What is an appropriate caesarean delivery rate for China: a multicentre survey

Objective

To assess the current status of caesarean delivery (CD) in China, propose reference CD rates for China overall, and by regions, investigate the main indications for CDs and identify possible areas for safe reduction.

Design

A multicentre cross‐sectional study.

Setting

A total of 94 hospitals across 23 provinces in China.

Population

A total of 73 977 randomly selected deliveries.

Methods

We used a modified Robson classification to characterise CDs in subgroups and by regions, and the World Health Organization (WHO) C‐Model to calculate reference CD rates.

Main outcome measures

CD rates in China.

Results

In 2015–2016, the overall CD rate in China was 38.9% (95% CI 38.6–39.3%). Considering the obstetric characteristics of the population, the multivariable model‐based reference CD rate was estimated at 28.5% (95% CI 28.3–28.8%). Accordingly, an absolute reduction of 10.4% (or 26.7% relative reduction) may be considered. The CD rate varied substantially by region. Previous CD was the most common indication in all regions, accounting for 38.2% of all CDs, followed by maternal request (9.8%), labour dystocia (8.3%), fetal distress (7.7%) and malpresentation (7.6%). Overall, 12.7% of women had prelabour CDs, contributing to 32.8% of the total CDs.

Conclusions

Nearly 39% of births were delivered by caesarean in China but a reduction of this rate by a quarter may be considered attainable. Repeat CD contributed more than one‐third of the total CDs. Given the large variation in maternal characteristics, region‐specific or even hospital‐specific reference CD rates are needed for precision management of CD.

Tweetable abstract

The caesarean rate in 2015–2016 in China was 38.9%, whereas the reference rate was 28.5%.

The caesarean rate in 2015–2016 in China was 38.9%, whereas the reference rate was 28.5%.

Linked article This article is commented on by M Varner, p. 148 in this issue. To view this mini commentary visit https://doi.org/10.1111/1471-0528.16953.

Development of an Integrated Actuated Hand Orthosis and Virtual Reality System for Home-Based Rehabilitation

Stroke survivors often require a lengthy and costly rehabilitation regimen to regain some of the hand function lost due to stroke. Financial, travel, and scheduling issues can limit access to clinical therapy, thereby depriving individuals of care. Interventions are needed which can extend from the clinic into the home. Home-based rehabilitation strategies, however, must promote sensorimotor learning while maintaining user engagement. Virtual reality, in combination with actuated orthoses, has the potential to provide solutions to these issues. The orthosis can facilitate appropriate therapy while the virtual reality can provide a conduit for maintaining human interaction and engagement in the home environment. In this paper, we describe the development of such an integrated system for hand and upper extremity rehabilitation.

Effects of supplementation with different rapeseed oil sources and levels on production performance, egg quality, and serum parameters in laying hens

This study was to determine the effects of rapeseed oil on production performance, egg quality, and serum parameters in laying hens. A total of 1,080 hens (33-wk-old) were randomly divided into a 1 plus 4 × 2 factorial design including four different rapeseed oil sources [high erucic acid of Mianyang city (MH); high erucic acid of Deyang city (DH); low erucic acid of Mianyang (ML); low erucic acid of Deyang (DL)] at two levels (2% and 4%) for 12 wk. The egg production and egg weight were decreased (P < 0.05) during 9 to 12 wk and 1 to 12 wk, while the average daily feed intake (ADFI) and feed conversion ratio were decreased (P < 0.01) in all phases compared to the control group. Adding ML as oil source had higher (P < 0.05) egg weight compared to DH in all periods in spite of levels. Meanwhile, layers fed 4% rapeseed oil decreased (P < 0.01) egg production compared with 2% in all phases except 1 to 4 wk. Regardless of rapeseed oil sources, hens fed 4% oil decreased (P < 0.05) egg weight in contrast to 2% during the whole experiment except 5 to 8 wk. The ADFI was lower (P < 0.01) in 4% oil inclusion groups compared with 2% during overall phase. Rapeseed oil decreased the yolk color (P < 0.01) and yolk ratio (P = 0.02) and increased (P < 0.01) the albumen height and Haugh unit at 12 wk. Dietary rapeseed oil supplementation resulted in a decreased total triglyceride (TG; P < 0.01) and increased high-density lipoprotein cholesterol (P = 0.02). Regardless of rapeseed oil levels, layers fed MH had higher TG (P < 0.01), TC (P < 0.05), low-density lipoprotein cholesterol (P < 0.05), alanine transaminase (P < 0.01) than those fed other sources. Taken together, the addition of rapeseed oil decreased laying performance, reduced TC and TG in the serum, and increased Haugh unit, with low erucic acid or 2% group showed more pronounced results among all treatments.

[The influence of different thyroid stimulating hormone cut-offs to diagnose subclinical hypothyroidism during the first trimester of pregnancy]

Objective: To analyze the influence of different thyroid stimulating hormone (TSH) cut-offs to diagnose subclinical hypothyroidism (SCH) in the first trimester of gestation. Methods: A total of 896 pregnant women were enrolled in Peking University International Hospital between October 2016 and March 2018. Among them, 421 pregnant women with single fetus who were conformed to the criteria of National Academy of Clinical Biochemistry (NACB), without adverse pregnancy outcomes and obstetric complications, were selected to establish their self-sequential longitudinal reference ranges of thyroid function. Then, SCH was diagnosed in the first trimester, using different TSH cutoffs, such as the upper limit of the first trimester-specific reference range, 4.0 mU/L recommended by the 2017 Guidelines of American Thyroid Association (ATA), 5.17 mU/L (Roche reagent) recommended by 2012 Guidelines of Chinese Society of Endocrinology and Chinese Society of Perinatal Medicine, and 2.5 mU/L recommended by 2011 Guidelines of ATA, respectively. Results: The TSH reference range was 0.12-4.16 mU/L in the first trimester. Using TSH>4.16, 4.0, 5.17 and 2.5 mU/L to diagnose SCH in the first trimester, the prevalence rates were 4.35% (39/896), 5.92% (53/896), 1.56% (14/896) and 20.87% (187/896), respectively. There was no statistically significant difference between the prevalence rates of SCH using the TSH upper reference limit of 4.0 mU/L and 4.16 mU/L (P=0.134). When TSH was defined as>4.0 mU/L to diagnose SCH, the sensitivity, specificity and Youden index was 97.4%, 98.2%, and 0.956, respectively. Conclusions: The TSH upper reference limit of 4.0 mU/L recommended by 2017 Guidelines of ATA can be used as a cut-off to diagnose SCH in first trimester for the areas without trimester-specific reference ranges for TSH in China.

[Effect of ultrasound guided patient-controlled paravertebral block on pulmonary function in patients with multiple fractured ribs]

Objective: To investigated the effects of patient controlled intravenous analgesia and ultrasound guided patient-controlled paravertebral block on pulmonary function in patients with multiple fractured ribs. Methods: From May 2015 to March 2016, 60 patients with multiple rib fractures in Ningbo NO.6 Hospital with American Society of Anesthesiologists Ⅱ-Ⅲ underwent internal fixation, including 30 males and 30 females aged from 16 to 70 years(mean age (54.6±15.2) years). All patients were randomly divided into 2 groups (n=30 each): patient controlled intravenous analgesia(PCIA) group and patient controlled thoracic paravertebral block(PCPB) group.PCIA solution contained sufentanil 2 μg/kg in 100 ml of normal saline.The PCIA pump was set up to deliver a 2 ml bolus dose with 15 minutes lockout interval and background infusion at 2 ml/hour.In PCPB group, the patients received paravertebral injection of 0.2% ropivocaine 15 ml on the corresponding area of fractured side under ultrasound guidance at the end of operation, and then received PCPB.PCPB solution contained 0.75% ropivacaine 67 ml in 250 ml of normal saline, and the pump was set up to deliver a 5 ml bolus dose, with 15 minutes lock out interval and background infusion at 5 ml/hour. Both analgesia lasted to 72 hours after operation.Before the operation, at 30 minutes, 60 minutes, 1 day, 2 days, 3 days after analgesia, arterial blood samples were collected to test the levels of pH, PaO₂, PaCO₂, PaO₂/FiO₂ and PA-aDO₂. The pulmonary function was also examined before and 3 days after the operation through FEV₁ and FEV₁%. Results: Compared with PCIA group at 30 minutes, 60 minutes, 1 day, 2 days, 3 days after analgesia, the level of PaO₂ ((85.1±9.7)mmHg vs.(72.4±12.3)mmHg, (90.3±12.4)mmHg vs.(73.5±7.8)mmHg, (94.2±8.2)mmHg vs.(86.1±5.6)mmHg, (98.5±7.0)mmHg vs. (88.8±7.5)mmHg, (99.6±9.8)mmHg vs. (91.3±8.6)mmHg, P<0.05)) and PaO₂/FiO₂ were significantly increased ((405.1±46.0)mmHg vs. (340.1±58.9)mmHg, (430.5±59.1)mmHg vs. (344.0±65.4)mmHg, (448.3±39.1)mmHg vs. (410.1±26.7)mmHg, (460.1±33.5)mmHg vs. (423.2±36.5)mmHg, (465.1±28.2)mmHg vs. (435.1±40.8)mmHg, P<0.05)), the level of PA-aDO₂ was decreased ((22.9±4.6)mmHg vs. (36.6±5.1)mmHg, (17.7±4.7)mmHg vs. (34.5±2.9)mmHg, (13.8±4.1)mmHg vs. (21.9±3.2)mmHg, (13.5±4.6)mmHg vs. (19.2±3.8)mmHg, (12.4±2.0)mmHg vs. (17.7±2.4)mmHg, P<0.05)), and FEV₁, FEV₁% were significantly increased at 3 days after operation in PCPB group ((2.9±0.4)mmHg vs.(2.2±0.5)mmHg, (78.1±4.7)mmHg vs.(64.8±4.3)mmHg; P<0.01)). Conclusion: Ultrasound guided patient-controlled paravertebral block improves the arterial oxygenation function and accelerates the recovery of pulmonary function in patients with multiple-fractured ribs after internal fixation operation.

[Effects of selenium supplement on atherogenesis of ApoE-knockout mice fed high fat diet]

OBJECTIVE

To investigate the effects of selenium supplement on atherogenesis and endothelial function in ApoE-knockout mice fed high fat diet.

METHODS

ApoE-knockout mice fed with selenium-deficient and high fat diet were randomly allocated into 3 groups based on random number table including control group (not supplied with sodium selenite, n=10), low dosage selenium supplement group (supplied water with 0.1 mg/L sodium selenite, n=10) and high dosage selenium supplement group (supplied water with 0.2 mg/L sodium selenite, n=10). After 15 weeks, the following values were measured: the concentrations of selenium in heart and liver, the levels of serum lipid, the parameters of antioxidant function including activities of superoxide dismutase(SOD) and glutathion peroxidase (GSH-Px) and malondialdehyde (MDA) level in serum, the parameters of endothelial function including serum nitric oxide (NO), endothelin 1(ET-1), and vascular endothelial growth factor (VEGF) levels, and ET-1 and VEGF levels in aorta roots. The atherosclerotic lesions in aorta roots were analyzed with oil red O staining.

RESULTS

(1) The selenium concentrations in heart and liver were significantly higher in high dosage and low dosage selenium supplement groups compared to control group (both P<0.05). (2) The levels of triglyceride, total cholesterol, low density lipoprotein cholesterol, very low density lipoprotein cholesterol and high-density lipoprotein cholesterol were similar among groups (all P>0.05). (3) The activity levels of serum SOD were significantly higher in low dosage ((113.8±12.5)U/ml) and high dosage selenium supplement group ((152.3±11.3)U/ml) compared to control group ((90.7±10.7)U/ml, all P<0.05). The activity levels of serum GSH-Px were significantly higher in low dosage ((53.9±7.2)U/ml) and high dosage ((69.6±8.7)U/ml) selenium supplement groups than that of control group ((36.4±5.6)U/ml, all P<0.05). The serum MDA levels in low dosage ((4.73±1.05)nmol/ml) and high dosage ((4.13±1.21)nmol/ml) selenium supplement groups were significantly lower than that of control group ((5.97±1.08)nmol/ml, all P<0.05). (4) The serum NO concentrations in low dosage ((61.5±12.8)μmol/L) and high dosage ((79.0±14.6)μmol/L)selenium supplement groups were significantly higher than that of control group((42.7±9.1)μmol/L, all P<0.05). The concentrations of serum ET-1 in low dosage ((52.8±6.3)ng/L)and high dosage ((46.3±4.7)ng/L)selenium supplement groups were significantly lower than that of control group((72.2±6.3)ng/L, P<0.05). The concentrations of serum VEGF in low dosage ((97.4±16.5)ng/L)and high dosage ((83.5±22.0)ng/L)selenium supplement groups were significantly lower than that of control group((125.8±18.6)ng/L, P<0.05). The expression levels of ET-1 and VEGF in aorta roots among low dosage and high dosage selenium supplement groups were significantly lower compared to control group (all P<0.05). (5) The plaque area of aorta roots in low dosage ((0.95±0.19)×10(5) μm(2))and high dosage selenium supplement ((0.75±0.15)×10(5) μm(2)) groups were significantly smaller than that of control group((1.13±0.23)×10(5) μm(2)), and the plaque area in high dosage selenium supplement group was significantly smaller than in low dosage selenium supplement group (P<0.05).

CONCLUSION

Supplement of selenium can attenuate atherogenesis in ApoE-knockout mice fed high fat diet, which is possibly mediated via reducing lipid peroxidation and improving endothelial functions.

Delayed signal transmission in area 17, area 18 and the posteromedial lateral suprasylvian area of aged cats

To investigate the effect of senescence on signal transmission, we have compared the visual response latency and spontaneous activity of cells in the lateral geniculate nucleus (LGN), area 17, area 18 and posteromedial lateral suprasylvian area (PMLS) of young and old cats. We found that LGN cells in old cats exhibit largely normal visual response latency. In contrast, all the other three areas exhibited significant aging-related delays in the visual response latency. On average, PMLS showed most pronounced delays among these three areas. Area 18 slowed more than area 17, but this was not significant. The degradation of signal timing in the visual cortex might provide insight into neuronal response mechanism underlying perception slowing during aging.

Are psychiatrists' characteristics related to how they care for depression in the medically ill? Results from a national case-vignette survey

The authors' goal was to examine the relationship between psychiatrists' characteristics and their decisions regarding depression care. A national sampling of 278 psychiatrists answered diagnosis and treatment questions for one of four case vignettes with depression and various degrees of medical comorbidity. They also responded to a questionnaire assessing practice and demographic characteristics. Tendency to diagnose major depression was significantly associated with being board certified, being in practice for less time, having a greater percentage of patients with managed care, and having a greater percentage of patients on psychotropic medications. Tendency to recommend an antidepressant was significantly associated with the psychiatrist being male, being less satisfied with practice, and having a greater percentage of patients on psychotropic medications. These findings remained significant even after controlling for case characteristics. Diagnostic and prescribing tendencies of psychiatrists appear to be associated with specific physician characteristics and not simply case characteristics. These findings have implications for further studies of predictors of quality of care.

Spontaneous plaque rupture and secondary thrombosis in apolipoprotein E-deficient and LDL receptor-deficient mice

Apolipoprotein E-deficient (apoE(-/-)) and LDL receptor-deficient (LDLR(-/-)) mice develop extensive atherosclerosis, but the occurrence of spontaneous plaque rupture and secondary thrombosis in these models has not been established. The goal of this study was to provide histological evidence of acute complications of atherosclerotic lesions in these mice and to assess their prevalence. Complications of atherosclerosis were initially studied in aortas of control mice which died during previous intervention studies. Coronary arteries and the aortic origin were then systematically assessed in serial sections through the heart of apoE(-/-) and LDLR(-/-) mice. Aortic plaque rupture and/or thrombi were seen in 3 of 82 untreated mice from past intervention studies. Screening of heart sections of 33 older apoE(-/-) mice (age 9-20 months) showed extensive atherosclerosis in one or more coronary arteries of 18 animals. In three coronary arteries, the presence of blood-filled channels within advanced atherosclerotic lesions suggested previous plaque disruption/thrombotic events followed by recanalization. In the aortic origin of the same mice, four deep plaque ruptures (or erosions reaching necrotic core areas) and a large thrombus originating from the core of a disrupted atherosclerotic lesion were observed. Although plaque ruptures/deep erosions were far less frequent than in human populations, these observations demonstrate that spontaneous plaque rupture and secondary thrombosis do occur in apoE(-/-) and LDLR(-/-) mice. These mice may therefore be suitable for studying factors contributing to thrombotic complications of atherosclerosis. However, the frequent absence of a clearly defined single fibrous cap in murine coronary lesions limits their usefulness as a model of fibrous cap rupture.

Oscillatory electroosmosis-enhanced intra/inter-particle liquid transport and its primary applications in the preparative electrochromatography of proteins

The concept of generating an oscillatory electroosmotic flux inside the porous particle to enhance the intra-particle mass transport was presented and a new kind of electrochromatography carried out in a five-compartment electrolyzer were developed. The adsorbent was packed in the central compartment, while the neighboring compartments were used as the elution compartments and the electrode compartments, respectively. Chromatographic separations of human serum albumin on Blue Sepharose Fast Flow, bovine serum albumin (BSA) on DEAE-Sepharose Fast Flow, and BSA on hydroxyapatite were carried out, respectively. The adsorption isotherms were shown to be independent of electric field, while the increase in the electric field strength resulted in a linear increase in the magnitude of electroosmotic flux and the improvement of the breakthrough behavior in all cases. The experiment results have demonstrated the effectiveness of the oscillatory electroosmosis in enhancing intra- and inter-particle mass transport and its high potential to large-scale chromatography.

Mass transport characteristics and chromatographic behavior of preparative electrochromatography on hydroxyapatite

Introducing an electric field into chromatography on hydroxyapatite (HAP) was attempted in order to enhance mass transfer and separation performance. A membrane spaced multicompartment electrolyzer was developed for electrochromatography on HAP. The high performance of liquid transport by electroosmotic flux was identified and described in terms of dynamic electroosmotic pressure. The application of the electric field resulted in an improved adsorption of bovine serum albumin as shown by the breakthrough curve as function of the electric field. An improved elution was also obtained in the presence of the electric field. The results show that electroosmosis is a powerful tool of liquid transport and dispersion in a packed bed of fine particles and has potential in the large-scale chromatography of biological molecules.

Electrophoretic affinity chromatography: method validation

A new method for preparative-scale separation of biomolecules, electrophoretic affinity chromatography (EAC), is proposed in this paper. Separation by EAC is carried out in a long and ribbon-like multicompartment electrolyser separated by membranes, in which the two central compartments are used for packing the gel matrix and for sample loading respectively. Next to the central compartments are the elution compartments and electrode compartments. The electric field is applied perpendicular to the fluid flow in the compartments. Adsorption and desorption steps may both be carried out in the presence of an electric field, which transports the target components into the gel compartment for adsorption and the impurities into the elution compartments for washing. After the adsorption step an elution solution is introduced and the product is released from the gel matrix and washed out. Separation of human serum albumin (HSA) from human serum gives HSA product of high purity, as demonstrated by isoelectric focusing analysis. The characteristics of electrophoretic binding of HSA on Blue Sepharose Fast Flow are examined. The preliminary results show that this new method has advantages in terms of high rate of mass transfer and ease of scaling up, which are of particular interest when large-scale separation of biomolecules is considered.

Application of multichannel flow electrophoresis to separation of biomolecules: a survey

Multichannel flow electrophoresis (MFE) is a newly developed method for continuous separation of biological products at a preparative scale, In this short survey, the application of MFE in the separation of proteins, enzymes and antibodies are overviewed.

Inhibition of NOS enhances pulmonary vascular changes in stroke-prone spontaneously hypertensive rats

To determine the effects of chronic nitric oxide (NO) blockade on the pulmonary vasculature, 58-day-old spontaneously hypertensive rats of the stroke-prone substrain (SHRSP) and Wistar-Kyoto rats (WKY) received N(omega)-nitro-L-arginine (L-NNA; 15 mg. kg(-1). day(-1) orally for 8 days). Relaxation to acetylcholine (ACh) in hilar pulmonary arteries (PAs), the ratio of right ventricular (RV) to body weight (RV/BW) to assess RV hypertrophy (RVH), and the percent medial wall thickness (WT) of resistance PAs were examined. L-NNA did not alter the PA relaxation, RV/BW, or WT in WKY. Although the PA relaxation and RV/BW in control SHRSP were comparable to those in WKY, the WT was increased (31 +/- 2 vs. 19 +/- 1%). L-NNA-treated SHRSP showed two patterns: in one group, the relaxation, RV/BW, and WT were comparable to those in the control SHRSP; in the other, impaired relaxation (36 +/- 7 vs. 88 +/- 4% for WKY) was associated with an increase in WT (37 +/- 1%) and RV/BW (0. 76 +/- 0.05). Thus the abnormal pulmonary vasculature in SHRSP at <10 wk of age is not accompanied by impaired relaxation in PAs or RVH; however, impaired relaxation is associated with increased WT and RVH.

Experimental studies on affinity chromatography in an electric field

A multicompartment electrolyzer, which has been used for preparative electrophoresis [Z. Liu, Z. Huang, J.-Y. Cong, et al., Sep. Sci. Technol. 31 (1996) 427], is applied for carrying out affinity chromatography in an alternating electric field. The effect of electric field strength on the adsorption and desorption characteristics is experimentally examined with human serum albumin and Blue Sepharose Fast Flow as a model system. It is shown that the existence of an electric field leads to a significant change in the adsorption capacity of the blue dye, which may be used for establishing a preferential adsorption to achieve a high resolution. The adsorption speed increases slightly with respect to the increase of electric field strength, while adsorption capacity in the presence of an electric field is independent of the electric field strength. Different elution behavior is observed as function of adsorption condition and a high recovery of the adsorbed protein is obtained when the adsorption is carried out in the presence of an electric field.

Monocrotaline induces interleukin-6 mRNA expression in rat lungs

Monocrotaline-induced pulmonary hypertension (PH) in rats is preceded by an inflammatory response in the lungs, and interleukin-6 (IL-6) is expressed in response to inflammation. To evaluate the role of IL-6 in monocrotaline-induced PH, rats received a single subcutaneous injection of monocrotaline (60 mg/kg) or an equivalent amount of normal saline. Pulmonary artery pressure (Ppa), right ventricular hypertrophy (RVH), expression of IL-6 mRNA, and bioactivity of IL-6 in the lungs of these rats were examined 48 hours and 1 and 2 weeks after administration of monocrotaline. The effects of dexamethasone treatment on monocrotaline-induced PH also were evaluated. Two weeks after administration of monocrotaline, significant PH and RVH developed in these rats. Reverse transcription-polymerase chain reaction (RT-PCR) revealed expression of IL-6 mRNA in the lungs 48 hours and 1 and 2 weeks after administration of monocrotaline. This was confirmed using ribonuclease protection assay. The bioactivity of IL-6 in lung extracts progressively increased. Dexamethasone markedly inhibited expression of IL-6 mRNA and IL-6 bioactivity in the lungs, with concomitant attenuation of monocrotaline-induced PH and RVH. Our data show that monocrotaline induces expression of IL-6 mRNA in rat lungs and that inhibition of IL-6 results in attenuation of PH. These findings indicate that IL-6 may play a role in the pathogenesis of PH.

Assessing traumatic event exposure: general issues and preliminary findings for the Stressful Life Events Screening Questionnaire

This article reviews the psychometric properties of the Stressful Life Events Screening Questionnaire (SLESQ), a recently developed trauma history screening measure, and discusses the complexities involved in assessing trauma exposure. There are relatively few general measures of exposure to a variety of types of traumatic events, and most of those that exist have not been subjected to rigorous psychometric evaluation. The SLESQ showed good test-retest reliability, with a median kappa of .73, adequate convergent validity (with a lengthier interview) with a median kappa of .64, and good discrimination between Criterion A and non-Criterion A events. The discussion addresses some of the challenges of assessing traumatic event exposure along the dimensions of defining traumatic events, assessment methodologies, reporting consistency, and incident validation.

[Study of a new type of material substituted for human hard tissues-hydroxyl poly calcium sodium phosphate: histologic report implants in mandible of animals]

This study was aimed to evaluate the histocompatibility of hydroxyl poly calcium sodium phosphate (HPPA) preliminarily. HPPA and hydroxylapatite were implanted in the mandibular defect in dogs. The implant-bone interface was observed by using stereomicroscope and decalcified histologic sections. The result demonstrates that HPPA has well-osseous integrated property after being implanted into bone tissues. This suggests that HPPA might be a new material of future excellence in substitution for human hard tissues.

Multichannel flow electrophoresis and its applications in purification of proteins, enzymes, and antibodies

Multichannel flow electrophoresis (MFE) is a novel preparative electrophoresis technique designed for continuous separation of proteins based on their different isoelectric points. A computer controlled MFE apparatus is developed and the effects of operation parameters such as electric field strength, buffering pH, and sample introducing flow rate on MFE separation efficiency are investigated. The application of MFE is first exemplified by continuous separation of BSA and HBB mixture. Then continuous purification of urokinase from urine extracts is conducted, in which 10 x 10(4) IU urokinase product whose specific activity is higher than 40,000 IU/mg is obtained per hour. Finally, MFE is applied in the continuous purification of anti-urokinase mouse IgG from mouse serum and yields 2.1 mg mouse IgG per hour with high purity demonstrated by SDS-PAGE. The preliminary results presented have confirmed the workability of MFE and pointed out its high application potential in biochemical process.

cAMP-dependent protein kinase and protein kinase C consensus site mutations of the beta-adrenergic receptor. Effect on desensitization and stimulation of adenylylcyclase

Activation of cAMP-dependent protein kinase (cAPK) or protein kinase C (PKC) causes a rapid desensitization of beta 2-adrenergic receptor (beta AR) stimulation of adenylylcyclase in L cells, which previous studies suggest involves the cAPK/PKC consensus phosphorylation site in the third intracellular loop of the beta AR, RRSSK263. To determine the role of the individual serines in the cAPK- and PKC-mediated desensitizations, wild type (WT) and mutant beta ARs containing the substitutions, Ser261-->Ala, Ser262-->Ala, Ser262-->Asp, and Ser261/262-->Ala, were constructed and stably transfected into L cells. Results showed that serine 262 was the primary site of the cAPK-induced desensitization, whereas either serine 261 or serine 262 was sufficient to confer the 4 beta-phorbol 12 beta-myristate 13 alpha-acetate (PMA)/PKC-mediated desensitization. Coincident stimulation of cAPK and PKC caused an additive desensitization (6-8-fold increase in the EC50) which was significantly reduced (80%) only by the double substitution mutation. Quantitative evaluation of the coupling efficiencies and the GTP-shift of the WT and mutant receptors demonstrated that only one of the mutants, Ser262-->Ala, was partially uncoupled. The Ser262-->Asp mutation did not significantly uncouple, demonstrating that introducing a negative charge did not appear to mimic the desensitized state of the receptor. The beta AR expression level played a critical role in determining the pattern of beta AR desensitization; i.e. while the overall desensitization was unaltered within a large range of beta AR expression level (10-300 fmol/mg), the increase in EC50 and decrease in Vmax were differentially affected by the change in the receptor level.

Differential expression of the beta-adrenergic receptor modifies agonist stimulation of adenylyl cyclase: a quantitative evaluation

The effect of varying levels of beta 2-adrenergic receptor (beta AR) expression on the capacity of the receptor to activate adenylyl cyclase through regulatory G proteins has been systematically explored in this paper, using differential expression of hamster and human beta AR in L cells. Equations have been developed based on the cycle of G protein activation first proposed by Cassel and Selinger and the mobile receptor model, which assumes that hormone-bound beta AR can stimulate a number of different adenylyl cyclase moieties through the G protein during a single cycle of activation. These equations predict the relationship of receptor number to the EC50 (potency) and Vmax (efficacy) for adenylyl cyclase activation. L cell clones were selected with stable expression of the beta AR over a 2000-fold range of levels (from 5 to 10,000 fmol/mg of membrane protein). Experimentally determined values for the EC50 and the Vmax for epinephrine stimulation of adenylyl cyclase over the entire range of receptor levels were found to be in excellent agreement with predictions of the traditionally accepted models. A method is introduced that allows calculation of beta AR coupling efficiency while taking into account the effect of variable receptor levels. The approach provides a quantitative means for the determination of coupling efficiency of the receptor/G protein/adenylyl cyclase system over wide variations in receptor levels and allows for a rational comparison of coupling efficiencies of wild-type and mutant receptors when receptor levels differ.

Residual H2O2 compromises deswelling function of in vivo rabbit cornea

The purpose of the study was to investigate the effect of H2O2 on corneal swelling, corneal deswelling and to determine the concentration of H2O2 in the aqueous humor. Four types of experiments were performed using the rabbit eye. 1. Central corneal thickness (CCT) measurements after instillation of H2O2 into the cul-de-sac and after wearing H2O2 soaked soft contact lenses (SLC) for 2 h using 60 ppm, 100 ppm and 300 ppm H2O2. 2. Measurement of corneal deswelling induced by wearing SCL and closed eye for 2 h. 3. Determining the H2O2 in the aqueous humor one h after instillation of H2O2 into the cul-de-sac. CCT increases of 7.5% and 10.7% were found after the instillation of 100 ppm and 300 ppm H2O2 into the cul-de-sac. After wearing H2O2 soaked SCLs, CCT increased 4.6% and 5.8%, respectively. The H2O2 in the aqueous humor was 0.087 mM or a 160% increase after using 300 ppm H2O2. The increase in CCT and interference with the deswelling process is interpreted as a toxic effect on the cornea and an interference with the normal dehydration function of the endothelial pump.

The influence of adaptation on the oscillatory potentials of the human electroretinogram

The influence of adaptation on the oscillatory potentials of the human electroretinogram was studied in the domains of frequency and time. The amplitude of OP1 to OP4, the summed amplitude of OP1 to OP4, as well as the area, decreased from dark adaptation to light adaptation. With increasing intensities of background illumination, they increased slightly and appeared to decrease with the strongest background illumination. The implicit time of oscillatory potentials 3 and 4 increased with stronger background illumination and decreased with the strongest background illumination. The results of the dominant frequency and the total power of the OPs correspond to the results in the time domain. The dominant power decreased from dark adaptation into light adaptation and did not show any systematic changes with increasing intensity of background illumination.

Measurement of the oscillatory potential of the electroretinogram in the domains of frequency and time

The dark-adapted and light-adapted electroretinograms of 13 subjects with 23 normal eyes were analyzed by means of Fourier spectrum. The oscillatory potentials in the time domain were filtered out from the electroretinogram after a corresponding bandpass was given in the frequency domain. The coefficient of variation of total power, dominant power and dominant frequency of the isolated oscillatory potentials in the frequency domain, summed amplitudes and area of the isolated oscillatory potentials, each amplitude and implicit time of the first four major oscillatory potential wavelets in the time domain were compared. The implicit time showed the smallest coefficient of variation; summed amplitudes of OP1 to OP4 showed smaller coefficients of variation than those of the area, the amplitude of each oscillatory potential wavelet, dominant frequency and dominant and total power. The coefficient of variation of these measurement parameters in light-adapted electroretinograms was smaller than those in dark-adapted electroretinograms.

Regulation of renal Na(+)-H+ exchanger by cAMP-dependent protein kinase

Octyl glucoside-extracted rabbit renal brush-border membrane (BBM) proteins were sequentially fractionated using anion exchange chromatography, and the fractions were tested for Na(+)-H+ exchange activity, amiloride sensitivity, and the effect of adenosine 3',5'-cyclic monophosphate (cAMP)-dependent protein kinase (PKA) after reconstitution into artificial lipid vesicles. Compared with the initial protein extract, an anionic protein fraction eluting with 0.2-0.4 M NaCl (fraction B) demonstrated increased Na(+)-H+ exchange activity. Fraction B also demonstrated sensitivity to inhibition by amiloride but was not regulated by PKA. Co-reconstitution of fraction B with a BBM protein fraction highly enriched in a 42-kDa polypeptide restored the inhibitory response to PKA. These experiments suggest that, as assayed in a solubilized and reconstituted system, the Na(+)-H+ exchanger contains a dissociable PKA regulatory component, possibly a polypeptide of 42 kDa.