obtaining the natural head position were compared and their reproducibility tested. No statistically significant difference was found between the two different methods or at different sittings.

Experience with the management of primary endodermal sinus tumor of the mediastinum

Ten male patients with extensive primary endodermal sinus tumor of the mediastinum were treated with chemotherapy (with or without surgical excision and radiation therapy) between 1977 and 1985. Three patients, treated with cyclophosphamide-vincristine-based chemotherapy, died 1.5, 2.5, and 6.0 months, respectively, after initial diagnosis. Of the seven patients treated with cisplatin-based chemotherapy, one patient died of septicemia at 2.5 months after diagnosis and was disease-free at autopsy examination. Three other patients died of progressive disease at 7.0, 13.0, and 14.0 months, respectively. The three survivors remain alive at 17.0, 31.0, and 40.0 months from diagnosis; all are without evidence of disease. Of the three patients who underwent excision of the residual mediastinal tumor after cisplatin-based chemotherapy, persistent local disease was found in two patients. One of these two patients died of recurrent disease. All surviving patients had surgical resection of the tumor either before or after cisplatin-based chemotherapy, with or without radiotherapy and the timing of therapeutic interventions was guided by changes in the serum alpha-fetoprotein concentrations after initial therapy and during follow-up. Our experience suggests that the optimal management of patients with primary mediastinal endodermal sinus tumor requires an aggressive multidisciplinary approach guided by the extent of the tumor and the serum tumor marker levels.

Left subclavian arterioesophageal fistula induced by a foreign body

A left subclavian arterioesophageal fistula was diagnosed in a 35-year-old man at exploratory thoracotomy for suspected aortoesophageal fistula. After successful closure of the arterial fistula the patient developed a mediastinal abscess and esophagopleural fistula. The latter was successfully managed by retrosternal jejunal esophagoplasty followed by excision of the thoracic esophagus. This report documents a case of left subclavian arterioesophageal fistula and illustrates the importance of early diagnosis and surgical intervention of arterial perforation secondary to a foreign body in the esophagus.

An unusual lethal complication of preservation of chordae tendineae in mitral valve replacement

In two patients, several chordae tendineae of the mural leaflet were preserved during mitral valve replacement. Hemorrhagic necrosis and spontaneous rupture of the preserved posterior papillary muscle led to disc entrapment and the death of both patients.

Characteristics of a bacteriophage T4-induced complex synthesizing deoxyribonucleotides

A preparation of bacteriophage T4-induced deoxyribonucleotide synthetase complex is described. This very large complex of enzymes can be separated by centrifugation at 100,000 X g, by sucrose step gradient centrifugation, or with molecular exclusion columns. By direct assay and by unidimensional and two-dimensional acrylamide electrophoretic separations the following T4-coded enzymes were shown to be associated with the complex: ribonucleoside diphosphate reductase, dCMP deaminase, dCTP/dUTPase, dCMP hydroxymethylase, dTMP synthetase, and DNA polymerase. Other phage-coded prereplicative proteins related to DNA replication and other phage functions such as the proteins coded by genes 32, 46, rIIA, and rIIB as well as many unidentified proteins were also consistently associated with the isolated fractions. T4 DNA topoisomerase, a membrane-bound enzyme, was found in quantity in all purified fractions of the complex, even in preparations apparently free of membrane and of T4 DNA. The functional integrity of a segment of the complex was followed by measuring the conversion of [5-3H]CDP to the level of 5-hydroxymethyl dCMP. This series of reactions requires the actions of T4-coded ribonucleoside diphosphate reductase and its associated reducing system, dCTP/dUTPase and dCMP hydroxymethylase, 3H being lost to water at the last step. In this reaction sequence an intermediate, [5-3H]dCMP, is maintained at low steady state concentrations, and argument is presented that the synthesis of deoxyribonucleotides is channeled and normally tightly coupled to DNA replication. One of the primary characteristics of this complex is its ready dissociation of dilution into smaller complexes of proteins and to the free forms of the proteins. That the complex is held together by weak electrostatic forces was supported by its sensitivity to dissociation at moderate salt concentrations. Not only the enzymes required in deoxyribonucleotide synthesis but T4 DNA polymerase, T4 DNA topoisomerase, and a number of other proteins dissociate to varying degrees from the larger complexes under these conditions.

Resistance of red blood cell membrane to oxygen uptake

The apparent association velocity constant (k'c) was determined before and after disruption of the red blood cell membrane in one of several ways: 1) radiation of the cells using a 137Cs source did not significantly alter k'c (95 +/- 39.3 and 118 +/- 35.5 mM-1.s-1), 2) incubation of the cells with sialidase produced no change in k'c (112 +/- 42.6 and 123 +/- 46.8 mM-1.s-1), 3) using papain for the incubation similarly produced no significant alteration in k'c (94 +/- 21.2 and 113 +/- 51.8 mM-1.s-1), 4) a radiomimetic agent p-chloromercuribenzene sulfonate likewise produced no significant alteration in k'c (128 +/- 16.3 and 122 +/- 3.5 mM-1.s-1), and 5) employing phospholipase C to disrupt the membrane k'c did not significantly change (115 +/- 15.3 and 112 +/- 8.7 mM-1.s-1). We conclude that either O2 traverses the membrane in a manner uninfluenced by the manipulations here employed, or that the membrane offers no significant resistance to the speed of O2 uptake.

Replicative bacteriophage DNA synthesis in plasmolyzed T4-infected cells: evidence for two independent pathways to DNA

Bacteriophage T4-infected Escherichia coli rendered permeable to nucleotides by sucrose plasmolysis exhibited two apparently separate pathways or channels to T4 DNA with respect to the utilization of exogenously supplied substrates. By one pathway, individual labeled ribonucleotides, thymidine (tdR), and 5-hydroxymethyl-dCMP could be incorporated into phage DNA. Incorporation of each of these labeled compounds was not dependent upon the addition of the other deoxyribonucleotide precursors, suggesting that a functioning de novo pathway to deoxyribonucleotides was being monitored. The second pathway or reaction required all four deoxyribonucleoside triphosphates or the deoxyribonucleoside monophosphates together with ATP. However, in this reaction, dTTP was not replaced by TdR. The two pathways were also distinguished on the basis of their apparent Mg2+ requirements and responses to N-ethylmaleimide, micrococcal nuclease, and to hydroxyurea, which is a specific inhibitor of ribonucleoside diphosphate reductase. Separate products were synthesized by the two channels, as shown by density-gradient experiments and velocity sedimentation analysis. Each of the pathways required the products of the T4 DNA synthesis genes. Furthermore, DNA synthesis by each pathway appeared to be coupled to the functioning of several of the phage-induced enzymes involved in deoxyribonucleotide biosynthesis. Both systems represent replicative phage DNA synthesis as determined by CsCl density-gradient analysis. Autoradiographic and other studies provided evidence that both pathways occur in the same cell. Further studies were carried out on the direct role of dCMP hydroxymethylase in T4 DNA replication. Temperature-shift experiments in plasmolyzed cells using a temperature-sensitive mutant furnished strong evidence that this gene product is necessary in DNA replication and is not functioning by allowing preinitiation of DNA before plasmolysis.

Simultaneous initiation of synthesis of bacteriophage T4 DNA and of deoxyribonucleotides

In earlier reports we have suggested that bacteriophate T4 DNA replication occurs in a complex composed of the proteins required for polymerization and the system of enzymes synthesizing the deoxyribonucleoside triphosphate precursors of DNA. T4-induced dCMP hydroxymethylase and dTMP synthetase, though demonstrable in extracts soon after infection, are not active in vivo until about 5 min. The in vivo activities increase exponentially for approximately 15 min and then become constant. We have suggested that the exponential period represents the formation of the complexes. This paper shows that the initiation of DNA synthesis and of the two deoxyribonucleotide-synthesizing activities occurs simultaneously and with coinciding exponential kinetics. The in vivo activities of the two enzymes were tested after infection by a number of T4 amber Dna- mutants. Their activities were essentially unchanged compared to the wild-type phage, except on infection by mutants of gene 43 (T4 DNA nucleotidyltransferase or DNA polymerase). With these mutants the rate of increase of dTMP synthetase and dCMP hydroxymethylase activities was always substantially lower than after infection by wild-type phage. It is proposed that an intimate interaction occurs between T4-induced DNA polymerase and the complex of enzymes forming 5-hydroxymethyl-dCMP and dTMP.

Direct participation of dCMP hydroxymethylase in synthesis of bacteriophage T4 DNA

In order to retain in an in situ system the control mechanisms involved in synthesis of bacteriophage T4 DNA, infected cells were made permeable to nucleotides by plasmolysis with concentrated sucrose. Such preparations use exogenous deoxyribonucleotides to synthesize T4 phage DNA. As has been observed with in vivo studies, DNA synthesis was drastically reduced in plasmolyzed preparations from cells infected by amber mutants of genes 1, 32, 41, 42, 43, 44, or 45. Added 5-hydroxymethyl dCTP did not bypass either a mutant of gene 42 (dCMP hydroxymethylase) or of gene 1 (phage-induced deoxyribonucleotide kinase). In a phage system lacking deoxycytidine triphosphatase (gene 56) and the gene-46 product, and therefore incorporating dCTP into DNA, dCTP incorporation did not require dCMP hydroxymethylase, in keeping with in vivo results. With a triple amber mutant of genes 1, 46, and 56 only slight incorporation of dCTP occurred. By contrast, in experiments performed in vivo the synthesis of cytosine-containing DNA was unaffected by an amber mutation in gene 1. These studies provide evidence that dCMP hydroxymethylase, in addition to its known catalytic function, has a second, more direct, role in phage T4 DNA synthesis, apparently in recognition of hydroxymethyl dCTP. The role of the phage-induced deoxyribonucleotide kinase in T4 DNA synthesis in the plasmolyzed system remains unresolved.

Intragenic complementation between temperature-sensitive mutants of gene 42 (dCMP hydroxymethylase) of bacteriophage T4

Interallelic complementation between certain temperature-sensitive mutants of gene 42 of bacteriophage T4 was demonstrated by measuring the incorporation of labeled thymine into DNA.

Mutagenic effect of temperature-sensitive mutants of gene 42 (dCMP hydroxymethylase) of bacteriophage T4

Certain temperature-sensitive mutants of gene 42 of bacteriophage T4 increase the reversion rates of some rII mutants in the same genome by about 4 to 10 times. This effect was usually found at 34 C, an intermediate permissive temperature, but not at 28 C.