The impact of time to adjuvant chemotherapy (AC) on survival in colorectal cancer (CRC): A systematic review and meta-analysis

364

Background: The optimal timing from CRC surgery to initiation of AC is unknown. We report a systematic review and meta-analysis to determine the relationship between time to adjuvant chemotherapy (TTAC) and survival.

Methods: A systematic review of literature was done to identify studies that described the relationship between TTAC and survival. Studies were only included if the distribution of relevant prognostic factors was adequately described, and either comparative groups were balanced or results adjusted for the prognostic factors. Hazard ratio (HR) and TTAC for overall survival (OS) and disease free survival (DFS) from each study were converted to a regression coefficient (β) and standard error (SE) corresponding to a continuous representation per 4 weeks of TTAC. The adjusted β from individual studies were combined using a fixed-effect model. Inverse-variance (1/SE2) was used to weight individual studies. The possible effect of publication bias was investigated using the trim and fill approach.

Results: We identified 9 eligible studies involving 14,357 patients (4 published articles, 5 abstracts). Two studies were randomized trials and 7 were cohort studies. Six studies reported TTAC as a binary variable and 3 reported TTAC as ≥3 categories. An estimate of HR for OS was derived from all 9 studies and estimate for DFS was derived from 5 studies. Meta-analysis demonstrated that a 4-week increase in TTAC was associated with a significant decrease in both OS (HR = 1.12, 95% CI 1.09-1.15), and DFS (HR = 1.15, 95% CI 1.11-1.20). The analysis showed no significant heterogeneity among studies. These TTAC associations remained significant after analysis for potential publication bias, and when the analysis was repeated excluding the two studies of largest weight.

Conclusions: This study demonstrates a 12% increase in the risk of death for each 4 week of delay in the start of AC for CRC. These findings indicate the need for clinicians and health systems managers to take the steps necessary to keep TTAC as short as reasonably achievable. In addition, our results suggest there may be some benefit to AC after a 3-month TTAC delay.

No significant financial relationships to disclose.

Overexpression of α-2,6 sialyltransferase stimulates propagation of human influenza viruses in Vero cells

Human influenza viruses are major concern as the leading cause of global pandemics. In infecting cells, they preferentially bind to sialyloligosaccharides containing terminal N-acetyl sialic acid linked to galactose by an α-2,6-linkage (NeuAcα2,6Gal). The amount of NeuAcα2,6Gal in Vero cells, which are predominantly used for production of influenza vaccines over the past 30 years, may not be as high as that in epithelial cells of human respiratory tract, what leads to the suboptimal virus growth in Vero cells. In this study, we stably transfected Vero cells with cDNA of human α-2,6-sialyltransferase (SIAT1), an enzyme catalyzing α-2,6-sialylation of galactose on glycoproteins. Overexpression of SIAT1 in the transfected Vero cells (Vero-SIAT1 cells) was confirmed by Western blot analysis and immunofluorescence microscopy. Vero-SIAT1 cells expressed 7 times higher amounts of NeuAcα2,6Gal, but 3 times lower amounts of NeuAcα2,3Gal as compared to parental Vero cells. Furthermore, the influenza viruses A (H1N1 and H3N2) and B grew in Vero-SIAT1 cells to the higher titers than in Vero cells. Taken together, these results imply that Vero-SIAT1 cells are useful not only for the propagation of human influenza viruses, but also for the preparation of influenza vaccines.

Microcalorimetric assay on the antimicrobial property of five hydroxyanthraquinone derivatives in rhubarb (Rheum palmatum L.) to Bifidobacterium adolescentis

It was found that the intestinal bacteria balance would be deteriorated by rhubarb especially in long term treatment. Bifidobacteria is one of the most common species of probiotics in human intestine. The suppression of this particular probiotic, such as Bifidobacterium adolescentis, one of the dominant anaerobes in the intestines of humans, might lead to imbalance of intestinal flora and is considered to be potentially riskful for human health. Hence, the inhibitory effects of the five main components of hydroxyanthraquinones (HAQs) contained in rhubarb on B. adolescentis growth were investigated by microcalorimetry to discover the suppression potential of rhubarb and the structure-function relationship of such HAQs. The value of the maximum power- output (P(max)) and slope (k) of the thermogenic growth curves of B. adolescentis were found of decrease in the presence of the five HAQs, while the peak time (T(p)) of the thermogenic curves were found to be delayed. The sequence of antimicrobial activity of the five HAQs is rhein>emodin>aloe-emodin>chrysophanol>physicion. The functional groups carboxyl, hydroxyl and hydroxylmethyl on phenyl ring in HAQs could improve the antimicrobial activity. The influence of substituent groups on anti- B. adolescentis activity might be related with the polarity and the sequence was carboxyl>hydroxyl>hydroxylmethyl>methyl and methoxyl.

A gene-based avian influenza vaccine in poultry

Highly pathogenic avian influenza A (HPAI) viruses, specifically H5N1 strains, cause widespread morbidity and mortality in domestic and wild bird populations, and recent outbreaks have resulted in severe economic losses. Although still largely confined to birds, more than 300 human cases resulting in deaths have been reported to the World Health Organization. These sporadic human cases result from direct transmission from infected birds; however, a sustained outbreak of HPAI H5N1 increases the potential for the emergence of a human pandemic strain. One approach to the containment of HPAI H5N1 is the development of vaccines for use in poultry. Currently, the majority of avian influenza vaccines for poultry are traditional whole-virus vaccines produced in eggs. Although highly efficacious, these vaccines are hindered by long production times, inflexibility in quickly altering antigenic composition, and limited breadth of protection. Newer vaccines with more efficient manufacturing processes, enhanced efficacy, and cross-protection against multiple strains would improve preparedness. Reverse genetics technology has provided one such method, and emerging gene-based vaccines offer another approach that reduces dependence on egg-based production and human exposure to pathogenic viruses. Gene-based vaccines also provide rapid manufacturing, enhanced precision and versatility, and the capacity to protect against a broad range of viral subtypes. Vectors for these vaccines include replication-defective viruses, bacterial vectors, and DNA. Here we review the features of gene-based vaccination that may facilitate the control of HPAI H5N1 in poultry, and highlight the development of a hemagglutinin-based multivalent DNA vaccine that confers protection in mice and chickens.

Magnetic field dependent critical current density of Bi–Sr–Ca–Cu–O superconductor in bulk and tape form with addition of Fe3O4 magnetic nanoparticles

The (Bi,Pb)2Sr2Ca2Cu3O10-(Fe3O4)x superconductor for x=0, 0.01, 0.03, and 0.05 were prepared. The average size of Fe3O4 used was 40 nm. The maximum critical current density (Jc) in the bulk form was observed in the x=0.01 sample. Based on this result, Ag sheathed high temperature superconductor tapes with starting compositions (Bi,Pb)2Sr2Ca2Cu3O10-(Fe3O4)0.01 were fabricated using the powder in tube method. The microstructure, phase formation, critical temperature, and transport critical current density were studied. The Jc of the nanosized Fe3O4 added tapes is 5130 A/cm2 at 77 K and 23130 A/cm2 at 30 K in zero fields. The nonadded tapes showed a lower Jc, 3090 A/cm2 at 77 K and 12 400 A/cm2 at 30 K. A sudden decrease in Jc in low magnetic fields (B<0.10 T) when applied parallel and perpendicular to the tapes surface was observed. By adding magnetic nanoparticles, the full vortex magnetic energy can be used to enhance Jc and thus, magnetic nanoparticles such as Fe3O4 can act as an effective flux pinning center leading to the enhancement of Jc in the bulk as well as the tape form.

163. MATERNAL FOLIC ACID SUPPLEMENTATION INDUCED ALTERATIONS IN METABOLIC HEALTH OF PROGENY: ROLE OF microRNA REGULATORY NETWORKS

Background: Nutrition in early life can influence metabolic functionality in later life, in part via heritable epigenetic changes, which modify gene expression without altering DNA sequence. Folate supplies methyl groups for the methylation of DNA and histones, both major epigenetic marks that change dynamically in utero. We have recently shown that maternal folic acid supplementation (MFAS) in the pregnant rat increases insulin sensitivity in adult male progeny, while decreasing that of females. The molecular basis of this is unknown but microRNAs may play a role. MicroRNAs are epigenetically regulated non-coding RNAs that downregulate post-transcriptional expression of their targets. MFAS may modulate epigenetics and expression of microRNAs and their targets in adult progeny to alter insulin sensitivity. Aims/Hypotheses: The effect of MFAS before and throughout pregnancy on microRNA expression in liver and skeletal muscle of adult progeny was determined. Methods: Female Wistar rats were fed Control (n=11) or Folic Acid Supplemented (n=9) diets containing either 2 or 6 mg folic acid/kg respectively, from two weeks before mating and throughout pregnancy. One male and female progeny per litter were sacrificed on postnatal day 90 and microRNA expression was determined by Exiqon microRNA microarray v.8.1. Results: MFAS altered hepatic microRNA expression in adult male progeny, but did not alter that in females. Sixteen hepatic microRNAs were differentially expressed, with five predicted in silico (rno-miR: 23a, 23b, 212, 298 and 325-5p) to target several key insulin signalling molecules (p85α, p110β, Akt2, and Prkcz). miR-122a, which promotes cholesterol and lipid synthesis in vivo, was also downregulated. MFAS did not alter microRNA expression in skeletal muscle of adult male or female progeny. Conclusions: MFAS alters hepatic microRNA expression in adult male progeny. Changes in their expression together with their targets in insulin signalling pathway may initiate increased insulin sensitivity in adult male progeny.

160. THE POTENTIAL ROLE OF microRNAs IN THE DEVELOPMENT OF THE HUMAN PLACENTA IN EARLY PREGNANCY

Placental functional development is characterised by dynamic and co-ordinated changes in expression of genes that drive invasion, differentiation and growth. These changes may arise in part from altered expression of microRNAs (miRNAs) via their regulatory networks. MiRNAs are short, single-stranded, non-coding RNAs involved in the post-transcriptional repression of gene expression. MiRNAs bind to complementary sites in the 3'UTR of target mRNAs to repress or silence translation. MiRNAs have been detected in the mammalian placenta, but their patterns of expression throughout pregnancy have not been systematically characterized. Using microarrays, miRNA gene expression was compared at two stages (6–8 weeks, 10–12 weeks) in early gestation, in chorionic villi of human placentas (term ~40 weeks). Putative and validated targets of differentially expressed miRNAs were extracted from freely accessible databases, miRBase [1], PicTar [2], TargetScan [3] and miRecords [4]. 15 miRNAs were differentially expressed between these gestational ages (p<0.05). 11 of these miRNAs were upregulated in 10–12 week villi and 4 were downregulated. Many of the differentially expressed miRNAs are members of the same polycistronic clusters, suggesting that these miRNAs may be co-expressed. Shared targets of differentially expressed miRNAs from the same clusters were assessed using Ingenuity Pathways Analysis, to search for significantly represented molecular networks. All downregulated miRNAs at 10–12 weeks shared 35 putative targets and fell into 1 of 2 clusters, on chromosome 13 or X. Previously validated targets include PTEN [5], Notch1 [6], VEGFA [7], CDKN2A [8] and DHFR [9] . Six of the upregulated miRNAs at 10–12 weeks are members of 3 clusters on chromosome 19, 9 and X. Networks targeted by these cluster members include PTEN, HIF1α and IL-12 signalling. Together all of these processes are active and important in early placentation and their predicted targeting by differentially expressed miRNAs is consistent with an important role in placental development.

Waiting times for cancer surgery in Ontario: 1984-2000

AIMS

Despite persistent public interest and the perception among clinicians and patients that increased waiting time for cancer surgery is related to worse outcomes, little is known about waiting time for cancer surgery. Our aim is to describe changes in waiting times for cancer surgery in Ontario between 1984 and 2000, and associated factors.

MATERIALS AND METHODS

The interval between date of diagnosis and admission for surgery for all patients receiving surgical treatment for cancers of the larynx, hypopharynx, stomach, colon, rectum, breast, cervix, uterus, prostate, bladder, lung and oesophagus was calculated for all patients in Ontario between 1984 and June 2000. This was accomplished by retrospective review of prospectively gathered electronic records.

RESULTS

Median waiting times for cancer surgery increased for all cancer types, including substantial increases for oesophageal cancer (from 14 days between 1984 and 1987 to 33 days between 1998 and 2000), breast cancer (12-27 days), and laryngeal cancer (16-33 days). A similar increase in waiting times for patients awaiting radiation therapy was identified. The proportion of patients receiving diagnosis and definitive resection on the same admission for colon cancer decreased (from 79.4% between 1984 and 1987 to 47.9% between 1998 and 2000) for laryngeal cancer (35.5-9.4%), and for lung cancer (61.6-23.0%). Age, sex, cancer site, hospital type, household income and cancer centre location were all independently related to waiting times.

CONCLUSIONS

Waiting times for cancer surgery increased substantially between 1984 and 2000. Waiting times were influenced by disease, patient and health-system-related factors.

Mechanism of alpha-adrenergic regulation of expressed hKv4.3 currents

The transient outward potassium current (I(to)) is an important repolarizing current in the mammalian heart. I(to) is regulated by adrenergic stimulation; however, the effect of agonists on this current, and consequently the action potential duration and profile, is variable. An important source of the variability is the difference in the channel genes that underlie I(to). There are two subfamilies of candidate genes that are likely to encode I(to) in the mammalian heart: Kv4 and Kv1.4; the predominance of either gene is a function of the species, stage of development, and region of the heart. The existence of different isoforms of the Kv4 family (principally Kv4.2 or Kv4.3) further complicates the effect of alpha-adrenergic modulation of cardiac I(to). In the human ventricle, hKv4.3 is the predominant gene underlying I(to). Two splice variants of human Kv4.3 (hKv4.3) are present in the human ventricle; the longer splice variant contains a 19-amino acid insert in the COOH-terminus with a consensus protein kinase C (PKC) site. We used heterologous expression of hKv4.3 splice variants and studies of human ventricular myocytes to demonstrate that alpha-adrenergic modulation of I(to) occurs through a PKC signaling pathway and that only the long splice variant (hKv4.3-L) is modulated via this pathway. Only a single hKv4.3-L monomer in the tetrameric I(to) channel is required to confer sensitivity to phenylephrine (PE). Mutation of the PKC site in hKv4.3-L eliminates alpha-adrenergic modulation of the hKv4.3-encoded current. The similar, albeit less robust, modulation of human ventricular I(to) by PE suggests that hKv4.3-L is expressed in a functional form in the human heart.

[Measurement of distortion product otoacoustic emissions in guinea pig]

OBJECTIVE

To establish a stable detecting method of distortion product otoacoustic emissions (DPOAEs).

METHOD

After cutting off tragus, seven healthy pigmented guinea pigs (thirteen ears) were selected to measure the DPOAEs at the frequency of 2f1-f2 (cubic DPOAEs). The I/O function and latency at f2 = 2, 4, 6 kHz were analyzed.

RESULT

The incidence of DPOAEs at all frequencies was 100%. The maximal amplitude of input-output function was (27.24 +/- 4.15) dB SPL, (27.98 +/- 4.05) dB SPL and (41.45 +/- 1.20) dB SPL respectively; latency was (2.06 +/- 0.21) ms, (1.52 +/- 0.16) ms and (1.37 +/- 0.08) ms at the corresponding frequencies.

CONCLUSION

After the improvement of detection, it is satisfactory to measuring DPOAE in animals because of the high incidence, high amplitude and good repetition.

[Chronic hypoxia altered the mRNA expression of cyclooxygenase in intrapulmonary artery smooth muscle cell]

OBJECTIVE

To elucidate the effect of chronic hypoxia on the cyclooxygenase-2 mRNA expression in pulmonary artery smooth muscle cells of rats.

METHODS

The gene expressions of COX-1 and COX-2 during acute hypoxia were measured with semi-quantified RT-PCR in the 2nd, 4th and 6th subculture of intrapulmonary artery smooth muscle cells (PASMC) of wistar rats under normoxic and continuous hypoxic condition separately.

RESULTS

In all three generations, the expressions of COX-1 had no significant changes in hypoxia, while the COX-2 mRNA expression was higher in chronic hypoxic group than that in normoxic group and elevated with the duration of hypoxia exposure. After exposure to acute hypoxia, the augmentation of COX-2 mRNA expression in PASMC was higher in chronic hypoxic group than in normoxic group in all three subcultures.

CONCLUSION

Chronic hypoxia could enhance the mRNA expression of cyclooxygenase-2 caused by acute hypoxia in PASMC of rats. It might be responsible for the lower HPV under chronic hypoxia.

Effects of extrinsic positive end-expiratory pressure on cardiopulmonary function in patients with chronic obstructive pulmonary disease

OBJECTIVE

To choose one optimal extrinsic positive end-expiratory pressure (PEEPe) for ventilated patients with chronic obstructive pulmonary disease (COPD) and to compare two methods for choosing the optimal level of PEEPe.

METHODS

Ten ventilated patients with COPD were included in the study. First, static intrinsic positive end-expiratory pressure (PEEPi, st) was measured when PEEPe was zero, and the PEEPi, st was called PEEPi, stz. PEEPe at 0%, 40%, 50%, 60%, 70%, 80%, 90% and 100% of PEEPi, stz, respectively, were applied randomly. Respiratory mechanics, hemodynamics, and oxygen dynamics were recorded 30 minutes after the level of PEEPe was changed.

RESULTS

When PEEPe was not higher than 80% of PEEPi, stz, no measurement changed significantly. When PEEPe was increased to 90% and 100% of PEEPi, stz, PEEPi, st, peak inspiratory pressure, plateau pressure, pulmonary capillary wedge pressure and central venous pressure increased significantly, P < 0.01. Cardiac output and left ventricular work index decreased significantly, P < 0.01. Oxygen delivery decreased significantly, P < 0.05. When PEEPe was increased to 100% of PEEPi, stz, the right ventricular work index decreased significantly, P < 0.05.

CONCLUSION

Eighty percent of PEEPi, stz was the upper limit of PEEPe. The results of the two methods used to set the level of PEEPe were identical.

Effects of extrinsic positive end-expiratory pressure on work of breathing in patients with chronic obstructive pulmonary disease

OBJECTIVE

To investigate the effects of extrinsic positive end-expiratory pressure (PEEPe) on work of breathing in patients with chronic obstructive pulmonary disease (COPD) and their corresponding mechanism.

METHODS

Ten ventilated patients with COPD were included in the study. A Bicore CP-100 pulmonary monitor (Bicore Monitoring System, USA) was used for monitoring respiratory mechanics. First, dynamic intrinsic positive end-expiratory pressure (PEEPi, dyn) was measured when PEEPe was zero, which was called PEEPi, dynz. Then the PEEPe was set randomly at 0%, 40%, 60%, 80% and 100% of PEEPi, dynz respectively. Pulmonary mechanics and other parameters (heart rate, blood pressure and blood gas analysis) were measured 30 minutes after the level of PEEPe was changed.

RESULTS

Work of breathing patient (WOBp), pressure time product, difference of esophageal pressure and PEEPi, dyn decreased significantly when PEEPe was applied, and continued decreasing as PEEPe was increased. Work of breathing ventilator increased significantly when PEEPe was increased to 80% and 100% of PEEPi, dynz. Significantly positive linear correlation was found between the changes in WOBp and in PEEPi, dyn.

CONCLUSIONS

WOBp decreases gradually as PEEPe is increased. WOBp decreases by narrowing the difference between the alveolus pressure and the central airway pressure at the end of expiration when PEEPe is applied.

[Contralateral suppression of latency during distortion product otoacoustic emissions detection in guinea pigs]

OBJECTIVE

To investigate the cochlear micromechanics and the function of cochlear efferent system by detecting the distortion product otoacoustic emissions (DPOAE) with or without contralateral acoustic stimulation.

METHODS

The DPOAE amplitude and latency of the cubic DPOAE (2f1-f2) were measured at f2 = 2, 4 and 6 kHz with or without 70 dB SPL broad-band noise contralateral stimulation in ears of 12 healthy pigmented guinea pigs, which were divided into two groups(A and B) and tested with different primary intensity level combinations. On the next day, an operation was made to open the acoustic bulla of right ear in Group A. Kainic Acid (KA, 1 microL of 60 mmol/L) was applied onto the round window membrane and wiped up carefully after three hours. The amplitude and latency of the cubic DPOAE from the left ear were measured after 6 hours of KA administration, with or without contralateral noise stimulation.

RESULTS

Before the KA treatment, the amplitude of DPOAE induced by primaries of equal levels (L1 = L2) presented no significant change and the latency prolonged significantly during contralateral acoustic stimulation (Group A). But the amplitude at 2, 4 kHz of DPOAE induced by primaries of different levels (L1 > L2) decreased significantly and the latency also prolonged significantly (Group B). After KA administration in the contralateral ear of Group A, the contralateral acoustic stimulation had no significant effect on either amplitude or latency of DPOAE measured ipsilaterally.

CONCLUSION

The result demonstrates that the latency is a sensitive index for the cochlear contralateral suppression. The efferent system may act as a negative feedback during the cochlear transduction.

Development of a three-dimensional transmigration assay for testing cell--polymer interactions for tissue engineering applications

The ability of synthetic or natural scaffolds to support invasion of cells from surrounding tissue is a key parameter for tissue engineering (TE). In this study, the migration of fibroblasts, chondrocytes, and osteoblasts into biodegradable polymer scaffolds was evaluated using a novel, three-dimensional (3-D) transmigration assay. This assay is based on a cell-populated contracted collagen lattice with a biodegradable polymer scaffold implanted at the center of the collagen gel. Cell migration into the scaffolds was assessed both quantitatively and qualitatively following various time lengths in culture using image analysis. Chondrocytes, incorporated within the collagen lattice, migrated into polymer scaffolds, when cultured both statically or in a rotating bioreactor. However, the bioreactor cultures resulted in a significantly greater cell invasion as compared to static cultures. There was a cell density-dependent osteoblast migration from collagen lattice into polymer scaffold, when tested in the transmigration assay. In addition, polymer scaffolds, treated with or without recombinant human platelet-derived growth factor (rh-PDGF-BB) were evaluated for fibroblast migration. The presence of rh-PDGF-BB resulted in significantly greater fibroblast invasion as compared to untreated scaffolds. Our studies suggest that the transmigration model provides a rapid system for testing cell invasion of potential scaffolds for tissue engineering applications.

[The effects of extrinsic positive end-expiratory pressure on work of breathing in patients with chronic obstructive pulmonary disease]

OBJECTIVE

To study the effect of extrinsic positive end-expiratory pressure(PEEPe) on work of breathing in chronic obstructive pulmonary disease (COPD) patients and its mechanism.

METHODS

10 ventilated patients [4 males and 6 females with mean age of (70.1 +/- 5.5) years] with exacerbation of COPD were admitted into the study. All the patients' cardiopulmonary functions were stable, and they could receive pressure support ventilation (PSV). Patients with sever heart dysfunction, hepatic dysfunction, renal dysfunction or fever were ruled out. Each patient had an esophagus balloon pressure sensor inserted, and the esophagus balloon was properly positioned using "occlusion test". Flow sensor was placed at the end of tracheal tube opening. Then esophagus balloon pressure sensor and flow sensor were connected with Bicore CP-100 pulmonary monitor. Dynamic intrinsic positive end-expiratory pressure (PEEPi, dyn), difference of esophagus pressure (dPes), work of breathing patient (WOBp), work of breathing ventilator (WOBv), pressure time product (PTP), tidal volume (Vt), respiratory rate (RR), minute ventilation (MV), peak inspiratory flow rate (PIFR), peak expiratory flow rate (PEFR), expiratory airway resistance (Rawe), fraction of inspiration (Ti/Ttot) and so on were measured. PEEPi,dyn was measured by esophagus balloon technique. Electrocardiogram and noninvasive blood pressure modes were added to HP M1165A monitor. Heart rate (HR) and blood pressure (BP) were also measured. Arterial blood was analyzed to measure pH, partial pressure of oxygen in arterial blood (PaO(2)), partial pressure of carbon dioxide in arterial blood (PaCO(2)) and saturation of arterial blood oxygen (SaO(2)). At first, PEEPi, dyn was measured when PEEPe was zero, which was called PEEPi, dynz and was set as baseline. Then PEEPe was set randomly, which was 0%, 40%, 60%, 80% and 100% of PEEPi, dynz respectively. Other parameters remained stable. All the indexes were measured 30 minutes after the level of PEEPe was changed.

RESULTS

WOBp decreased as PEEPe increased, from (1.08 +/- 0.49) J/L of PEEPe-0% of PEEPi,dynz to (0.57 +/- 0.32) J/L of PEEPe-100% of PEEPi, dynz, and significant difference was found between each level of PEEPe and the baseline (P < 0.01). But we didn't find significant difference between PEEPe-80% of PEEPi,dynz and PEEPe-100% of PEEPi, dynz. WOBv increased significantly as PEEPe increased, from (1.50 +/- 0.47) J/L of PEEPe-0% of PEEPi, dynz to (1.82 +/- 0.56) J/L of PEEPe-80% of PEEPi, dynz and (1.85 +/- 0.48) J/L of PEEPe-100% of PEEPi,dynz(P < 0.01). The total WOB (WOBp + WOBv) remained steady. PTP trended to decrease, from (153.6 +/- 76.8) cm H(2)O x s x m(-1) of PEEPe-0% of PEEPi, dynz to (86.9 +/- 45.9) cm H(2)O x s x m(-1) of PEEPe-100% of PEEPi, dynz; the difference of PTP between PEEPe-40% of PEEPi,dynz and PEEPe-0% of PEEPi, dynz was significant(P < 0.05), the differences between other levels of PEEPe and PEEPe-0% of PEEPi, dynz were very significant (P < 0.01), but no significant difference was found between PEEPe-80% of PEEPi, dynz and PEEPe-100% of PEEPi, dynz. PEEPi,dyn also decreased significantly as PEEPe increased, from (7.70 +/- 1.42) cm H(2)O of PEEPe-0% of PEEPi, dynz to (2.10 +/- 0.57) cm H(2)O of PEEPe-100% of PEEPi, dynz, very significant differences were found between each level of PEEPe and the baseline (P < 0.01). Significant positive linear correlation was found between DeltaWOBp and DeltaPEEPi, dyn were(r = 0.609, P < 0.01, n = 10). dPes decreased as PEEPe increased, from (15.20 +/- 4.16) cm H(2)O of PEEPe-0% of PEEPi, dynz to (8.20 +/- 4.13) cm H(2)O of PEEPe-100% of PEEPi, dynz, and very significant differences were found between each level of PEEPe and the baseline (P < 0.01). But the difference between PEEPe-80% of PEEPi, dynz and PEEPe-100% of PEEPi, dynz wasn't significant, even dPes of PEEPe-100% of PEEPi, dynz was higher than that of PEEPe-80% of PEEPi, dynz. Vt didn't change markedly. RR, MV and f/Vt increased slightly. Both PIFR and PEFR didn't change markedly. At the same time, HR, BP and blood gas analysis were investigated, but no significant change was found.

CONCLUSION

PEEPe can reduce WOBp significantly and improve the coordination between the patient and ventilator. It is shown that decrement of pressure difference between alveolar and central airway leads to decrement of WOBp.

Preparing transgenic animals with a simplified method of morula aggregation using es cells

The authors describe an ES cell technique that resolves the problems of time, expense, and inconsistency often encountered in the production of transgenic mice via DNA microinjection.

A novel peroxiredoxin of the plant Sedum lineare is a homologue of Escherichia coli bacterioferritin co-migratory protein (Bcp)

We cloned a gene encoding a 17-kDa protein from a cDNA library of the plant Sedum lineare and found that its deduced amino acid sequence showed similarities to those of Escherichia coli bacterioferritin co-migratory protein (Bcp) and its homologues, which comprise a discrete group associated with the peroxiredoxin (Prx) family. Studies of the recombinant 17-kDa protein produced in E. coli cells revealed that it actually had a thioredoxin-dependent peroxidase activity, the hallmark of the Prx family. PrxQ, as we now designate the 17-kDa protein, had two cysteine residues (Cys-44 and Cys-49) well conserved among proteins of the Bcp group. These two cysteines were demonstrated to be essential for the thioredoxin-dependent peroxidase activity by analysis of mutant proteins, suggesting that these residues are involved in the formation of an intramolecular disulphide bond as an intermediate in the reaction cycle. Expression of PrxQ suppressed the hypersensitivity of an E. coli bcp mutant to peroxides, indicating that it might exert an antioxidant activity in vivo.

Human lactoferrin binds and removes the hemoglobin receptor protein of the periodontopathogen Porphyromonas gingivalis

Porphyromonas gingivalis possesses a hemoglobin receptor (HbR) protein on the cell surface as one of the major components of the hemoglobin utilization system in this periodontopathogenic bacterium. HbR is intragenically encoded by the genes of an arginine-specific cysteine proteinase (rgpA), lysine-specific cysteine proteinase (kgp), and a hemagglutinin (hagA). Here, we have demonstrated that human lactoferrin as well as hemoglobin have the abilities to bind purified HbR and the cell surface of P. gingivalis through HbR. The interaction of lactoferrin with HbR led to the release of HbR from the cell surface of P. gingivalis. This lactoferrin-mediated HbR release was inhibited by the cysteine proteinase inhibitors effective to the cysteine proteinases of P. gingivalis. P. gingivalis could not utilize lactoferrin for its growth as an iron source and, in contrast, lactoferrin inhibited the growth of the bacterium in a rich medium containing hemoglobin as the sole iron source. Lactoferricin B, a 25-amino acid-long peptide located at the N-lobe of bovine lactoferrin, caused the same effects on P. gingivalis cells as human lactoferrin, indicating that the effects of lactoferrin might be attributable to the lactoferricin region. These results suggest that lactoferrin has a bacteriostatic action on P. gingivalis by binding HbR, removing it from the cell surface, and consequently disrupting the iron uptake system from hemoglobin.

PRL-1 PTPase expression is developmentally regulated with tissue-specific patterns in epithelial tissues

The mechanisms controlling tyrosine phosphorylation of cellular proteins are important in the regulation of many cellular processes, including development and differentiation. Protein tyrosine phosphatases (PTPases) may be as important as protein tyrosine kinases (PTKs) in these processes. PRL-1 is a distinct PTPase originally identified as an immediate-early gene in liver regeneration whose expression is associated with growth in some tissues but with differentiation in others. We now demonstrate that the PRL-1 protein is expressed during development in a number of digestive epithelial tissues. It is expressed at variable time points in the developing intestine, but its expression is limited to the developing villus enterocytes. In the gastric epithelium, PRL-1 expression in the adult is restricted to zymogen cells. PRL-1 is also expressed in the developing liver and esophagus and in the epithelia of the kidney and lung. In each of these contexts, the expression of PRL-1 is associated with terminal differentiation, suggesting that it may play a role in this important developmental process.

Ratiometry of transmembrane voltage-sensitive fluorescent dye emission in hearts

Transmembrane voltage-sensitive fluorescence measurements are limited by baseline drift that can obscure changes in resting membrane potential and by motion artifacts that can obscure repolarization. Voltage-dependent shift of emission wavelengths may allow reduction of drift and motion artifacts by emission ratiometry. We have tested this for action potentials and potassium-induced changes in resting membrane potential in rabbit hearts stained with di-4-ANEPPS [Pyridinium, 4-(2-(6-(dibutylamino)-2-naphthalenyl) ethenyl)-1-(3-sulfopropyl)-, hydroxide, inner salt] using laser excitation (488 nm) and a two-photomultiplier tube system or spectrofluorometer (resolution of 500-1,000 Hz and <1 mm). Green and red emissions produced upright and inverted action potentials, respectively. Ratios of green emission to red emission followed action potential contours and exhibited larger fractional changes than either emission alone (P < 0.001). The largest changes and signal-to-noise ratio (signal/noise) were obtained with numerator wavelengths of 525-550 nm and denominator wavelengths of 650-700 nm. Ratiometry lessened drift 56-66% (P < 0.015) and indicated decreases in resting membrane potential. Ratiometry lessened motion artifacts and increased magnitudes of deflections representing phase-zero depolarizations relative to total deflections by 123-188% in intact hearts (P < 0.02). Durations of action potentials at different pacing rates, temperatures, and potassium concentrations were independent of whether they were measured ratiometrically or with microelectrodes (P > or = 0.65). The ratiometric calibration slope was 0.017/100 mV and decreased with time. Thus emission ratiometry lessens the effects of motion and drift and indicates resting membrane potential changes and repolarization.

Metabolism of the dorsal cochlear nucleus in rat brain slices

In vitro brain slices of the cochlear nucleus have been used for electrophysiological and pharmacological studies. More information is needed about the extent to which the slice resembles in vivo tissue, since this affects the interpretation of results obtained from slices. In this study, some chemical parameters of the dorsal cochlear nucleus (DCN) in rat brain slices were measured and compared to the in vivo state. The activities of malate dehydrogenase and lactate dehydrogenase were reduced in some DCN layers of incubated slices compared to in vivo brain tissue. The activities of choline acetyltransferase and acetylcholinesterase were increased or unchanged in DCN layers of slices. Adenosine triphosphate (ATP) concentrations for in vivo rat DCN were similar to those of cerebellar cortex. Compared with in vivo values, ATP concentrations were decreased in the DCN of brain slices, especially in the deep layer. Vibratome-cut slices had lower ATP levels than chopper-cut slices. Compared with the in vivo data, there were large losses of aspartate, glutamate, glutamine, gamma-aminobutyrate and taurine from incubated slices. These amino acid changes within the slices correlated with the patterns of release from the slices.

[The role of mtDNA deletion in the sensitivity to aminoglycoside antibiotic induced deafness]

OBJECTIVE

To establish an animal model of mitochondrial DNA (mtDNA) deletion and investigate the possible role of mtDNA deletion in aminoglycoside antibiotic induced deafness.

METHODS

Thirty wistar rats (4 months) were randomly divided into group A and B. Doxorubicin (DOX) was subcutaneously injected at doses of 2 mg/kg twice per week for 3 months in group A and then kanamycin (KM) was intraperitoneally injected 500 mg/kg per day for 10 consecutive days. The treatments of group B were identical to group A, except normal saline was substituted for DOX. The thresholds of auditory brainstem response (ABR) were measured before and after the drug administrations. The inner ear membranous labyrinthine tissue was harvested and mtDNA was amplified to identify 4,834 bp deletion by PCR technique.

RESULTS

The elevation of the mean ABR thresholds in group A(67.08 +/- 8.59) dB peSPL was significantly higher than that in group B (12.71 +/- 4.42) dB peSPL after KM administration (P < 0.001). In group A, 9 of the 15 rats demonstrated 4,834 bp mtDNA deletion. However, mtDNA 4,834 bp deletion was negative in group B animals.

CONCLUSION

DOX can induce mtDNA deletion in the inner ear tissue of the rat. mtDNA deletion in the inner ear may play an important role in the hypersensitivity to aminoglycoside antibiotic ototoxicity.

p53 inhibition by the LANA protein of KSHV protects against cell death

Kaposi's sarcoma-associated herpesvirus (KSHV), or human herpesvirus 8, has been implicated in the development of Kaposi's sarcoma (KS) and several B-cell lymphoproliferative diseases. Most cells in lesions derived from these malignancies are latently infected, and different viral gene products have been identified in association with lytic or latent infection by KSHV. The latency-associated nuclear antigen (LANA), encoded by open reading frame 73 of the KSHV genome, is a highly immunogenic protein that is expressed predominantly during viral latency, in most KS spindle cells and in cell lines established from body-cavity-based lymphomas. Antibodies to LANA can be detected in a high percentage of HIV-infected individuals who subsequently develop KS, although its role in disease pathogenesis is not completely understood. p53 is a potent transcriptional regulator of cell growth whose induction leads either to cell-cycle arrest or apoptosis. Loss of p53 function correlates with cell transformation and oncogenesis, and several viral oncoproteins interact with p53 and modulate its biological activity. Here we show that LANA interacts with the tumour suppressor protein p53 and represses its transcriptional activity. This viral gene product further inhibits the ability of p53 to induce cell death. We propose that LANA contributes to viral persistence and oncogenesis in KS through its ability to promote cell survival by altering p53 function.

Basolateral proteinase-activated receptor (PAR-2) induces chloride secretion in M-1 mouse renal cortical collecting duct cells

1. Using RT-PCR, Northern blot analysis, and immunocytochemistry, we confirmed renal expression of proteinase-activated receptor (PAR-2) and demonstrated its presence in native renal epithelial and in cultured M-1 mouse cortical collecting duct (CCD) cells. 2. We investigated the effects of a PAR-2 activating peptide (AP), corresponding to the tethered ligand that is exposed upon trypsin cleavage, and of trypsin on M-1 cells using patch-clamp, intracellular calcium (fura-2) and transepithelial short-circuit current (ISC) measurements. 3. In single M-1 cells, addition of AP elicited a concentration-dependent transient increase in the whole-cell conductance. Removal of extracellular Na+ had no effect while removal of Cl- prevented the stimulation of outward currents. The intracellular calcium concentration increased significantly upon application of AP while a Ca2+-free pipette solution completely abolished the electrical response to AP. 4. In confluent monolayers of M-1 cells, apical application of AP had no effect on ISC whereas subsequent basolateral application elicited a transient increase in ISC. This increase was not due to a stimulation of electrogenic Na+ absorption since the response was preserved in the presence of amiloride. 5. The ISC response to AP was reduced in the presence of the Cl- channel blocker diphenylamine-2-carboxylic acid on the apical side and abolished in the absence of extracellular Cl-. 6. Trypsin elicited similar responses to those to AP while application of a peptide (RP) with the reverse amino acid sequence of AP had no effect on whole-cell currents or ISC. 7. In conclusion, our data suggest that AP or trypsin stimulates Cl- secretion by Ca2+-activated Cl- channels in M-1 CCD cells by activating basolateral PAR-2.

Stenting of an unprotected left main coronary artery stenosis in a cardiac transplant patient

Cardiac allograft vasculopathy is the leading cause of death in cardiac transplant patients who survive the first year. Retransplantation is limited by shortage of donors and reduced survival rates compared with the initial transplant. Recent reports of successful stenting in these patients may offer some hope, although randomized trials are lacking. Successful stenting of an 'unprotected' left main coronary artery stenosis under cardiopulmonary support is presented in a cardiac transplant patient. A 16-month follow-up angiogram demonstrated a patent stent without restenosis and no interim clinical events.

Proteinase-activated receptor-2 in human skin: tissue distribution and activation of keratinocytes by mast cell tryptase

Proteinase-activated receptor-2 (PAR-2) is a G-protein coupled receptor. Tryptic proteases cleave PAR-2 exposing a tethered ligand (SLIGKV), which binds and activates the receptor. Although PAR-2 is highly expressed by cultured keratinocytes and is an inflammatory mediator, its precise localization in the normal and inflamed human skin is unknown, and the proteases that activate PAR-2 in the skin have not been identified. We localized PAR-2 in human skin by immunohistochemistry, examined PAR-2 expression by RT-PCR and RNA blotting, and investigated PAR-2 activation by mast cell tryptase. PAR-2 was localized to keratinocytes, especially in the granular layer, to endothelial cells, hair follicles, myoepithelial cells of sweat glands, and dermal dendritic-like cells. PAR-2 was also highly expressed in keratinocytes and endothelial cells of inflamed skin. PAR-2 mRNA was detected in normal human skin by RT-PCR, and in cultured human keratinocytes and dermal microvascular endothelial cells by Northern hybridization. Trypsin, tryptase and a peptide corresponding to the tethered ligand (SLIGKVNH2) increased [Ca2+]i in keratinocytes, measured using Fura-2/AM. Although tryptase-containing mast cells were sparsely scattered in the normal dermis, they were numerous in the dermis in atopic dermatitis, and in the dermis, dermal-epidermal border, and occasionally within the lower epidermis in psoriasis. Tryptase may activate PAR-2 on keratinocytes and endothelial cells during inflammation.

[An electrophysiological study of the kainic acid toxicity on cochleas]

OBJECTIVE

The purpose of this study was to investigate the kainic acid (KA) toxicity on cochleas.

METHOD

One microliter KA in the concentration of 60 mM was applied to the round window membrane of guinea pig. The compound action potential (CAP), cochlear microphonic potential (CM) and distortion product otoacoustic emissions (DPOAE) were measured 12 hours after KA was administrated.

RESULT

CAP was suppressed significantly or abolished after the drug administration, however, the CM and DPOAE almost presented no change.

CONCLUSION

The targets of KA toxicity are the primary auditory afferent endings.

[Use PCR technique to detect mitochondrial DNA in rat membranous labyrinth]

OBJECTIVE

To establish a sensitive and reliable method of mtDNA detection in the membranous labyrinth of rat inner ear.

METHOD

A mtDNA segment of 601 bp containing the genes which encode ND1 subunit 16S rRNA in rat inner ear membranous labyrinth was detected by PCR method. The method is compared with Edris's mtDNA isolation method.

RESULT

A 601 bp PCR product of mtDNA in the membranous labyrinth of rat ear inner can be obtained by the two methods. But the requirement of the sample quantities was different for the two methods. The extraction of mtDNA need two of inner ears membranous labyrinth to get reliably result by the method adapted from Seidman. However, the mtDNA extraction procedure from Edris's method need six of inner ears of the in order to get reliably result.

CONCLUSION

The method of mtDNA isolation, amplification and detection membranous labyrinth of rat inner ear by PCR method adapted from seidman is more sersitive.