Evolution of compressive mechanical properties of early hypertrophic scar during laser treatment

Laser therapy has been widely used in the treatment of hypertrophic scars (HPS), but whether the mechanical properties of HPS tissue after laser treatment can be restored to those of normal skin remains unclear. In this paper, the relationship between the evolution of compressive mechanical properties and histological changes of HPS tissues following three successive combined pulsed dye laser (PDL) and fractional CO₂ laser (CO₂) treatments was investigated by compression tests and histological analysis. The early HPS model of rabbit ear was established by CO₂ laser ablation. The loading-unloading tests and strain creep tests under the compression forces of 1 N, 2 N, and 3 N were carried out for normal skin, untreated HPS and HPS after different treatment times, respectively. The results showed that the compression ratio λ of all tissues revealed force dependence and rose with the increasing compression force, which was similar to the trend of most biological soft tissues. The histological changes of HPSs following laser treatment have a significant influence on the compressive mechanical response. Compared with the normal skin, the toughness and anti-deformation ability of HPS reduced due to the proliferation of collagen fibers and the destruction of elastic fibers, resulting in higher energy dissipation, compression ratio λ, and stable creep rate D, and lower elastic modulus. After three successive combined PDL/ CO₂ laser treatments, the compressive mechanical properties and creep properties of HPS gradually approached that of the normal skin owing to the gradual restoration of the amount and distribution of collagen and elastic fibers in HPS. The results provide a new method for evaluating the clinical efficacy of laser therapy for treatment of HPS tissue.

[Clinical effect of adding hMG to the follicular phase long protocol for standard group with normal ovarian reserve function]

Objective: To investigate the impact of adding human menopausal gonadotropin (hMG) for in vitro fertilization-embryo transfer pregnancy outcomes in a standard population of non-advanced age with normal ovarian reserve function using a long follicular phase protocol. Methods: Clinical data of 489 patients with normal ovarian reserve function, who were admitted from January 2018 to January 2020 in the Affiliated Hospital of Guizhou Medical University and underwent in vitro fertilization for the first time with the long follicular phase protocol in fresh cycles, were retrospectively analyzed. The patients were divided into three groups according to whether or not to add urine-derived hMG and the timing of addition: non-addition group (group A), medium-term hMG group (group B1), whole course hMG group (group B2); the laboratory parameters of each group were observed, and the effect of ovulation induction drugs and pregnancy outcomes were compared. Results: The ages of B1 and B2 groups were significantly higher than that of group A (P=0.019 and P=0.011). The basal FSH level of group B2 was significantly higher than those of group A and group B1 (P<0.01 and P=0.006), and the basal FSH/LH ratio of group B2 was significantly higher than that of group B1 (P=0.009). Antral follicle counts of group A and group B1 were significantly higher than that of group B2 (P=0.007 and P=0.017). The superior embryo rate of group B2 [(47±27)%] was significantly higher than that of group A (P=0.017). The embryo implantation rate of group B1 was significantly lower than those of group A and group B2 (P=0.043 and P<0.01). The clinical pregnancy rate of group B2 [76.7% (155/202)] was significantly higher than those of group A (P=0.039) and group B1 (P<0.01). The live-birth rate of group B2 [67.3% (136/202)] was significantly higher than those of group A (P=0.017) and group B1 (P=0.001). Conclusions: For non-advanced aged patients with normal ovarian reserve function, the long protocol of follicular phase is suitable for those with relatively low ovarian reserve function. Adding hMG in the whole course of ovulation induction after gonadotropin-releasing hormone agonist reduction could improve the pregnancy outcomes by improving the quality of embryos.

The Molecular Mechanism of Chronic High-Dose Corticosterone-Induced Aggravation of Cognitive Impairment in APP/PS1 Transgenic Mice

Clinical studies have found that some Alzheimer’s disease (AD) patients suffer from Cushing’s syndrome (CS). CS is caused by the long-term release of excess glucocorticoids (GCs) from the adrenal gland, which in turn, impair brain function and induce dementia. Thus, we investigated the mechanism of the effect of corticosterone (CORT) on the development and progression of AD in a preclinical model. Specifically, the plasma CORT levels of 9-month-old APP/PS1 Tg mice were abnormally increased, suggesting an association between GCs and AD. Long-term administration of CORT accelerated cognitive dysfunction by increasing the production and deposition of β-amyloid (Aβ). The mechanism of action of CORT treatment involved stimulation of the expression of BACE-1 and presenilin (PS) 1 in in vitro and in vivo. This observation was confirmed in mice with adrenalectomy (ADX), which had lower levels of GCs. Moreover, the glucocorticoid receptor (GR) mediated the effects of CORT on the stimulation of the expression of BACE-1 and PS1 via the PKA and CREB pathways in neuroblastoma N2a cells. In addition to these mechanisms, CORT can induce a cognitive decline in APP/PS1 Tg mice by inducing apoptosis and decreasing the differentiation of neurons.

[The value of intraoperative cerebral oxygen saturation in predicting postoperative neurocognitive dysfunction in elderly patients with mild cognitive impairment]

Objective: To evaluate the value of intraoperative cerebral oxygen saturation in predicting postoperative neurocognitive dysfunction (PND) in elderly patients with mild cognitive impairment. Methods: A total of 210 cases of lumbar decompression, bone grafting and fusion surgery under general anesthesia were collected in the Third Central Hospital of Tianjin from June, 2019 to January, 2020, either sex, aged 65-75 year, BMI 19.5-32.5 kg/m(2), ASA physical status Ⅱ or Ⅲ, preoperative comorbidities with mild cognitive impairment. MoCA and MMSE were used to evaluate the cognitive function of patients 1 day before the operation, 7 days and 3 monthes after operation. PND group (n=38) and non-PND group (n=172) were selected according to postoperative MMSE and MoCA scale scores and the diagnostic criteria of PND. Heart rate (HR) , mean arterial pressure (MAP), pulse oxygen saturation (SpO(2)), bispectral index (BIS), cerebral tissue oxygen saturation (SctO(2), average left and right brain SctO(2) were recorded) were recorded pre-anesthetic (T(0)), ten minutes of anesthesia(T(1)), twenty minutes of anesthesia (T(2)), thirty minutes into the operation (T(3)), one hour into the operation (T(4)), end of the surgery (T(5)), and leave the PACU (T(6)). SctO(2) at time point T(0) was the base value of SctO(2), and the maximum percentage drop in SctO(2) from the base value was calculated (SctO(2max)%). Results: The incidence of PND was 18% (38/210) in 210 elderly patients undergoing surgery. The age of PND group and non-PND group was (71.0±2.1) and (67.8±2.0) years old, and the PACU time was (57±5) and (46±8) min, respectively. Compared with the non-PND group, the age of the PND group was higher (t=2.600, P<0.05) and the PACU time was longer (t=3.039, P<0.05). At the time points T(3), T(4), T(5) and T(6), SctO(2) in the PND group was (62±10) %, (60±11) %, (64±12) % and (66±10)%, respectively, lower than that in the non-PND group (67±60) %, (68±6) %, (69±5) % and (70±7)%, respectively, and the difference was statistically significant (t=3.369, 4.906, 3.787, 2.516, all P<0.05).The MoCA and MMSE scores of the PND group were (22.9±1.2) and (24.1±1.2) points, respectively, 1 day before surgery; and the MoCA and MMSE scores of the PND group were reduced to (20.8±1.2) and (21.3±0.7) points, respectively, 7 days after surgery, with statistically significant differences (t=3.523, 5.675, all P<0.05). MoCA and MMSE scores 7 days after surgery in the non-PND group were (22.4±1.3) and (23.1±1.6) points, respectively. Compared with the non-PND group, MoCA and MMSE scores 7 days after surgery in the PND group were reduced (t=2.630, 3.108, all P<0.05). The critical value of intraoperative SctO(2max)% was 13.74%, the area under the curve of PND was predicted to be 0.907 (95%CI: 0.819-0.995), sensitivity and specificity were 88.9% and 88.5%, respectively. Conclusion: SctO(2max)%>13.74% can be used as an indicator to predict PND occurrence in elderly patients with mild cognitive impairment during lumbar surgery.

Cyclooxygenase-2 is Essential for Mediating the Effects of Calcium Ions on Stimulating Phosphorylation of Tau at the Sites of Ser 396 and Ser 404

Alzheimer's disease (AD) is reported to be associated with the accumulation of calcium ions (Ca2+), which is responsible for the phosphorylation of tau. Although a series of evidence have demonstrated this phenomenon, the inherent mechanisms remain unknown. Using tauP301S and cyclooxygenase-2 (COX-2) transgenic mice and neuroblastoma (n)2a cells as in vivo and in vitro experimental models, we found that Ca2+ stimulates the phosphorylation of tau by activating COX-2 in a prostaglandin (PG) E2-dependent EP receptor-activating manner. Specifically, Ca2+ incubation stimulated COX-2 and PGE2 synthase activity, microsomal PGE synthase 1 and the synthesis of PGE2 by activating the transcriptional activity of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) in n2a cells. Elevated levels of PGE2 were responsible for phosphorylating tau in an EP-1, -2, and -3 but not EP4-dependent glycogen synthase kinase 3-activating manner. These observations were corroborated by results that showed tau was phosphorylated when it colocalized with activated COX-2 in tauP301S and COX-2 transgenic mice or n2a cells. To further validate these observations, treatment of mice with the COX-2 inhibitor rofecoxib decreased the phosphorylation of tau via EP1-3 but not EP4. Collectively, our observations fill the gaps between Ca2+ and the phosphorylation of tau in a COX-2-dependent mechanism, which potentially provides therapeutic targets for combating AD.

Research Progress on the Relationship between Genetic Polymorphism and Violent Behavior of Patients with Schizophrenia

Abstract

Schizophrenia is a common disease characterized by thinking obstructions and accompanied by cognitive, emotional and behavioral disorders. Under the control of psychiatric symptoms, patients with schizophrenia may self-injure or impulsively wound others, resulting in public risk and increase in the burden of family and society. In recent years, many studies have shown that the violent behavior of patients with schizophrenia is related to genetic factors. This article reviews the research progress on the relationship between genetic polymorphism and violent behavior of patients with schizophrenia, analyzes the possible mechanism of the correlation between the two, puts forward the limitations of current research and the directions of future research, and provides scientific basis for risk assessment and prevention of violent behavior of patients with schizophrenia.

Cyclooxygenase-2 Induced the β-Amyloid Protein Deposition and Neuronal Apoptosis Via Upregulating the Synthesis of Prostaglandin E2 and 15-Deoxy-Δ12,14-prostaglandin J2

Elevated levels of cyclooxygenase-2 (COX-2) and prostaglandins (PGs) have been shown to be involved in the pathogenesis of Alzheimer's disease. Analysis of the underlying mechanisms elucidated a function of sequential PGE2 and PGD2 synthesis in regulating β-amyloid protein (Aβ) deposition by modulating tumor necrosis factor α (TNF-α)-dependent presenilin (PS)1/2 activity in COX-2 and APP/PS1 crossed mice. Specifically, COX-2 overexpression accelerates the expression of microsomal PGE synthase-1 (mPGES-1) and lipocalin-type prostaglandin D synthase (L-PGDS), leading to the synthesis of PGE2 and 15-deoxy-Δ12,14-prostaglandin J2 (15d-PGJ2) in 6-month-old APP/PS1 mice. Consequently, PGE2 has the ability to increase Aβ production by enhancing the expression of PS1/2 in a TNF-α-dependent manner, which accelerates the cognitive decline of COX-2/APP/PS1 mice. More interestingly, low concentrations of 15d-PGJ2 treatment facilitate the effects of PGE2 on the deposition of Aβ via TNF-α-dependent PS1/2 mechanisms. In contrast, high concentrations of 15d-PGJ2 treatment inhibit the deposition of Aβ via suppressing the expression of TNF-α-dependent PS1/2. In this regard, a high concentration of 15d-PGJ2 appears to be a therapeutic agent against Alzheimer's disease. However, the high 15d-PGJ2 concentration treatment induces neuronal apoptosis via increasing the protein levels of Bax, cleaved caspase-3, and DFF45, which further impairs the learning ability of APP/PS1 mice.

Calcium Ions Stimulate the Hyperphosphorylation of Tau by Activating Microsomal Prostaglandin E Synthase 1

Alzheimer’s disease (AD) is reportedly associated with the accumulation of calcium ions (Ca²⁺), and this accumulation is responsible for the phosphorylation of tau. Although several lines of evidence demonstrate the above phenomenon, the inherent mechanisms remain unknown. Using APP/PS1 Tg mice and neuroblastoma (N)2a cells as in vivo and in vitro experimental models, we observed that Ca²⁺ stimulated the phosphorylation of tau by activating microsomal PGE synthase 1 (mPGES1) in a prostaglandin (PG) E₂-dependent EP receptor-activating manner. Specifically, the highly accumulated Ca²⁺ stimulated the expression of mPGES1 and the synthesis of PGE₂. Treatment with the inhibitor of Ca²⁺ transporter, NMDAR, attenuated the expression of mPGES1 and the production of PGE₂ were attenuated in S(+)-ketamine-treated APP/PS1 Tg mice. Elevated levels of PGE₂ were responsible for the hyperphosphorylation of tau in an EP-1-, EP-2-, and EP-3-dependent but not EP4-dependent cyclin-dependent kinase (Cdk) 5-activating manner. Reciprocally, the knockdown of the expression of mPGES1 ameliorated the expected cognitive decline by inhibiting the phosphorylation of tau in APP/PS1 Tg mice. Moreover, CDK5 was found to be located downstream of EP1-3 to regulate the phosphorylation of tau though the cleavage of p35 to p25. Finally, the phosphorylation of tau by Ca²⁺ contributed to the cognitive decline of APP/PS1 Tg mice.

[Uvuplopalatal flap in OSAHS patients with anteriorand posterior pharyngeal plane stenosis]

Objective: Observation of the effect of uvuplopalatal flap for OSAHS patients with anterior and posterior pharyngeal stenosis. Method: Fifty-six patients with OSAHS who were mainly anterior posterior stenosis in the velopharyngeal plane were selected. Patients with suspending uvuplopalatal flap were used as observation group (30 cases). Patients with UPPP were used as control group (26 cases). The investigation and comparison of AHI, SaO₂, scars, throat foreign body sensation, pharynx desiccation, pharynx' s tightness, pharynx discomfort and surgical satisfaction were investigated at 6-8 months after the operation. Restul: At 6-8 months after operation, the AHI and SaO₂ of the two groups were significantly improved compared with those before operation(P<0.01). However, there were significant differences(P<0.01) among the indexes of scar formation, throat foreign body, sensation pharynx desiccation, pharynx' s tightness, pharynx discomfort and surgical satisfaction. Conclusion: In the OSAHS patients with anterior and posterior pharyngeal stenosis, the effect of UPF was better than that of UPPP among the indexes of scar formation, pharyngeal symptoms and surgical satisfaction.

Magnesium Ions Inhibit the Expression of Tumor Necrosis Factor α and the Activity of γ-Secretase in a β-Amyloid Protein-Dependent Mechanism in APP/PS1 Transgenic Mice

Alzheimer’s disease (AD) is a neurodegenerative disease characterized by cognitive impairment. The neuropathological features of AD are the aggregation of extracellular amyloid β-protein (Aβ) and tau phosphorylation. Recently, AD was found to be associated with magnesium ion (Mg²⁺) deficit and tumor necrosis factor-alpha (TNF-α) elevation in the serum or brains of AD patients. To study the relationship between Mg²⁺ and TNF-α, we used human- or mouse-derived glial and neuronal cell lines or APP/PS1 transgenic (Tg) mice as in vitro and in vivo experimental models, respectively. Our data demonstrates that magnesium-L-threonate (MgT) can decrease the expression of TNF-α by restoring the levels of Mg²⁺ in glial cells. In addition, PI3-K/AKT and NF-κB signals play critical roles in mediating the effects of Mg²⁺ on suppressing the expression of TNF-α. In neurons, Mg²⁺ elevation showed similar suppressive effects on the expression of presenilin enhancer 2 (PEN2) and nicastrin (NCT) through a PI3-K/AKT and NF-κB-dependent mechanism. As the major components of γ-secretase, overexpression of presenilin 1 (PS1), PEN2 and NCT potentially promote the synthesis of Aβ, which in turn activates TNF-α in glial cells. Reciprocally, TNF-α stimulates the expression of PEN2 and NCT in neurons. The crosstalk between TNF-α and Aβ in glial cells and neurons could ultimately aggravate the development and progression of AD.

[Effects of functional training combined with self-made hand flexing training band in treatment of scar contracture after burn injury of dorsal hand]

Objective: To observe the effects of functional training combined with self-made hand flexing training band in treatment of scar contracture after burn injury of dorsal hand. Methods: Forty-six patients with scar contracture after deep partial-thickness or full-thickness burn injury of dorsal hand hospitalized in our department from March 2013 to February 2015 were divided into routine training group (RT, n=18) and comprehensive training group (CT, n=28) according to their willingness. Two weeks after the wounds were healed, patients in group RT were treated with functional training of hands and self-made pressure gloves, while patients in group CT were treated with self-made hand flexing training band (consisting of nylon strap, flexing band, and velcro) on the basis of those in group RT. All patients were treated for 3 months. Before and after treatment, scar condition of affected hands was assessed with Vancouver Scar Scale (VSS). The range of motion of joints of affected hands was measured by Total Active Movement (TAM) Scale. The function of affected hands was evaluated by Carroll Upper Extremity Function Test. Data were processed with t test, chi-square test, and Mann-Whitney U test. Results: (1) The score of VSS in patients of group RT was (10.0±1.9) points before treatment and (4.4±1.4) points after treatment, with the improved score of (5.6±1.0) points. The score of VSS in patients of group CT was (10.5±1.8) points before treatment and (4.6±1.4) points after treatment, with the improved score of (5.9±1.2) points. There was no statistically significant difference in the improved score of patients between the two groups (t=0.834, P>0.05). The score of VSS in patients of groups RT and CT after treatment was significantly lower than that before treatment (with t values respectively 14.014 and 10.003, P values below 0.01). (2) Before treatment, the ratios of excellent and good results according to TAM were 2/9 in patients of group RT and 3/14 in group CT, with no statistical differences between them (χ(2)=2.140, P>0.05). After treatment, the ratio of excellent and good results according to TAM in patients of group CT (6/7) was higher than that in group RT (5/9, χ(2)=0.023, P=0.038). The ratios of excellent and good results according to TAM in patients of groups RT and CT after treatment were significantly higher than those before treatment (with Z values respectively -2.023 and -4.780, P values below 0.05). (3) The improved score of hand function in patients of group CT was (26±12) points, which was higher than (15±7) points in group RT (t=3.278, P=0.002). The score of hand function in patients of groups RT and CT after treatment was significantly higher than that before treatment (with t values respectively 2.628 and 6.125, P values below 0.05). There were no significant differences in grades of hand function of patients between the two groups before treatment (Z=-0.286, P>0.05). After treatment, the grade of hand function in patients of group CT was higher than that in group RT(Z=-1.993, P=0.046). The grades of hand function in patients of groups RT and CT after treatment were significantly higher than those before treatment (with Z values respectively -2.717 and -4.998, P values below 0.01). Conclusions: For patients with scar contracture after burn injury of dorsal hand, early functional training combined with hand flexing training band can improve the range of motion of hand joints and functional recovery of hand, and the result was better than functional training alone.

Impact of human activities on subaqueous topographic change in Lingding Bay of the Pearl River estuary, China, during 1955-2013

Estuaries have been sites of intensive human activities during the past century. Tracing the evolution of subaqueous topography in estuaries on a decadal timescale enables us to understand the effects of human activities on estuaries. Bathymetric data from 1955 to 2010 show that land reclamation decreased the subaqueous area of Lingding Bay, in the Pearl River estuary, by ~170 km² and decreased its water volume by 615 × 10⁶ m³, representing a net decrease of 11.2 × 10⁶m³ per year and indicating the deposition of approximately 14.5 Mt/yr of sediment in Lingding Bay during that period. Whereas Lingding Bay was mainly governed by natural processes with slight net deposition before 1980, subsequent dredging and large port engineering projects changed the subaqueous topography of the bay by shallowing its shoals and deepening its troughs. Between 2012 and 2013, continuous dredging and a surge of sand excavation resulted in local changes in water depth of ± 5 m/yr, far exceeding the magnitude of natural topographic evolution in Lingding Bay. Reclamation, dredging, and navigation-channel projects removed 8.4 Mt/yr of sediment from Lingding Bay, representing 29% of the sediment input to the bay, and these activities have increased recently.

Efficacy of tension-free vaginal tape obturator and single-incision tension-free vaginal tape-Secur, hammock approach, in the treatment of stress urinary incontinence

AIM

Aim of the present study was to compare the efficacy of tension-free vaginal tape obturator and single-incision tension-free transvaginal tape Secur, hammock approach, in the treatment of stress urinary incontinence.

METHODS

Clinical data of patients who received anti-incontinence surgery between June 2008 and July 2012 were retrospectively analyzed. Efficacy and early failure rate of the tension-free vaginal tape obturator and tension-free vaginal tape-Secur hammock approach were assessed by cough test and criteria of International Consultation on Incontinence Questionnaire-Short Form. Intraoperative and postoperative complications were also computed.

RESULTS

There were 28 patients in the tension-free vaginal tape obturator group while 32 patients in the tension-free vaginal tape-Secur group. The mean operation time, intraoperative blood loss and inpatient days after surgery between the two groups showed no significant difference. The catheter retention time of the tension-free vaginal tape obturator group was longer than in the tension-free vaginal tape-Secur group. The cure rate of the tension-free vaginal tape obturator and tension-free vaginal tape-Secur groups were respectively 84% and 80%, and the recurrence rates were 14.3% and 16.7%, without significant difference. The scores of International Consultation on Incontinence Questionnaire-Short Form in two groups both decreased after surgery, but there was no difference between the two groups. There were no serious complications in the two groups.

CONCLUSION

Our study demonstrated that both tension-free vaginal tape obturator and tension-free vaginal tape-Secur can achieve a cure rate over 80% while with little complications, showing both methods are reliable to treat stress urinary incontinence.

Current through single conjugated molecules: calculations versus measurements

We use density functional theory based nonequilibrium Green's function to calculate the current through the different rodlike molecules at the finite temperatures self-consistently, which was compared to the experimental measurements presented by Reichert et al. [Phys. Rev. Lett. 88, 176804 (2002)] and by Mayor et al. [Angew. Chem. Int. Ed. 42, 5834 (2003)], respectively. Our results agree with the measurements very well, especially for the bias around +/-1.0 V. The investigation of the topological effect for the symmetrical molecule reveals the fact that the para position compound provides a considerably larger conductance than the meta one.

Ab initiostudy of single-molecule rotation switch based on nonequilibrium Green’s function theory

The bistable molecular switches have been studied theoretically based on the first-principles calculation. The geometry structures of the switches studied in this paper can be triggered between two symmetrical structures by using an external applied electric field. I-V characteristic curves of the different molecule configurations have been calculated, and distinguishability of these characteristic curves indicates a switching behavior, the performance of which can be improved significantly by some suitable donors and acceptors.

Role of propofol and its solvent, intralipid, in nitric oxide-induced peripheral vasodilatation in dogs

BACKGROUND

The commercial propofol preparation in an intralipid solution causes marked vasodilatation. Both propofol and its solvent seem to stimulate the nitric oxide (NO) pathway. The role of intralipid in cardiac and regional haemodynamic changes induced by propofol and their respective interactions with the NO pathway was assessed.

METHODS

Dogs were instrumented to record arterial pressure, heart rate, cardiac output, dP/dt (the first derivative of left ventricular pressure) and vertebral, carotid, coronary, mesenteric, hepatic, portal and renal blood flows. Experimental groups were as follows. Group 1 (control; n = 11): N-methyl-L-arginine (L-NMA) 20 mg kg-1 i.v.; Group 2 (n = 8): propofol (10 mg ml-1) 4 mg kg-1 i.v. bolus followed by 0.6 mg kg-1 min-1; Group 3 (n = 6): intralipid 0.25 ml kg-1 bolus followed by 0.06 ml kg-1 min-1. After 60 min, L-NMA was injected in Groups 2 and 3.

RESULTS

Propofol induced increases in heart rate, coronary and carotid blood flows, and decreases in systemic vascular resistance and dP/dt. Intralipid increased renal blood flow, carotid vascular resistance and mesenteric vascular resistance. In the presence of intralipid, L-NMA-induced pressor response and systemic, carotid and renal vasoconstriction were more pronounced than in control dogs.

CONCLUSIONS

Except for the coronary and carotid circulations, intralipid modulates the NO pathway in cardiac and regional blood flow.

[Regulation of Chinese medicine bailong and hexamethylene bisacetamide on cyclin dependent kinase inhibitor P16 genes in human cancer cell]

OBJECTIVE

To study the regulation of bailong, a Chinese herbal anticancer preparation and hexamethylene bisacetamide (HMBA) on cyclin dependent kinase inhibitor P16 (CKI-P16) genes in human cancer cells.

METHODS

The expression of CKI-P16 in different human cancer cells treated by Bailong or HMBA under different condition, was examined using Northern hybridization, Western blotting assay, etc.

RESULTS

After being treated by Bailong or HMBA, the P16 expression increased. This effect was closely related to co-regulation of cAMP-PKA and DAC-PKC signal pathway. When PKA pathway was blocked with PKA inhibitor, the P16 expression decreased, while PKC pathway was blocked, it enhanced.

CONCLUSION

(1) The low P16 expression in G1 phase of cancer cell, as compared with that in S, G2 and M phases, might be an important factor responsible to the incompetence of P16 in inhibiting effectively the malignant change of cancer cell. (2) Mechanism of Bailong and HMBA on cancer cell proliferation inhibition might be correlated with the enhancement of P16 expression in G1 phase of cancer cells. (3) Regulation and expression of Bailong and HMBA on P16 showed the common character of Chinese and western medicine in regulating cancer cells. (4) This study elucidated that upstream of P16 was related to cAMP/PKC signal pathway closely.

Role of heparin and nitric oxide in the cardiac and regional hemodynamic properties of protamine in conscious chronically instrumented dogs

BACKGROUND

Because protamine is administered to reverse heparin, a drug that might itself affect the pharmacologic properties of protamine, this study was designed to assess the properties of protamine alone and in the presence of heparin in conscious dogs.

METHODS

Twelve dogs were instrumented to continuously record cardiac and regional hemodynamics. On separate occasions, a dose of protamine (0.5, 1, 3, 5, and 8 mg/kg) was randomly administered either alone or in the presence of heparin (ratio 100 IU/mg). Heparin (300 IU/kg) and protamine (3 mg/kg) were administered in the presence of N-methyl-L-arginine, a specific nitric oxide synthase inhibitor. Identical experiments were performed with protamine (8 mg/kg) in the absence of heparin on a separate occasion.

RESULTS

Protamine alone produced limited cardiac and regional changes. In the presence of heparin, protamine produced hypotension at 3, 5, and 8 mg/kg, vasodilatation at 3 and 5 mg/kg, and a more pronounced dose-dependent increase in pulmonary pressure at 3, 5, and 8 mg/kg. Simultaneously, transient carotid vasodilatation at 3 and 5 mg/kg, coronary and hepatic vasodilatation at 3, 5, and 8 mg/kg, as well as a decrease in vertebral vascular resistance were recorded at 1, 3, and 8 mg/kg. Protamine produced an immediate increase followed by a secondary decrease in renal vascular resistance. Protamine-induced secondary pulmonary pressor effects were attenuated. In the presence of heparin, nitric oxide synthase blockade selectively attenuated protamine-induced immediate hypotension, systemic vasodilatation, and coronary, mesenteric, and hepatic vasodilations as well as the decrease in portal blood flow and accentuated the renal vasoconstriction.

CONCLUSIONS

The presence of heparin accentuated the decrease in cardiac function induced by protamine as well as its effects on regional circulation. The data provide evidence that the nitric oxide pathway is involved in the systemic and selective regional heparin-protamine-mediated vasodilatation in conscious dogs.

[Regulative effects of bailong and Hexamethylene bisacetamide on growth and phenotype of human gastric cancer cells in cell cycle]

OBJECTIVE

To investigate and compare the common effect of Bailong, a Chinese herbal preparation, and Hexamethylene bisacetamide (HMBA), a western cell differentiation inducer, on growth regulation and phenotype of human gastric cancer (MGC80-3) cells in different phases of cell cycle.

METHODS

Synchronized MGC80-3 cells in monolayer cultures with nitrous oxide under high pressure were double blocked with overdosage of TdR in the 4 cellular phases (G1, S, G2 and M), and then collected and treated with Bailong and 5 mmol/L HMBA respectively.

RESULTS

Both medicines could suppress the cell proliferation, soft agar cloning growth and microfilament assembling of different phases of cells, the effect on cells of G1 phase was the most significant one.

CONCLUSION

Bailong and HMBA had significant common characteristics in inducing cell differentiation of MGC80-3 cells in different phases of cell cycle.

[Study on common character of regulative molecular mechanism of Chinese drug bailong and hexamethylen bisacetamide in human cancer cell cycle and their oncogene and tumor suppressor gene expression]

OBJECTIVE

To investigate the common regulative effects of the Chinese drug Bailong and hexamethylen bisacetamide (HMBA) on expressions of oncogenes (c-H-ras and c-myc), and tumor suppressor genes (Rb, p53 and p21) of MGC80-3 in human cancer cell cycle.

METHODS

Adopting RNA Northern Blot to survey the levels of gene expressions of MGC80-3 different phases cells treated with Bailong and HMBA respectively.

RESULTS

In different phases of MGC80-3 cells treated with Bailong and differentiation inducer HMBA, expressions of oncogenes c-H-ras and c-myc were inhibited by over 50.0%, messenger kinase subspecies PKC-alpha gene is similar with the expression inhibition of oncogenes, except effect of Bailong on the G2 phase in cell cycle. Effect of Bailong differs greatly from HMBA in the expression of tumor suppression genes. The expression of Rb and p21 in cells treated by HMBA did not increase but were inhibited by 39.5% and 33.3% respectively in G1 phase. The level of Rb gene expression was decreased, too by 3.0% in S phase. Comparison with HMBA the expression of Rb and p21 genes were increased after treatment by Bailong in all cell cycle. But the effect of Bailong on the expression of p53 gene which was increased obviously by 125.0%-233.4% in majority phase of MGC80-3 cells is similar to HMBA.

CONCLUSION

(1) The effect of Bailong on the regulation of oncogenes and tumor suppressor gene is similar to HMBA but the effect of Bailong is better than that of HMBA. (2) Molecular mechanism of the Bailong or HMBA on the proliferative inhibition and differentiation of MGC80-3 related to regulation of the Bailong and HMBA on the oncogenes and tumor suppressor genes in cell cycle of MGC80-3.

[Characterization of cell death induced by anticancer antibiotic lidamycin in human hepatoma BEL-7402 cells]

AIM

To study the features of cell death induced by the anticancer antibiotic lidamycin (LDM) in human hepatoma BEL-7402 cells.

METHODS

Chromatin condensation was observed by co-staining with fluorescent dyes, hoechst 33342 and propidium iodide. "G1 sub-peak" was detected by flow cytometry and DNA ladder was observed using agarose gel electrophoresis. The caspase-3, 6 activities were measured with kits specific for them.

RESULTS

Typical apoptotic chromatin condensations appeared when the BEL-7402 cells were treated with the conventional antitumor agent mitomycin C30 mumol.L-1 for 12 h. However, an abnormal type of chromatin condensation occurred when the cells were treated with LDM 1 mumol.L-1 for 6 h, which was characterized with keeping the completeness of nuclear membrane and not forming apoptotic bodies. The DNA ladder patterns were observed using agarose gel electrophoresis. The "G1 sub-peak" occurred only in the cells treated with LDM for 24 h, though chromatin condensation was earlier detected in treatment with LDM for 6 h. The caspase-3, 6 activities were increased about 5 and 4 folds, after the cells were treated with LDM 1 mumol.L-1 for 6 h, as did mitomycin C. The time of initiating chromatin condensation was earlier than that of the high peak activities of caspase-6.

CONCLUSION

The characterization of cell death induced by lidamycin in the human hepatoma BEL-7402 cells differs from typical apoptosis. The results make it helpful to explain the molecular mechanism of the highly potent cytotoxicities of lidamycin toward tumor cells.

Effect of catecholamic acid on detoxication and distribution of NiCl2 in mice and rats

AIM

To study the effect of catecholamic acid (CBMIDA) on detoxication of NiCl2.

METHODS

Mice and rats were injected s.c. or i.m. CBMIDA immediately after i.p. NiCl2. Each mouse was injected i.p. CBMIDA after i.v. 63NiCl2 185 kBq, and radioactivities of various tissues were measured with liquid scintillation counter at 24 h. The localization of 63Ni was shown by the whole-body autoradiography.

RESULTS

CBMIDA s.c. 0.5-1.5 g.kg-1 markedly reduced the mortality from acute poisoning of i.p. NiCl2 500 mg.kg-1. After i.p. NiCl2 in mice, the LD50 was 82.7 mg.kg-1. Mice were injected s.c. CBMIDA 1.5 or 2.5 g.kg-1 after Ni poisoning, the LD50 of NiCl2 were raised to 789 or 820 mg.kg-1, respectively. The LD50 of NiCl2 was 39 mg.kg-1 in rat. If CBMIDA was injected i.m. 0.5 g.kg-1 after i.p. NiCl2, the LD50 was 332 mg.kg-1. CBMIDA 1.5 g.kg-1 i.m. after i.v. 63NiCl2, decreased the contents of 63Ni in blood and lung of mice vs control mice at 24 h. The contents of 63Ni in brain, heart, spleen, and kidney were similar to those of the control mice. The content of 63Ni in bone was more than the control. The excretions of 63Ni through urine and feces were not increased by CBMIDA at 24 h. The whole-body autoradiography showed that the radioactivity was highly localized in the kidney, lung, and Harder's gland. There was a moderate level of 63Ni in the liver, bone, skin, and blood. A pronounced accumulation occurred in the bone. There was a marked reduction of 63Ni in the lung, skin, liver, and blood after i.p. CBMIDA.

CONCLUSION

The CBMIDA markedly raised the survival rate of nickel-poisoned mice and rats, and decreased 63Ni levels in lung and blood.

[Regulation of traditional Chinese medicine formulae bailong on cAMP-PKA and DAG-PKC signal pathways of human gastric cancer cells]

OBJECTIVE

To evaluate the effects of traditional Chinese medicine formulae (Bailong) on cAMP/PKA and diacylaglycerol (DAG) protein kinase (PKC) pathways of the MGc80-3 cells.

METHODS

cAMP level, DAG content and activities of PKA and PKC were measured in different groups: (1) control, (2) 1.8 mg/ml Bailong, (3) 1.8 mg/ml Bailong +20 ug/ml PKA inhibitor, (4) 5 mumol/L PKC inhibitor.

RESULTS

When MGc80-3 cells were in treatment with Bailong for 3 hours, cAMP level and PKA activity were 11.27%, and 19.7% higher than that of the control, while DAG content and PKC activity were 47.0% and 64.2% lower than that of the control; When PKC pathway was blocked by PKC inhibitor GF-109203X, cAMP level and PKA activity were increased by 78.8% and 33.5% as against that of the control, while the DAG content and PKC activity were decreased by 40. 3% and 56.3% respectively. When MGc80-3cells were treated with Bailong, and at the same time, blocked PKA pathways by PKA inhibitor, cAMP level and PKA activity were decreased by 46.0% and 28.9%, on the other hand, DAG content and PKC activity were increased by 50.7% and 51.6% as against that of the Bailong group.

CONCLUSIONS

(1) There was relationship of causes and result between differentiation of MGc80-3 cells and the signal pathways. (2) Results of this study were similar to that of hexamethylenebisacetamide (HMBA). It is shown that the two signal systems are the foundation of regulative effects of Chinese medicine formulae Bailong or HMBA on proliferation and differentiation in MGc80-3 cells.

Quantitative changes in cytoskeletal and nuclear actins during cellular transformation

Actin, a highly conserved protein comprising cell stress fibers and other cellular structures, is found in both the cytoplasm and nucleus of cells and responds to both epigenetic signals and altered gene expression occurring during tumorigenesis. We have previously shown that changes in the cytoplasmic F- and G-actin ratios reflect bladder cancer risk. To determine whether nuclear actin is also altered and how nuclear and cytoplasmic actin alterations are interrelated in transformation, an in vitro model of carcinogen-induced transformation consisting of 2 human uroepithelial cell lines immortalized by infection with SV-40 was studied. One line, HUC-PC, is tumorigenic in nude mice after incubation with the carcinogen 4-ABP, the other, HUC-BC, is not. Cytoplasmic and nuclear F- and G-actin were determined by QFIA on individual cells using fluorochrome-labeled phallicidin and DNase, I, respectively. Before exposure to 4-ABP, the PC cells had lower cytoplasmic F-actin content, higher cytoplasmic G-actin content, but similar levels of nuclear G- and F-actin in comparison to the BC cells. After incubation with 4-ABP, F-actin decreased and G-actin increased in both cytoplasm and nuclei of PC cells and cytoplasmic F-actin fibers were lost, but only cytoplasmic actin was altered in the BC cells. Northern blot analysis showed the expression of the beta-actin gene was only approximately 20% lower in 4-ABP-treated PC cells than in untreated controls, indicating the cellular change in actin was attributed to a shift between F- and G-actin proteins rather than to net actin synthesis.

[Co-regulative effect of PKA-RII and PKC-alpha kinase subspecies on expression of c-myc and c-H-ras in human gastric cancer cells (MGC 80-3)]

Based on preceding experiment, we further studied the co-regulative effects of PKA-R II and PKC-alpha on expression of oncogenes in human gastric cell line MGC 80-3. The c-myc and c-H-ras expression were suppressed in MGC 80-3 cells during HMBA-induced differentiation. At the same time, PKA-R II showed nuclear translocation from cytoplasm, whereas the expression of PKC-alpha shifted from nucleus to cytoplasm. PKA inhibitor (Sigma) was added to block cAMP-PKA pathway when cell differentiation were induced by HMBA. The PKA-R II was still located in cytoplasm but expression of PKC-alpha translocated again into nucleus. Meanwhile, the c-myc and c-H-ras again expressed. This suggested that the changing regulation of oncogene expression were closely related to signalling from nuclear translocation of kinase subspecies. It thus shows the co-regulation effects of two signal system on oncogenes expression.

Cardiac and regional hemodynamic interactions between halothane and nitric oxide synthase activity in dogs

BACKGROUND

In vitro, halothane appears to affect the role played by nitric oxide in the regulation of vascular tone and cardiac function. In vivo, the results of the interactions between halothane and the nitric oxide pathway remain controversial. The authors investigated the effects of halothane on the cardiac and regional hemodynamic properties of N-methyl-L-arginine (NMA), a specific nitric oxide synthase inhibitor, in dogs.

METHODS

Twenty-five dogs were chronically instrumented. Aortic pressure, the first derivative of left ventricular pressure, cardiac output, heart rate, and carotid, coronary, mesenteric, hepatic, portal and renal blood flows were continuously recorded. N-methyl-L-arginine was infused intravenously at 20 mg/kg over 1 min in awake dogs (n = 11) and in 1.2% halothane-anesthetized dogs (n = 10). As a control group, the remaining four dogs were studied awake and during 1.2% halothane for 2 h in the absence of NMA.

RESULTS

In awake dogs, NMA produced a sustained pressor response (34%) and systemic vasoconstriction (40%) associated with a decrease in cardiac output (16%). Regional circulation changes included an immediate and transient increase in carotid (43%) and coronary (237%) blood flows and a subsequent decrease in carotid blood flow (25%). Hepatic and mesenteric blood flows also decreased, by 43% and 16%, respectively. Except for the coronary circulation, regional vascular resistance increased significantly. Halothane did not affect the pressor response to NMA but did blunt the cardiac output changes. Consequently, the systemic vasoconstriction after nitric oxide synthase inhibition was of shorter duration and of lesser magnitude during halothane anesthesia. Halothane also blunted the carotid, mesenteric, and renal vasoconstriction induced by NMA. Finally, in 1.2% halothane-anesthetized dogs, NMA induced a coronary vasoconstriction.

CONCLUSIONS

Halothane minimally interferes with the systemic and regional hemodynamic consequences of nitric oxide synthase blockade. The nature and magnitude of the interaction depend on the territory in which they occur.

The public health impact of Lyme disease in Maryland

The purpose of this study was to estimate the health burden imposed by Lyme disease (LD) in Maryland during 1992 and 1993. A cross-sectional 1-in-15 survey of physicians (total, 1200) in Maryland was conducted to estimate the incidence of diagnosed LD, presumptive cases of LD, patients with tick bites, and diagnostic tests ordered for LD. Results show that LD is underreported by 10- to 12-fold in Maryland, that 80% of cases are managed by primary care physicians, and that there is discordance between the actual clinical treatment of patients and the recommended approach. In addition, the much greater numbers of patients treated for presumptive LD, seen and given prophylaxis for tick bites, and having diagnostic tests indicate that real and perceived LD is a far greater public health problem and uses more medical resources than official surveillance data suggest.

p53 mutations in esophageal tumors from high-incidence areas of China

Carcinomas of the upper digestive tract (squamous-cell carcinoma of the esophagus, adenocarcinoma of the cardia) from 24 patients residing in Linxian (China) and near-by high-incidence areas were analyzed for mutations in exons 5-8 of the p53 tumor-suppressor gene. Mutations were identified by polymerase chain reaction amplification and direct sequencing in 50% of the specimens. Eleven tumors harbored a single base-pair substitution leading to either an amino-acid substitution (8 tumors) or a chain-termination signal (3 tumors), and one tumor revealed a 15-bp deletion in exon 7 with a silent base substitution adjacent to the deletion site. Mutations occurred in all 4 exons examined, with a preponderance in exon 5. Of the 6 mutations identified among the 14 adenocarcinomas examined, 3 were G to T transversions, a mutation that has thus far been absent from reported mutations in Barrett's esophageal adenocarcinomas and dysplasias from patients residing in Europe and North America.

[Alterations of oncogenes in human fetal esophageal epithelium induced by N-methylbenzylnitrosamine (NMBzA)]

Epidemiological investigation showed that N-methylbenzylnitrosamine (NMBzA) has been associated with increased incidence of esophageal cancer (EC) in Linxian county, a high incidence area. In present study, our results indicate that NMBzA can induce amplification and over-expression of EGFr gene in human fetal esophageal epithelium (HFE) treated with NMBzA for 24 hours as shown by southern blot assay and immunohistochemistry. The papillary hyperplasia was induced in HFEs that cultured with NMBzA for 1 to 3 weeks. Amplification of c-myc and int-2 gene in HFEs treated by NMBzA for 1 week and 3 weeks was found, respectively. Deletions of p53 and Rb gene were found in human fetal esophageal carcinomas induced by NMBzA. Overexpression of p53 protein in human fetal esophageal carcinomas detected by immunohistochemical methods indicates that p53 gene mutation(s) may be occured. The HFE explants treated in vitro with NMBzA for 3 weeks were inoculated subcutanously into balb/c nude mice. No tumor was found in 5 months after inoculation, suggesting that only changes of oncogene(s) are insufficient to induce full transformation. Other genetic alterations (such as functional inactivation of Rb or/and p53 tumor suppressor genes) may be necessary in the further progression of malignant lesions.

[Effect of dimercaptosuccinic acid per os on distribution and excretion of 210Pb and 203Hg in mice]

Sodium dimercaptosuccinate (Na-DMS) ip 1 g.kg-1, dimercaptosuccinic acid (DMSA) ig 1 g.kg-1, DMSA ig 1 g.kg-1 with NaHCO3 or Na-citrate ig 3 g.kg-1 was given to mice, separately. It enhanced the excretion of 210Pb in urine about 3.4, 3.8, 3.6, and 2.3 times vs control, respectively within 24 h. It enhanced the excretion of 203Hg in urine about 2.4, 2.3, 3.3, and 2.7 times, respectively within 24 h. Fecal excretion was not significantly elevated vs control. Tissue radioactivities showed a remarkable decrease in the levels of 210Pb and 203Hg in most organs, but DMSA increase the 210Pb content in kidney. The therapeutic effect of ig DMSA was similar to that of ip sodium dimercaptosuccinate.

[Whole-body autoradiographic localization of catecholamic acid in mice]

Catecholamic acid [catechol-3,6-bis-(methyleneimino diacetic acid)] is a chelating agent synthesized in our institute. Whole-body autoradiographic study was carried out to determine the distribution of [14C]catecholamic acid in 5 adult male mice. Each mouse was injected i.v. 370 kBq. After various times the mice, under ether anesthesia, were immersed in a mixture of dry ice and hexane. Whole-body sections were made at -20 C, 20 microns in thickness. Results showed: (1) At 5 min, higher radioactivities appeared in blood, kidneys, gastrointestinal mucosa, bone, skin, and hair; moderate concentrations in liver, lungs, spleen, and salivary glands. (2) During 20 min and 3 h, the radioactivities decreased (gradually) in all tissues except the bone. (3) Intense radioactivity persisted in the bone, while only traces remained in the kidneys and intestinal mucosa throughout the 24 h period of observation.

[Effects of dimercaptosuccinic acid per os on copper excretion in rat]

After dimercaptosuccinic acid (DMSA) was given intragastrically by gavage (ig) 0, 250, or 500 mg.kg-1 following in CuSO4 30 mg.kg-1 daily x 3 d in rats, the Cu contents of serum increased markedly within 1-12 h. When ig DMSA daily x 3 d, the excretion of Cu in urine per 24 h in the treated group was greatly promoted vs the control (P < 0.01), that in the 250 or 500 mg.kg-1 group were enhanced 2.4-3.8 and 5.8-7.8 times, respectively. That the excretion of Cu was increased in bile but not in feces suggested the plausible existence an enterohepatic circulation.

[Multiple gene alterations in human esophageal squamous cell carcinoma]

In 45 human esophageal squamous cell carcinomas, 29 showed alterations of EGFr, c-myc, int-2, Rb and p53 gene by Southern blot hybridization, a frequency of 15.6%, 31.1%, 35.6%, 22.2%, 6.7%, respectively. Among these cases, 16 cases showed two or multiple gene changes, and most of them were of II-III stage. The results suggest that gene alterations may be related to pathological stages of the disease. The poorer the differentiation of the tumor, the more gene changes were accumulated. We did not find association between the presence of metastasis in lymph nodes and the gene alterations.

[Study on the relationship between two second-messenger pathways on the regulation of proliferation and differentiation in MGc 80-3 cells]

By using an inducer of differentiation (HMBA) and blockers of signal pathways, the relationship between two second-messenger pathways (DG-PKC, cAMP-PKA) in inducer-mediated MGc80-3 cell differentiation was studied. Cells were treated with HMBA for 24 h, levels of DG decreased by 64.7%, activity of PKC decreased by 28.7%, while levels of cAMP and rate of it's protein binding increased by 62% and 32.6% respectively (after treated for 48 h, the result was more remarkable). PKA-R II distributed in nuclei. H7 (PKC inhibitor) was used to substitute for HMBA to block the DG-PKC pathway. After treatment for 24 h, the levels of DG and activity of PCK both decreased, while the levels of cAMP increased 1.04 times. On the contrary, PKA inhibitor was added while HMBA was used to induce cell differentiation, cAMP-PKA pathway was blocked, levels of cAMP and rate of it's protein binding decreased. But levels of DG and activity of PKC both increased to the levels of control cells. At this time, PKA-R II distributed only in cytoplasm. These results suggest that harmonious relations of the positive and negative regulation of cAMP-PKA and DG-PKC systems in cells during the proliferation and differentiation of cells. It also showed that positive regulation of PI system may play a leading role in MGc80-3 cells. It let to normal regulation of two signal pathway out of control to remain malignant phenotype of these cells.

Characterization of the ntrBC genes of Azospirillum brasilense Sp7: their involvement in the regulation of nitrogenase synthesis and activity

A 7.1 kb EcoRI fragment from Azospirillum brasilense, that hybridized with a probe carrying the ntrBC genes from Bradyrhizobium japonicum, was cloned. The nucleotide sequence of a 3.8 kb subfragment was established. This led to the identification of two open reading frames, encoding polypeptides of 401 and 481 amino acids, that were similar to NtrB and NtrC, respectively. A broad host range plasmid containing the putative Azospirillum ntrC gene was shown to restore nitrogen fixation under free-living conditions to a ntrC-Tn5 mutant of Azorhizobium caulinodans. Several Tn5 insertion mutants were isolated in the ntrBC coding region in A brasilense. These mutants were prototrophic and Nif+. However, their nitrogenase activity was slightly lower than in the wild type and they were unable to grow on nitrate as sole nitrogen source. Under microaerobiosis and in the absence of ammonia, a nifA-lacZ fusion was expressed in the mutants at about 60% of the level in the wild type. In the presence of ammonia, the fusion was similarly expressed (60% of the maximum) both in the wild type and mutants. Addition of ammonia to a nitrogen-fixing culture of ntrBC mutants did not abolish nitrogenase activity, in contrast with the wild type. It thus appears that in Azospirillum the ntrBC genes are not essential for nitrogen fixation, although NtrC controls nifA expression to some extent. They are, however, required for the switch-off of nitrogenase activity.

Regulation of nitrogen fixation inAzospirillum brasilenseSp7: Involvement ofnifA, glnAandglnBgene products

The expression of nifA-, niH- and nifB-lacZ fusions was examined in different mutants of Azospirillum brasilense. Mutations in nifA, glnA and glnB severely impaired the expression of nifH- and nifB-lacZ fusions. By contrast, a nifA-lacZ fusion was not affected in a nifA or a glnB background and was only partially impaired in glnA mutants. It is proposed that in A. brasilense, the PII protein and glutamine synthetase are involved in a post-translational modification of NifA.

A study on a family with high incidence of leukemia

A family with a high incidence of leukemia was investigated and followed up for 10 years. Up to now, 7 of 48 members in this family had acute nonlymphocytic leukemia. Chromosomal aberration was found in 3 healthy members, 2 of whom were found to have 47, XX, +5, -8, +Mar, del (7) (q22-qter) and 45, XO, -Y chromosomes and developed this disease 5 and 7 years later respectively. Pedigree analysis suggested that the hereditary defect in the family should rest on the maternal lineage. It is considered that hereditary factors play an important part in the pathogenesis of leukemia in the family.

The ouabain-dependent Na(+)-K+ pump and the brain renin-angiotensin system

The present study investigated the role of ouabain-dependent inhibition of the Na(+)-K+ pump and stimulation of the brain renin-angiotensin system by looking at 1) the short-term and long-term effects of ouabain on arterial blood pressure, and 2) the acute and chronic effects of angiotensin II (ANG II) intraventricularly (i.c.v.) on the release of an endogenous inhibitor of the Na(+)-K+ pump. Ouabain infused subcutaneously in a dose of 1.5 mg.kg-1. 24 h-1 for 7 days did not affect arterial blood pressure in rats, whereas increases in both blood pressure and weight were observed in rats infused with ouabain at the same dose for a 4-week period. Plasma supernate obtained from pentobarbital-anesthetized dogs acutely treated with ANG II (1 microgram i.c.v. every 30 min for 2 h) induced a 44% decrease in the ouabain-sensitive 86Rb uptake by the rat tail artery which was prevented by pretreatment with saralasin i.c.v. Plasma supernate obtained from dogs that were infused for 4 days with ANG II (20 ng/min i.c.v.) and received saline as the drinking fluid also reduced by 34% the ouabain-sensitive 86Rb uptake by the rat tail artery. The present study provides evidence that chronic inhibition of the Na(+)-K+ pump for 4 weeks leads to the development of hypertension and that the release of an endogenous inhibitor of the Na(+)-K+ pump is implicated in the hypertension resulting from chronic stimulation of the brain angiotensin-system and an increase in sodium chloride intake.

Identification of a nifA-like regulatory gene of Azospirillum brasilense Sp7 expressed under conditions of nitrogen fixation and in the presence of air and ammonia

A gene bank of Azospirillum lipoferum Br17 constructed in the vector lambda GEM11 was screened with a Bradyrhizobium japonicum nifA gene probe. A 7.3 kb EcoRI fragment carrying a nifA-like gene was thereby isolated and subsequently used to screen a gene bank of Azospirillum brasilense Sp7 constructed in pUC18. Two EcoRI fragments of 5.6 kb and 3.6 kb covering the nifA-homology region were found. Mutants with Nif- phenotype were obtained by site-directed Tn5 mutagenesis of the 5.6 kb fragment and subsequent recombination into the A. brasilense Sp7 genome. The mutations were clustered into two loci located at each extremity of the fragment. One of these loci corresponded to nifA and the other to nifB. The nucleotide sequence of nifA of A. brasilense Sp7 was determined. Comparison of the deduced amino acid sequences of NifA of A. brasilense Sp7 and NifA of B. japonicum, Rhizobium leguminosarum biovar trifolii and Klebsiella pneumoniae confirmed that it was a nifA-like gene. Construction of a nifA-lacZ fusion and mapping of the RNA transcriptional start site showed that the nifA-like gene was expressed from an unidentified promoter, under conditions of nitrogen fixation and in the presence of oxygen and ammonia.

[Scavenging effects of dimercaptosuccinic acid per os on nickel in mice and rats]

In mice and rats given iv or im 63NiCl2 148-370 kBq, radioactivity was present in highest concentrations in kidney, lung, and liver. After given ig dimercaptosuccinic acid (DMSA) 1 g.kg-1, radioactivity decreased remarkably in kidney, lung, and blood. The excretion of 63Ni via urine and feces within 24 h, respectively 13.0 +/- 2.4% and 0.6 +/- 0.4%, was similar to that in the control group in mice. But radioactivity increased markedly in bone. The Ni content of bone decreased on d 7. In rats given im 63NiCl2 370 kBq, two different nickel complex peaks appeared in the gel chromatograms of serum, kidney, and lung. DMSA reduced the contents of protein-bound Ni in serum, kidney, and lung. The results showed that DMSA detoxified the Ni by forming a low toxicity Ni-DMSA complex to redistribute in the body.

[Expression of c-myc and HER-1 genes in the development of human esophageal cancer]

To understand the possible role of oncogenes in the development of human esophageal cancer, the expression of c-myc and HER-1 genes was studied by in situ hybridization. The results showed that: (a) The c-myc and HER-1 protooncogenes were transcriptionally activated (b) Activation of c-myc gene was observed in hyperplastic cells and carcinoma cells. (c) The degree of pathological changes of the esophageal epithelium was related to the level of c-myc transcription, the highest level of c-myc expression was seen in invasive carcinoma cells. (d) Expression of HER-1 gene in carcinoma cells is higher than that in normal and adjacent non-tumor cells, but its frequency is lower than that of c-myc gene.

[Whole body autoradiographic localization of dimercaptosuccinic acid per os in mice]

Dimercapto [14C]succinic acid ([14C]DMSA) was given to male mice by ig 233 kBq. The mice were sacrificed by immersion in dry ice/hexane at 1, 3, 9 and 24 h. The distribution and concentration of [14C]DMSA were observed and analysed by whole-body autoradiograph. Higher concentration appeared in oral cavity, esophagus, gastrointestinal contents, liver, kidney and urine at 1 or 3 h. A moderate concentration was seen in blood, bone and skin. A remarkable reduction of radioactivity was found in liver at 9 h, but GI contents, Harderian gland, kidney and urine retained intense distribution. The results indicated that DMSA absorbed rapidly per os and was eliminated by kidney within 24 h. No tissue had a pronounced retention of the [14C]DMSA.

Antidotal effects of dimercaptosuccinic acid

Dimercaptosuccinic acid (DMS), HOOC-CH(SH)-CH(SH)-COOH, was first developed in China as an effective antidote for poisoning from many heavy metals, such as Pb, Hg, As, Cd, Sb, Tl, Au, Zn, Ni, Pt, Ag, Co and Sn. DMS increases the excretion of Ce, Pm, Sr and Po from the body. Hundreds of patients suffering from hepatolenticular degeneration (Wilson's disease) have been treated successfully with DMS. Recently, DMS was found to be effective also in treating certain non-metallic intoxications, like some of the new non-phosphate pesticides and mushroom poisonings.

The antisense c-Ha-ras oligodeoxynucleotides inhibit the proliferation of the gastrocarcinoma-DNA-transformed rat 3-3 cells and reduce the p21 expression of the cells

The Rat 3-3 is a secondary transformant of the rat fibroblast cell line (Rat-1) transfected with total DNA of a gastrocarcinoma cell line BGC-823. The cells over-express the c-Ha-ras oncogene which contains point mutation at the 12th codon. In order to determine how the activated c-Ha-ras oncogene expression governs the cell's transformation, two pentadecadeoxy-nucleotides AS-1 and AS-2 were synthesized. AS-1 was complementary to the single strand of the first three codons and the upstream sequence close to the ribosome binding site of c-Ha-ras mRNA. AS-2 was complementary to the 3' end of the first intron and the 5' end of the second exon of c-Ha-ras unripe RNA enclosed in the nucleus. The oligonucleotides could block either the translation of c-Ha-ras mRNA or the splicing of c-Ha-ras unripe RNA, thus inhibiting the expression of the activated c-Ha-ras oncogene and the proliferation of the transformed cells Rat 3-3. The inhibitory effect increased with a growing concentration of the antisense oligodeoxynucleotide (from 4-10 mumol/L) and reached its peak at 12 h after Rat 3-3 was treated with AS-1 and AS-2. This effect became weaker afterwards. The p21 level, product of c-Ha-ras, in the Rat 3-3, was examined by ELISA method. The result shows that the amount of p21 in the growth-inhibited cells is about 30% of that of the control cells.

Effect of gender in centrally induced angiotensin II hypertension in dogs

This study was designed to investigate the relation between gender, an endogenous inhibitor of the Na+-K+ pump, and volume-dependent hypertension induced by stimulation of the brain renin-angiotensin system and increased salt intake. Angiotensin II (20 ng/min i.c.v.) was infused for 4 weeks in five dogs of each sex with saline as the drinking fluid. In male dogs, angiotensin II induced parallel pressor (30%) and dipsogenic responses (70%), whereas no hypertension and no increase in fluid intake were observed in females. In contrast, the activity of the Na+-K+ pump as assessed by 86Rb uptake was independent of gender. Our data provide novel evidence that gender plays a determining role in the physiological properties of centrally administered angiotensin II.