Contribution of Matrix Metalloproteinase-2 Genotypes to Taiwan Pterygium Risk

BACKGROUND/AIM

In the literature, the studies about the role of matrix metalloproteinase-2 (MMP-2) in pterygium diagnosis are mainly based on its protein expression. The role of MMP-2 variants has never been examined. The aim of this study was to examine the association of MMP-2 genotypes with pterygium risk.

MATERIALS AND METHODS

MMP-2 rs243865 and rs2285053 were genotyped in 140 pterygium cases and 280 non-pterygium controls by typical polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) genotyping technology.

RESULTS

The genotypic frequency of MMP-2 rs243865 CC, CT and TT were 86.4%, 12.9% and 0.7% in the pterygium group and 81.1%, 17.1% and 1.8% in the non-pterygium group (p for trend=0.3389). The variant CT and TT carriers had a 0.70- and 0.38-fold pterygium risk (95%CI=0.39-1.26 and 0.04-3.25, p=0.2982 and 0.6686, respectively). As for MMP-2 rs2285053, the genotypic frequency of CC, CT and TT were 67.1%, 28.6% and 4.3% in the pterygium group, non-significantly different from those in non-pterygium group (p for trend=0.7081). The CT and TT carriers had a 0.88- and 0.71-fold pterygium risk (95%CI=0.56-1.38 and 0.27-1.88, p=0.6612 and 0.6456, respectively). The allelic analysis results showed that MMP-2 rs243865 variant T allele was not associated with pterygium risk (7.1% versus 10.4%, OR=0.67, 95%CI=0.39-1.13, p=0.1649). As for MMP-2 rs2285053, the T allele was not associated with pterygium risk either (18.6% versus 21.1%, OR=0.85, 95%CI=0.59-1.23, p=0.4136).

CONCLUSION

The genotypes at MMP-2 rs243865 or rs2285053 played minor role in determining individual susceptibility for pterygium among Taiwanese.

Association of Matrix Metalloproteinase-7 Genotypes With Prostate Cancer Risk

BACKGROUND/AIM

Prostate cancer is one of the most commonly diagnosed malignancies among males worldwide. It has been shown that MMP-7 gene is closely correlated with prostate carcinogenesis. However, the role of the MMP-7 genotypes has been seldom examined among prostate cancer patients. Therefore, the purpose of the study was to evaluate the contribution of MMP-7 promoter genotypes A-181G (rs11568818) and C-153T (rs11568819) to prostate cancer risk in Taiwan.

MATERIALS AND METHODS

Two hundred and eighteen prostate cancer patients and 436 sex- and age-matched healthy controls were genotyped for MMP-7 rs11568818 and rs11568819 by polymerase chain reaction-restriction fragment length polymorphism and direct sequencing methodologies.

RESULTS

The percentages of wild-type AA, and variant AG and GG genotypes on MMP-7 rs11568818 were 85.3, 13.5, and 1.2% among the prostate cancer cases and 87.6, 10.1, and 2.3% among the healthy controls, respectively (p for trend=0.2557). Interestingly, no MMP-7 rs11568819 genotypes were identified among Taiwanese. The allelic frequency distribution also showed that the variant G allele of MMP-7 rs11568818 seemed not to be a determinant of prostate cancer risk (p=0.7977). There was no joint effect between the genotypes of MMP-7 rs11568818 and age and smoking status on prostate cancer risk.

CONCLUSION

rs11568818 and rs11568819 at MMP-7 promoter region, played no role in determining personal susceptibility to prostate cancer in Taiwan.

The Association of MMP7 Genotype With Pterygium

BACKGROUND/AIM

In literature, few studies have examined the diagnostic or prognostic potential of matrix metalloproteinases (MMP) in pterygium, whose formation and progression are closely related to imbalance in the extracellular microenvironment. In this study, we investigated the contribution of MMP7 promoter (A-181G and C-153T) polymorphic genotypes to pterygium risk.

MATERIALS AND METHODS

A total of 134 cases and 268 controls were collected and their MMP7 genotypes at A-181G and C-153T were examined by polymerase chain reaction-restriction fragment length polymorphism methodology.

RESULTS

The AA, AG and GG genotypes at MMP7 promoter A-181G were non-significantly differentially distributed between the two groups at 85.8, 11.2 and 3.0%, respectively, in pterygium cases and 88.4, 9.7 and 1.9% in controls, respectively (p for trend=0.6822). There was no polymorphic genotype for MMP7 C-153T among our Taiwanese cohort.

CONCLUSION

A-181G and C-153T genotypes at MMP7 do not have a direct role in determining Taiwanese susceptibility to pterygium.

Association of Matrix Metalloproteinase-7 Genotypes with the Risk of Bladder Cancer

BACKGROUND/AIM

The breakage of matrix metalloproteinases (MMPs) has been reported to be one of the mechanisms required for tumor invasion, and the expression of MMP-7 in serum is correlated with poor prognosis of urinary bladder cancer patients. However, the role of the MMP-7 genotypes has been seldom examined among bladder cancer patients. Therefore, this study aimed at examining the promoter polymorphic MMP-7 genotypes A-181G and C-153T among Taiwanese bladder cancer patients and evaluate the contribution of the genotypic variants of MMP-7 to bladder cancer risk in Taiwan.

MATERIALS AND METHODS

Three hundred and seventy-five bladder cancer patients and the same number of gender- and age-matched healthy controls were genotyped for A-181G and C-153T in the promoter of MMP-7 via polymerase chain reaction-restriction fragment length polymorphism methodology.

RESULTS

The frequencies of AA, AG and GG at A-181G of the promoter of MMP-7 were 89.1, 8.8 and 2.1% in the bladder cancer patient group and 87.5, 10.9 and 1.6% in the matched healthy control group, respectively (p for trend=0.5475). There was no polymorphic genotype for MMP-7 C-153T among the Taiwanese population. The comparisons in allelic frequency distribution also support the findings that the G allele may not be the determinant allele for bladder cancer in Taiwan. In addition, the results showed that there is no significant association of the bladder risk with the MMP-7 A-181G genotype, even after adjustment for the possible confounding factors. Furthermore, there is no interaction of the genotypes of MMP-7 with age, gender, smoking and alcohol consumption on bladder cancer risk.

CONCLUSION

The results of this study suggest that the two MMP-7 polymorphisms, - A-181G and C-153T, do not play a major role in determining personal susceptibility to bladder cancer in Taiwan.

The Association of MMP-8 Genotypes with Pterygium

BACKGROUND/AIM

Pterygium is composed of proliferating fibrovascular tissue, and its formation and progression are closely related to the homeostasis of the extracellular microenvironment. However, few studies have examined the contribution of matrix metalloproteinases (MMP) to either diagnostic or prognostic potential in pterygium. In this study, we investigated the contribution of a polymorphism in the promoter region of MMP-8 (-799C/T) and two non-synonymous polymorphisms (Val436Ala and Lys460Thr) to pterygium.

MATERIALS AND METHODS

In this study, 134 patients with pterygium and 268 non-cancer controls patients were collected and the MMP-8 -799C/T, Val436Ala and Lys460Thr polymorphic genotypes of each subject were examined by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP).

RESULTS

The results showed that the three polymorphisms investigated were not significantly associated with risk of pterygium. In addition, the stratified analysis showed that there was no interaction between MMP-8 genotype with age or gender on pterygium risk determination.

CONCLUSION

Polymorphisms at MMP-8 -799C/T, Val436Ala and Lys460Thr may not mainly contribute to determining personal susceptibility to pterygium in the Taiwanese examined.

The Association of Matrix Metalloproteinase-1 Promoter Polymorphisms with Prostate Cancer in Taiwanese Patients

BACKGROUND/AIM

The family of matrix metalloproteinases (MMPs) is responsible for the maintenance of extracellular matrix component homeostasis and the association of MMP-1 genetic polymorphisms with personal susceptibility to prostate cancer has only been investigated in Turkish and Japan populations and never in Taiwan. In the current study, we aimed to examine the contribution of a polymorphism in the promoter region of MMP-1 to Taiwan prostate cancer.

MATERIALS AND METHODS

The MMP-1 rs1799705 polymorphic genotypes were genotyped among 218 prostate cancer patients and 436 healthy controls by the typical polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) methodology.

RESULTS

The percentages of 2G/2G, 1G/2G, and 1G/1G for MMP-1 -1607 genotypes were 36.2, 40.4 and 23.4% in the prostate cancer group and 33.7, 44.3, and 22.0% in the healthy control group (p trend=0.6362), respectively. The odds ratios (ORs) after adjusting for age and smoking status for those carrying 1G/2G and 1G/1G genotypes at MMP-1 -1607 were 0.84 (95%CI=0.55-1.21, p=0.3862) and 0.94 (95%CI=0.67-1.53, p=0.9586), respectively, compared to those carrying the wild-type 2G/2G genotype. Supporting these findings, the adjusted OR for those carrying the 1G allele at MMP-1 -1607 was 1.03 (95%CI=0.71-1.45, p=0.6910), compared to those carrying the wild-type 2G allele.

CONCLUSION

Our findings suggest that the polymorphic genotypes at MMP-1 promoter -1607 may play a major role in determining personal cancer susceptibility for prostate cancer in Taiwan.

The Contribution of MMP-7 Promoter Polymorphisms in Renal Cell Carcinoma

BACKGROUND/AIM

Mounting evidence has suggested that polymorphisms in the promoters of matrix metalloproteinase (MMP) genes are associated with the risk of many types of cancer, but no study has ever explored these polymorphisms as biomarkers for renal cell cancer (RCC). Recently, it was suggested that serum MMP-7 levels have both diagnostic and prognostic potential for RCC. In this study, we focused on the contribution of two functional polymorphisms in the promoter region of MMP-7 (A-181G and C-153T) to RCC.

MATERIALS AND METHODS

These two polymorphisms were genotyped in 92 patients with RCC and 580 controls by PRC-RFLP analysis.

RESULTS

The results showed that there is no significant association of the RCC risk with the MMP-7 A-181G genotype, even after adjusted for the possible confounding factors. The MMP-7 C-153T polymorphism was not identified among the subjects investigated.

CONCLUSION

Our findings suggest that the two MMP-7 polymorphisms A-181G and C-153T do not play a major role in determining personal susceptibility to RCC in Taiwan.

Physiochemical properties of rice starch for production of vermicelli with premium quality

Rice vermicelli is a main food consumed in China and Southeast Asia. Quality of rice vermicelli varies with rice cultivars. Parameters including amylose content, amylopectin distribution, thermal and pasting characteristics, gel texture and starch granules of three rice cultivars "Zhongjiazao 17", "Xiangzaoxian 24" and "Thai Jasmine Rice", were studied for their impacts on vermicelli quality. Results showed significant differences for the measurements of the quality traits and indicated that a favorable quality of vermicelli was not determined by any single factor instead of a combination of multi-parameters. A vermicelli with a favorable quality could be produced from a rice variety with a high apparent amylose content (>25%), a protein content of 11%, an intermediate gelatinization temperature and gel consistency, and a gel hardness (~3 N for a Rapid Viscosity Analyzer pasting) and moderate retrogradation capacity (a setback viscosity of 30-100 RVU).

Association of Enhancer of Zeste 2 (EZH2) Genotypes with Bladder Cancer Risk in Taiwan

AIM

Bladder cancer is the sixth most common cancer worldwide and its incidence is particularly high in many developed regions including southwestern Taiwan. However, the genetic contribution to the etiology of bladder cancer is not well-understood. The aim of this study was to evaluate the association of the enhancer of zeste homolog 2 (EZH2) genotypes with Taiwan bladder cancer risk.

MATERIALS AND METHODS

Three polymorphic variants of EZH2 were analyzed regarding their association with bladder cancer risk, and three hundred and seventy-five patients with bladder cancer and same number of age- and gender-matched healthy controls recruited were genotyped by the PCR-RFLP method.

RESULTS

Among the three polymorphic sites examined, the genotypes of EZH2 rs887569 (C to T), but not rs41277434 (A to C) or rs3757441 (T to C), were positively associated with bladder cancer risk (p for trend =0.0146). Individuals with the EZH2 rs887569 TT genotypes were associated with decreased cancer risk than those with wild-type CC genotype. The stratified analyses showed that EZH2 rs887569 TT genotypes had protective effects on non-smokers but obviously not on smokers.

CONCLUSION

Our findings provide evidence that the T allele of EZH2 rs887569 may be associated with the lower risk of bladder cancer development, especially among non-smokers.

Characterization and gene cloning of the rice (Oryza sativa L.) dwarf and narrow-leaf mutant dnl3

The dwarf and narrow-leaf rice (Oryza sativa L.) mutant dnl3 was isolated from the Japonica cultivar Zhonghua 11 (wild-type). dnl3 exhibited pleiotropic developmental defects. The narrow-leaf phenotype resulted from a marked reduction in the number of vascular bundles, while the dwarf stature was caused by the formation of foreshortened internodes and a reduced number of parenchyma cells. The suggestion that cell division is impaired in the mutant was consistent with the transcriptional behavior of various genes associated with cell division. The mutant was less responsive to exogenously supplied gibberellic acid than the wild-type, and profiling the transcription of genes involved in gibberellin synthesis and response revealed that a lesion in the mutant affected gibberellin signal transduction. The dnl3 phenotype was inherited as a single-dominant gene, mapping within a 19.1-kb region of chromosome 12, which was found to harbor three open reading frames. Resequencing the open reading frames revealed that the mutant carried an allele at one of the three genes that differed from the wild-type sequence by 2-bp deletions; this gene encoded a cellulose synthase-like D4 (CSLD4) protein. Therefore, OsCSLD4 is a candidate gene for DNL3. DNL3 was expressed in all of the rice organs tested at the heading stage, particularly in the leaves, roots, and culms. These results suggest that DNL3 plays important roles in rice leaf morphogenesis and vegetative development.

Baicalin Scavenged Reactive Oxygen Species and Protected Human Keratinocytes Against UVB-induced Cytotoxicity

Ultraviolet B (UVB), with a wavelength of 280-320 nm, represents one of the most important environmental factors for skin disorders, including sunburn, hyperpigmentation, solar keratosis, solar elastosis and skin cancer. Therefore, protection against excessive UVA-induced damage is useful for prevention of sunburn and other human diseases. Baicalin, a major component of traditional Chinese medicine Scutellaria baicalensis, has been reported to possess antioxidant and cytostatic capacities. In this study, we examined whether baicalin is also capable of protecting human keratinocytes from UVB irradiation. The results showed that baicalin effectively scavenged reactive oxygen species (ROS) elevated within 4 h after UVB radiation and reversed the UVB-suppressed cell viability and UVB-induced apoptosis after 24 h. Our results demonstrated the utility of baicalin to complement the contributions of traditional Chinese medicine in UVB-induced damage to skin and suggested their potential application as pharmaceutical agents in long-term sun-shining injury prevention.

The Role of IL-10 Promoter Polymorphisms in Renal Cell Carcinoma

BACKGROUND/AIM

Renal cell carcinoma (RCC) accounts for approximately 3% of all cancer-related mortalities worldwide and the risk factors for the development of RCC have not yet been fully elucidated. Mounting proteomic evidence suggests that inflammatory process plays a role in RCC etiology and interleukin-10 (IL-10) is an important immunosuppressive cytokine. However, little is known on the contribution of IL-10 genotypes to RCC. This study aimed at evaluating the contribution of IL-10 promoter A-1082G (rs1800896), T-819C (rs3021097), A-592C (rs1800872) genetic polymorphisms to the risk of RCC in Taiwan.

MATERIALS AND METHODS

Associations of the three IL-10 polymorphic genotypes with the risk of RCC were examined among 92 RCC patients and 580 age- and gender-matched cancer-free controls by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) methodology.

RESULTS

The pilot results showed that the percentages of TT and TC for IL-10 T-819C genotypes were significantly higher in the RCC patient group than those in the healthy control group. The CC genotype carriers were of lower risk for RCC (odds ratio (OR)=0.33, 95% confidence interval (CI)=0.12-0.93, p=0.0369). There is no difference in the distribution of A-1082G or A-592C genotype between the RCC and control groups.

CONCLUSION

The CC genotype of IL-10 T-819C genotype may have a protective effect on RCC risk in Taiwan. Further investigation with larger sample size in addition to genotype-phenotype correlation and intracellular mechanisms are our future work.

Contribution of DNA Double-strand Break Repair Gene XRCC3 Genotypes to Triple-negative Breast Cancer Risk

AIM

The DNA-repair gene X-ray repair cross-complementing group 3 (XRCC3) is important in DNA double-strand break repair and plays a critical part in initiation of carcinogenesis. Triple-negative breast cancer (TNBC) is the most difficult breast cancer subtype with no existing gene-targeting drugs and little knowledge on its genetic etiology. This study aimed to investigate the contribution of the XRCC3 genotype to individual TNBC susceptibility.

MATERIALS AND METHODS

A total of 2,464 Taiwan citizens consisting of 1,232 breast cancer cases and 1,232 controls were enrolled in this case-control study, and genotyping of XRCC3 rs1799794, rs45603942, rs861530, rs3212057, rs1799796, rs861539 and rs28903081 were performed with polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). We also conducted risk-stratified sub-group analyses to determine the association between the genotype and age- and hormone-related characteristics of breast cancer sub-groups.

RESULTS

There was no significant difference between breast cancer and control groups in the distributions of the genotypic or allelic frequencies as for the XRCC3 rs1799794 (p=0.5195 and 0.9545), rs45603942 (p=0.3478 and 0.1449), rs861530 (p=0.4567 and 0.5081), rs3212057 (p=1.0000 and 1.0000), rs1799796 (p=0.8487 and 0.7315) and rs28903081 (p=1.0000 and 1.0000), respectively. However, the XRCC3 rs861539 TT genotype was more prevalent in patients with breast cancer [odds ratio (OR)=2.99, 95% confidence interval (CI)=1.62-5.55; p=0.0002], and especially among those who were younger than 55 years (OR=2.61, 95% CI=1.82-3.73; p=0.0001), with first menarche earlier than 12.2 years (OR=2.47, 95% CI=1.74-3.52; p=0.0001), with menopause at 49.0 years old or later (OR=2.53, 95% CI=1.76-3.62; p=0.0001), or with TNBC (OR=2.05, 95% CI=1.46-4.28; p=4.63*10(-4)).

CONCLUSION

XRCC3 rs861539 TT is a potential predictive marker for TNBC in Taiwanese women and investigations in other populations are warranted for further universal application in cancer detection and prediction.

Significant Association of Cyclo-oxygenase 2 Genotypes with Upper Tract Urothelial Cancer

AIM

Reliable biomarkers are in urgent need for diagnosis, outcome prediction and treatment-effect monitoring for upper tract urothelial carcinomas (UTUC). Although up-regulation of cyclo-oxygenase 2 (COX2) is found in stroma and tumor cells in more than half of the patients with UTUC investigated, the genomic contribution of COX2 to UTUC has not been studied. The study aimed to evaluate the association of six polymorphic genotypes of COX2 with UTUC within a Taiwanese population.

MATERIALS AND METHODS

A total of 218 patients with UTUC and 580 healthy controls were genotyped for six COX2 polymorphisms, namely A-1195G, G-765C, T+8473C, intron 1, intron 5 and intron 6, and examined for their association with UTUC risk.

RESULTS

The distribution of genotypes of COX2 G-765C and intron 5 were significantly different between patient and control groups (p=0.0001 and 0.0016, respectively), while others were not (p>0.05). The haplotype analysis showed that compared to the GG/TT haplotype of COX2 G-765C/intron 5, those carrying GG/AT variants have a significantly increased risk of UTUC (odds ratio=4.83, 95% confidence interval=1.79-13.06), while those carrying CG/TT variants have a decreased risk (odds ratio=0.26, 95% confidence interval=0.14-0.49).

CONCLUSION

Our results suggest that individual and combined COX2 G-765C/intron 5 genotypes play a role in controlling COX2 expression and UTUC development.

Fine mapping and characterization of a novel dwarf and narrow-leaf mutant dnl1 in rice

Plant height is one of the most important agronomic traits of rice (Oryza sativa). Dwarf mutants are ideal materials for research on the mechanisms of regulation of rice plant height. We examined a new dwarf and narrow-leaf mutant dnl1. Phenotypic analysis showed that the dnl1 mutant has a thinner culm and more tillers, but the number of grains per panicle, the seed setting rate and the grain weight of dnl1 mutant were found to be significantly lower than in the wild-type. Based on scanning electron microscopic observations, the number of cells in the y-axis in internodes was significantly lower than in the wild-type. In phytohormone induction experiments, dnl1 was gibberellic acid-insensitive. The expression of some genes involved in the gibberellins metabolic pathways was affected in the dnl1 mutant, based on the real-time PCR analysis, suggesting that the dnl1 gene likely plays a role in gibberellin metabolic pathways. Genetic analysis showed that the dwarf and narrow leaf phenotype is controlled by a novel single recessive gene, here referred to as the dwarf and narrow leaf 1 (dnl1), which is located within the region between markers Ind12-11 and RM8214 on the short arm of chromosome 12. By means of fine-mapping strategy, the dnl1 gene was localized within an interval of 285.75 kb physical distance. These results will be useful for dnl1 gene cloning and to improve our understanding of the molecular mechanisms involved in the regulation of growth and development of rice.

Unusual maculopathy secondary to hypergammaglobulinemia in a patient with systemic lupus erythematosus

PURPOSE

To report the unusual findings of fluorescein angiography and optical coherence tomography in a case of systemic lupus erythematosus with hypergammaglobulinemia.

DESIGN

Interventional case report.

RESULTS

A 59-year-old woman had systemic lupus erythematosus but had stopped taking medication for 6 months. Blurred vision was noted, and the fundoscopic findings revealed serous macular detachment. Results of optical coherence tomography demonstrated intraretinal and subretinal fluid, but fluorescein angiography showed no leakage. Her best-corrected visual acuity improved after posterior sub-Tenon triamcinolone injection.

CONCLUSION

Patients with atypical macular detachment may be afflicted with a serum immunogammopathy such as multiple myeloma, Waldenström's macroglobulinemia, and benign polyclonal gammopathy. Systemic lupus erythematosus should also be ruled out.

Geldanamycin, a HSP90 inhibitor, attenuates the hypoxia-induced vascular endothelial growth factor expression in retinal pigment epithelium cells in vitro

Hypoxia is the most common factor contributing to the pathogenesis of choroidal neovascularization, which is the major cause for blindness and occurs in proliferative diabetic retinopathy and age-related macular degeneration. The purpose of this study is to investigate the role of retinal pigment epithelial (RPE) cells in the regulation of subretinal neovascularization under hypoxia and the possible function of a heat shock protein 90 (HSP90) inhibitor, geldanamycin (GA), in the regulation of VEGF expression. An in vitro hypoxic experimental model was used to mimic the ischemic microenvironment of RPE cells. The cell growth was measured by proliferation assay and the morphological observation was documented by microscope. The gene expression of VEGF, hsp70, hsp90alpha and hsp90beta were measured using semi-quantitative RT-PCR. The VEGF release from RPE cells were detected by ELISA. No alteration in growth rate and cell morphology under 1% O(2) condition for 24h was noticed. The proangiogenic growth factor VEGF, but not bFGF, released from hypoxia-treated cells were significantly higher than those of normoxic controls. A similar tendency of VEGF(165) isoform gene expression, detected by RT-PCR, was noticed in hypoxia-treated cells. Heat shock pretreatment elevated hsp70 and VEGF(165) gene expression and augmented the hypoxia-induced VEGF gene expression and protein release. Pretreatment with GA can significantly suppress the hypoxia-induced VEGF gene expression in and peptide release from RPE cells. These in vitro findings suggest that HSP90 inhibitors could be considered as novel anti-angiogenesis agents for diseases with intraocular neovascularization.

Ptosis as an initial manifestation of orbital lymphoma: a case report

Ptosis on its own is an infrequent initial manifestation of orbital lymphoma. Orbital lymphoma usually presents as a palpable mass with proptosis, diplopia, and conjunctival ("salmon-pink") swelling. We report here a 62-year-old female patient who presented with right eye ptosis. The initial imaging study showed an indistinct enlargement of the superior rectus-levator muscle complex. After 3-4 months, ptosis and upward gazing movement were further restricted. The imaging study revealed a definite soft-tissue mass in the superior orbit surrounding the superior rectus-levator muscle complex. A tumor biopsy through anterior orbitotomy revealed a large diffuse B-cell lymphoma. With the experience of this case, we suggest that orbital lymphoma should be included in the differential diagnosis of ptosis accompanied by impairment of levator muscle function.

Partial liquid ventilation in normal rabbits: comparison of three kinds of perfluorocarbon

Perfluorocarbon liquids have been used in liquid ventilation studies and considered an effective technique of gas exchange with less barotrauma when compared with gas ventilation. We compared the effects of partial liquid ventilation (PLV) using 3 kinds of perfluorocarbon liquids (Fluorinert FC 43, FC 77 and FC 84) available in Taiwan in normal rabbits. We were able to achieve adequate oxygenation and ventilation during a 2-hour-duration of PLV using FC 43, FC 77 or FC 84. There was no significant difference in hemodynamic status or laboratory findings between control group and PLV groups. There were also no significant differences before LV and after 2 hours of PLV among PLV groups. Histological study of lung tissue revealed intact and well expanded alveoli, and no significant pathological change after 2 hours of PLV. These results show that PLV using FC 43, FC 77 or FC 84 is an effective technique for maintaining adequate pulmonary gas exchange in normal rabbits.

Risk factors of pulmonary hemorrhage in very-low-birth-weight infants: a two-year retrospective study

Pulmonary hemorrhage is a serious complications in very-low-birth-weight (VLBW) infants with respiratory distress syndrome (RDS). We undertook a 2-year retrospective study to investigate the predisposing factors and the incidence of pulmonary hemorrhage in VLBW infants. From January 1997 through December 1998, twenty infants were diagnosed with massive pulmonary hemorrhage (MPH) according to the following criteria: active bleeding from the endotracheal tube, acute drop in hematocrit (> or = 10%), and the development of multilobar infiltration on chest radiograph. The mean gestational age was 26.9 +/- 2.5 weeks, the mean birth weight was 909 +/- 290 g. Twenty historic controls with similar gestational age and birth weight were retrospectively identified during the study period. The incidence of MPH in VLBW infants was 5.9%(20/340). A lack of prenatal corticosteroid administration, surfactant replacement therapy for RDS, and a patent ductus arteriosus (PDA) with cardiovascular dysfunction requiring dopamine support were the significantly predisposing factors of MPH in the acute stage (< or = 7th day of life). To avoid MPH and decrease mortality and morbidity in the acute stage, prenatal corticosteroid administration, evaluation of the necessity of surfactant therapy, and early recognition and aggressive treatment of hemodynamically significant PDA were necessary.

Glucose and insulin infusion versus kayexalate for the early treatment of non-oliguric hyperkalemia in very-low-birth-weight infants

Forty very low birth weight (VLBW) infants with non-oliguric hyperkalemia in the first few days after birth were enrolled in this study. They were randomly divided into 2 groups, regular insulin (RI) infusion group and kayexalate resin enema group. Therapy was administered when serum potassium level was greater than 6 mEq/L. None of these infants received blood transfusion during this study course. In RI group (n = 20), the ratio of infusion glucose to regular insulin was 10-15 gm glucose to 1 unit RI, and the glucose infusion rate was maintained at least 6 mg/Kg/min. In Kayexalate group (n = 20), the dose of Kayexalate was 1 gm/Kg body weight given rectally every four hours. All treatment discontinued after the serum potassium level returned to normal for 6 hours. The mean gestational ages were 27.4 +/- 1.8 weeks in RI group and 28.4 +/- 2.4 weeks in Kayexalate group, respectively. Mean birth weights were 935 +/- 259 gm (RI) and 1065 +/- 214 gm (Kayexalate). The ages at onset of hyperkalemia were 24.6 +/- 8.2 (RI) and 22.2 +/- 8.1 (Kayexalate) hours after birth. The mean urine outputs during the 8-hour interval prior to development of hyperkalemia were 5.4 +/- 1.3 (RI) and 5.5 +/- 0.9 (Kayexalate) ml/kg/min. The durations of hyperkalemia were 26.4 +/- 14.9 (RI) and 38.6 +/- 13.3 (Kayexalate) hours. The peak serum potassium levels during therapy were 7.3 +/- 0.9 and 7.4 +/- 0.6 mEq/L. The incidences of grade II and above intraventricular hemorrhage (IVH) were 15% (3/20) and 50% (10/20). The incidences of cardiac dysrhythmia were 5% (1/20) and 10% (2/20). Significantly shorter duration of non-oliguric hyperkalemia and lower incidence of IVH were noted in RI group, but there were no differences in the peak potassium level or the incidence of cardiac dysrhythmia between these two groups. We conclude that to use early continuous regular insulin infusion therapy for the treatment of non-oliguric hyperkalemia in VLBW infants is more effective than kayexalate in decreasing the duration of hyperkalemia and reducing the incidence of intraventricular hemorrhage.

Activity of phosphatidylethanolamine-N-methyltransferase in brain affected by Alzheimer's disease

To determine whether phospholipid abnormality in Alzheimer's disease is associated with modification of phosphatidylethanolamine-N-methyltransferase, the activity of the enzyme was analysed in the frontal and occipital cortex of the brain from patients with Alzheimer's disease and from aged-matched control. The optimum pH for phosphatidylethanolamine-N-methyltransferase in human brain was 9.0. The enzyme activity was stimulated by detergent TWEEN 20 but inhibited by Triton X-100. Neither magnesium dependence nor chemical methylation was found. A decrease in activity of phosphatidylethanolamine-N-methyltransferase was observed in the frontal cortex of brain affected with Alzheimer's disease. The addition of exogenous phosphatidylethanolamine resulted in no modification in the methylation rate as compared with that of endogenous PE. The addition of phosphatidyl-N-monomethylethanolamine and phosphatidyl-N,N-dimethylethanolamine resulted in significantly increased rates of methylation in brain tissues. However, the increased rate of phosphatidylethanolamine-N-methyltransferase activity stimulated by exogenous phospholipids was lower in the frontal cortex of brains with Alzheimer's disease when compared to the normals and there was no difference in the occipital cortex between Alzheimer's disease and the control. It is plausible that the decreased activity of phosphatidylethanolamine-N-methyltransferase and its low compensating ability could relate to the modification of phosphatidylcholine in brain tissues from Alzheimer's disease patients.

Two selective 5-HT1A receptor antagonists, WAY-100 635 and NDL-249, stimulate locomotion in rats acclimatised to their environment and alter their behaviour: a behavioural analysis

The aim was to study firstly, the motor effects of a new 5-HT1A antagonist, NDL-249 [(R)-3-(N-cyclopentyl-N-propylamino)-8-fluoro-3,4-dihydro-2H-1-benzopyra n-5-carboxamide hydrochloride] and of the reference 5-HT1A antagonist WAY-100 635 [N-(2-(1-(4-(2-methoxyphenyl)piperazinyl))ethyl)-N-(2-pyridinyl) cyclohexanecarboxamide trihydrochloride], in comparison to the 5-HT1A agonist (+/-)-8-OH-DPAT [(8-hydroxy-2-(di-N-propylamino) tetralin, hereafter 8-OH-DPAT], in rats acclimatised to the automated activity cages; secondly, to study whether the behavioural effects of NDL-249 and 8-OH-DPAT are sensitive to the 5-HT depleting effects of p-chlorophenylalanine (PCPA); thirdly, to characterise the nature of the antagonist-induced activation seen in the automatic activity cages with the aid of a behavioural observation analysis; fourthly, to examine the interaction between the 5-HT1A receptors mediating the behavioural effects and dopamine (DA) receptors. NDL-249 was found to bind in vitro to rat hippocampal 5-HT1A receptors with high affinity and selectivity. In second messenger studies, it was devoid of agonist-like effects. In the locomotor activity studies, each antagonist significantly increased the incidence of horizontal activity, peripheral activity and rearing. 8-OH-DPAT, while significantly increasing peripheral and horizontal activities, decreased the incidence of rearing. PCPA blocked the motor effects of NDL-249 but did not affect those of 8-OH-DPAT. Observational analyses indicated that NDL-249 induced significant increases at one or more doses in sniffing, rearing and locomotion together with a significant reduction in stillness. WAY-100 635 significantly increased the incidence of rearing, intense grooming and vacuous chewing. The significant increases in sniffing, grooming and intense grooming and the significant decrease in stillness induced by the DA D1 agonist, SK&F 38393 [(+/-)-1-phenyl-2,3,4,5-tetrahydro-(1H)-3-benzazepine-7,8-diol hydrochloride], were not altered by concomitant pre-treatment with NDL-249. Pre-treatment of rats with either the DA D1 antagonist SCH-23390 (2,3,4,5-tetrahydro-3-methyl-5-phenyl-1H-3-benzazepin-7-ol) or the DA D2 antagonist, raclopride, blocked the reduced stillness and increased sniffing and rearing induced by NDL-249. In conclusion, 5-HT1A antagonists including the new selective antagonist, NDL-249, induce mild behavioural activation in rats, which is mediated probably indirectly via DA systems.

Crash risks of older drivers: a panel data analysis

Considerable progress has been made on understanding older drivers' safety issues. None the less, findings from previous research have been rather inconclusive. Differences in data and research methodology have been suggested as factors that contribute to the discrepancies in previous findings. One of the methodological limitations is the lack of considering temporal order between events (i.e. the time between onset of medical condition, symptom and crash). Without time-series data, a 'snap-shot' of medical conditions and driving patterns were often linked to more than 1 year--of crash data, hoping to accumulate enough data on crashes. The interpretation of the results from these studies is difficult in that one cannot explicitly attribute the increase in highway crash rates to medical conditions and/or physical limitations. This paper uses a panel data analysis to identify factors that place older drivers at greater crash risk. Our results show that factors that place female drivers at greater crash risk are different from those influencing male drivers. More risk factors were found to be significant in affecting older men's involvement in crashes than older women. When the analysis controlled for the amount of driving, women who live alone or who experience back pain were found to have a higher crash risk. Similarly, men who are employed, score low on word-recall tests, have a history of glaucoma, or use antidepressant drugs were found to have a higher crash risk. The most influential risk factors in men were the number of miles driven, and use of antidepressants.

A survey on the treatment strategy of patent ductus arteriosus in very low-birth-weight infants

This study is a retrospective analysis of the clinical data of 67 very low birth weight infants (VLBWI) with symptomatic patent ductus arteriosus (PDA); all were admitted to four neonatal intensive care units (NICU) from January 1, 1996 through December 31, 1996. The mean gestational age was 27.9 +/- 2.4 weeks, the mean birth weight was 1078 +/- 193 g. Fifty-six infants (83.6%) had RDS, and 53 infants (79%) received artificial surfactant. The NICU at a regional hospital used CVD score > or =3 as the sole criteria and the remaining three NICUs used color Doppler echocardiogram to confirm a symptomatic PDA and to treat it; sometimes LA/AO > or = 1.3 was used as the criteria for indomethacin treatment. Two of these three hospitals sometimes used the pulsed Doppler echocardiogram as well as color Doppler examination as the treatment criteria. Seven infants (10.5%) had contraindication for indomethacin treatment; four of them closed after conservative treatment, and another three were subjected to surgical ligation. Of the remaining 60 infants, 3 were treated with oral indomethacin and 57 were treated with intravenous indomethacin. The mean age when initial treatment given was 3.8 +/- 1.5 days (range, 8 hours approximately 20 days). Among them 10 (16.7%) were within 24 hours after birth, 25 (41.7%) were between 24 and 48 hours, and 25 (41.7%) were beyond 48 hours. The dosage of indomethacin was 0.2 mg/kg per dose intravenously every 12 to 24 hours for three doses as a full course, if not contraindicated. The mean dose of indomethacin was 2.8 +/- 1.5; 10 infants (16.7%) received 1 dose, 15 (25%) received 2 doses, 27 (45%) received 3 doses, 3 (5%) received 4 doses and 5 (8.3%) received 6 doses. Among them, 51 infants (85%) PDA closed (including 2 treated with oral indomethacin), 9 (15%) failed to close and 6 of them received surgical ligation (including 1 treated with oral indomethacin). The complications associated with indomethacin treatment were hypoglycemia (52%), decreased urine output (42%) and gastrointestinal hemorrhage (32%). The infants with RDS had an earlier mean age of initial treatment than non-RDS infants (3.3 +/- 2.5 vs. 7.6 +/- 5.6 days; p < 0.05), and also had a higher closure rate (89% vs. 57%; p < 0.05). There was a closure rate of 85% in this multicenter retrospective analysis. Even though the infants received only one or two doses, they still had a good chance of ductal closure (21/25, 84%). To minimize the complications associated with indomethacin treatment in VLBWI, the protocol of indomethacin treatment should be re-evaluated.

The pharmacological characterization of a novel selective 5-hydroxytryptamine1A receptor antagonist, NAD-299

The pharmacological properties of a novel selective 5-hydroxytryptamine1A (5-HT1A) receptor antagonist, NAD-299 [(R)-3-N,N-dicyclobutylamino-8-fluoro-3,4-dihydro-2H-1-benzopyran-5-carboxamide hydrogen (2R,3R)-tartrate monohydrate] were examined in vitro and in vivo and compared with the reference 5-HT1A receptor antagonist, WAY-100635 [N-(2-(1-(4-(2-methoxyphenyl)piperazin-yl))ethyl)-N-(2-pyridinyl) cyclohexanecarboxamide trihydrochloride]. The new compound had high affinity for 5-HT1A receptors in vitro with a Ki value of 0.6 nM. The only other receptors for which NAD-299 had affinity less than 1 microM were alpha-1 and beta adrenoceptors with Ki values of 260 and 340 nM, respectively. Thus, the selectivity of NAD-299 for 5-HT1A receptors was more than 400 times. WAY-100635 had considerably higher affinity than NAD-299 for alpha-1 adrenoceptors (Ki = 45 nM) and dopamine D2 and D3 receptors (Ki = 79 and 67 nM, respectively). Like WAY-100635, NAD-299 competitively blocked 5-HT-induced inhibition of vasoactive intestinal peptide-stimulated cAMP production in GH4ZD10 cells and had no intrinsic activity. Both compounds were therefore 5-HT1A receptor antagonists in vitro and also behaved as such in in vivo experiments. Thus, they competitively antagonized the 8-hydroxy-2-(di-n-propylamino)tetralin-induced 5-HT behavioral effects, hypothermia, corticosterone secretion and inhibition of passive avoidance behavior without causing any actions of their own. The effective dose of NAD-299 varied between 0.03 and 0.35 micromol/kg s.c., depending on the test and the dose of 8-hydroxy-2-(di-n-propylamino)tetralin.

NMDA receptor-mediated increase in cyclic GMP in the rat cerebellum in vivo is blocked by alaproclate and GEA-857

The effects of alaproclate and GEA-857 (2-(4-chlorophenyl)-1,1-dimethylethyl 2-amino-3-methylbutanoate) on the production of cyclic GMP in the rat cerebellum in vivo induced by stimulation of N-methyl-D-aspartate (NMDA) receptors were studied. Alaproclate per se at a dose of 20 mg/kg subcutaneously, did not influence the basal cGMP level. The increase in cGMP induced by harmaline (20 mg/kg subcutaneously) was dose-dependently antagonized by alaproclate (5-40 mg/kg subcutaneously). S-(-)-Alaproclate was 2-5 times more potent than the R-(+)-enantiomer. GEA-857 which in contrast to alaproclate is a very weak 5-HT uptake inhibitor shared the ability of alaproclate to inhibit the effect of harmaline on cGMP accumulation with similar potency to S-(-)-alaproclate. Alaproclate at 15 mg/kg subcutaneously blocked the increase in cGMP in cerebellum caused by NMDA itself at 200 mg/kg subcutaneously. In contrast to alaproclate, the K+ channel antagonist, 4-aminopyridine, 5 mg/kg subcutaneously, produced per se an increase in cGMP levels in the rat cerebellum by 300% which was antagonized by the NMDA receptor antagonists, dizocilpine, phencyclidine and (+/-)-CCP, the nitric oxide synthase inhibitor, NG-nitro-L-arginine methyl ester and by alaproclate. Alaproclate. Alaproclate and GEA-857 antagonized seizures induced by NMDA, 200 mg/kg subcutaneously at doses similar to those antagonizing the harmaline- and NMDA-induced elevation of cerebellar cGMP. Neither alaproclate nor GEA-857 caused any behavioural effects typical for uncompetitive NMDA receptor antagonists except a slight increase in motor activity and sniffing. The effect of alaproclate on the NMDA receptor-mediated increase in cGMP in rat cerebellum in vivo might be due to blockade of the cation channel of the NMDA receptor complex previously observed in in vitro experiments and these compounds seems to belong to the group of low-affinity uncompetitive NMDA receptor antagonists that might have clinical interest.

4-Aminopyridine-induced increase in basal and stimulation-evoked [3H]-NA release in slices from rat hippocampus: Ca2+ sensitivity and presynaptic control

1. We have examined the mechanisms by which the K(+)-channel blocker 4-aminopyridine (4-AP) can dose-dependently increase both basal [3H]-noradrenaline ([3H]-NA) release and the [3H]-NA release evoked by electrical stimulation, but not the release of [3H]-acetylcholine ([3H]-ACh), from slices of rat hippocampus. 2. Both the electrically evoked and the 4-AP-induced release were blocked by tetrodotoxin (TTX) (3 microM). The Ca(2+)-dependence of the 4-AP-induced release (EC50 0.15 mM) was, however, different from that of the electrically evoked [3H]-NA release (EC50 0.76 mM). 3. The 4-AP-induced release could be inhibited by CdCl2(10 microM) and omega-conotoxin (30 nM), but not by nifedipine (1 microM). 4. Transmitter release evoked by 100 microM 4-AP could be blocked by the alpha 2-adrenoceptor agonist, UK 14,304 (0.1 microM) and by the A1-receptor agonist R-N6-phenylisopropyl adenosine (R-PIA, 1 microM) and increased by the alpha 2-adrenoceptor antagonist, yohimbine (1 microM), both in 0.25 and 1.3 mM Ca(2+)-containing medium. By contrast, the effect of alpha 2-adrenoceptor agonist and antagonists on transmitter release evoked by electrical stimulation was markedly reduced in the presence of 4-AP (100 microM). 5. The results suggest that 4-AP can depolarize some nerve endings in the central nervous system, leading to transmitter release that is dependent on nerve impulses and Ca2+. Furthermore, the fact that alpha 2-receptors and adenosine A1 receptor agonists can influence the release of NA evoked by 4-AP suggests that these drugs may have actions that are independent of blockade of aminopyridine-sensitive K(+)-channels.

On the usefulness of Fura-2 measurements of intrasynaptosomal calcium levels in rat cortical synaptosomes to study mechanisms of presynaptic function

Levels of [Ca2+]i in rat cortex synaptosomes were measured using the Ca2+ indicator Fura-2. Ca2+ influx was induced by veratridine in a concentration-dependent manner (1-10 microM). The resulting increase in [Ca2+]i was inhibited by tetrodotoxin (TTX). K+ (18 mM) increased the [Ca2+]i which was not influenced by TTX. K(+)-channel blockers such as 4-aminopyridine, alpha- and delta-dendrotoxin pre se were ineffective. The veratridine-induced Ca2+ influx in synaptosomes was reduced by L-type Ca(2+)-channel blockers, such as felodipine, nifedipine and PN-200-110, verapamil and diltiazem. omega-Conotoxin, and N-type Ca(2+)-channel blocker, did not inhibit the veratridine-stimulated [Ca2+]i increase. Bay K 8644, and L-channel agonist, stimulated an increase of [Ca2+]i in synaptosomes which was not sensitive to TTX. R-N6-Phenyl-isopropyl-adenosine (R-PIA) and clonidine, agonists at adenosine A1-receptors and alpha 2-adrenoceptors, respectively, did not influence the veratridine-stimulated [Ca2+]i increase. R-PIA did not interact with Bay K 8644-stimulated [Ca2+]i increase in synaptosomes. The results for all the substances used show major differences between the effects on Ca2+ influx in synaptosomes and on the electrically evoked neurotransmitter release in slice preparations. Thus, the synaptosome preparation is not a generally applicable experimental model for the study of Ca2+ mechanisms of presynaptic neuromodulation.

Effect of an intracellular calcium chelator on the regulation of electrically evoked [3H]-noradrenaline release from rat hippocampal slices

1. The electrically (3 Hz, 5 min) evoked [3H]-noradrenaline ([3H]-NA) release from rat hippocampal slices was reduced by prior treatment of the slices with 1,2-bis(2-aminophenoxy)ethane-N,N,N'N'-tetraacetomethylester (BAPTA/AM) in a concentration-(10 to 500 microM) dependent manner (40% at 30 microM). Reduction of medium calcium from 1.3 to 0.5 mM caused a larger (70%) decrease. BAPTA free acid (100 mM), a non-permeable Ca(2+)-chelator had no significant effect. 2. Basal [3H]-noradrenaline release was reduced by BAPTA/AM in a concentration-dependent manner (50% at 30 microM), but reduction of external Ca2+ from 1.3 to 0.5 mM did not alter basal release. 3. About 10% of total [3H]-NA in the slices was released at 3 Hz stimulation in 1.3 mM Ca2+ buffer. Addition of the alpha 2-adrenoceptor antagonist, idazoxan (1 microM), increased electrically evoked [3H]-NA release to 26% but stimulated release was not altered by the adenosine A1-receptor antagonist, 8-cyclopentyl theophylline (8-CPT) (1 microM). 4. Evoked release was reduced by the alpha 2-receptor agonist, UK 14,304, in a concentration-dependent manner in the presence of 8-CPT (1 microM). The magnitude of this effect was not altered by the treatment of slices with 30 microM BAPTA/AM. 5. The adenosine A1 receptor agonist, N6-cyclohexyl adenosine (CHA) (1 microM) inhibited electrically evoked [3H]-NA release by about 40% in the presence of idazoxan (1 microM). The effect of CHA was not significantly altered by treatment of slices with BAPTA/AM. 7. The present results show that spontaneous [3H]-NA release is affected by reduction of intracellular Ca2+, but not by reduction of extracellular Ca2+ or by the presynaptic agonists or w-conotoxin. By contrast, electrically evoked release was affected more strongly by alterations of extracellular Ca2+ than by buffering intracellular Ca2+. The reduction of electrically evoked [3H]-NA release by agonists at the adenosine Al-receptor and a2-adrenoceptor is probably mediated through the control of Ca2+ entry via membrane ion channels or at a low affinity Ca2'-site governing evoked release.

Energy-linked transhydrogenase. Characterization of a nucleotide-binding sequence in nicotinamide nucleotide transhydrogenase from beef heart

Purified nicotinamide nucleotide transhydrogenase from beef heart was investigated with respect to labeling and subsequent sequence analysis of a nicotinamide nucleotide-binding site. A photo-activated azide derivative, 8-azidoadenosine 5'-monophosphate, was used as an active-site-directed photoaffinity label, which was shown to be specific for the NAD(H)-binding site in the dark. Light-activated incorporation of the label in transhydrogenase was accompanied by an inactivation, which approached 100% at the incorporation of about 1 mol label/mol transhydrogenase monomer. As expected from the assumed site-specificity of the label. NADH prevented both labeling and inactivation to some extent. However, NADPH also prevented labeling and inactivation marginally. The oxidized substrates NAD+ and NADP+ were inhibitory by themselves under these conditions, and the substrate analogs 5'-AMP and 2'-AMP were also poor protectors. The NAD(H)-site specificity of the azido compound was thus largely lost upon illumination and covalent modification. Radioactive labeling of transhydrogenase with 8-azido-[2-3H]-adenosine 5'-monophosphate followed by protease digestion, isolation of labeled peptides and amino-acid sequence analysis showed that Tyr 1006 in the sequence 1001-1027 close to the C-terminus was labeled. This sequence shows homologies with nucleotide-binding sequences in, e.g., F1-ATPase. On the basis of sequence homologies with other NAD(P)-dependent enzymes it is proposed that transhydrogenase contains 4 nucleotide-binding sites, of which 2 constitute the adenine nucleotide-binding domains of the catalytic sites for NAD(H) and NADP(H) close to the N- and C-terminals, respectively. Each of these domains has an additional vicinal nucleotide-binding sequence which may constitute a non-catalytic nucleotide-binding site or the nicotinamide nucleotide-binding domain of the catalytic site. The present results indicate that 8-azidoadenosine 5'-monophosphate is kinetically specific for the catalytic NAD(H)-binding site, but reacts covalently with Tyr 1006 of the putative non-catalytic site or nicotinamide nucleotide-binding domain formed by the 1001-1027 amino acid sequence of the catalytic NADP(H)-binding site. Interactions between the catalytic NAD(H) and NADP(H) binding sites, and the assumed non-catalytic sites, may be facilitated by a ligand-triggered formation of a narrow pocket, which normally allows an efficient hydride ion transfer between the natural substrates.

Comparison of the effects of four dendrotoxin peptides, 4-aminopyridine and tetraethylammonium on the electrically evoked [3H]noradrenaline release from rat hippocampus

We have examined the effects of four dendrotoxin (DaTX) peptides, alpha-, beta-, gamma- and delta-DaTX, separated from the venom of the green mamba (Dendroaspis angusticeps), on field stimulation-evoked [3H]noradrenaline (NA) release from rat hippocampus and compared their effects with those of two other inhibitors of K+ channels, 4-aminopyridine (4-AP) and tetraethylammonium (TEA). 4-AP (10-300 microM) and TEA (0.1-5 mM) facilitated the evoked [3H]NA release in a concentration-dependent manner. The evoked [3H]NA release was reduced to about half by alpha 2-adrenoceptor stimulation (UK 14,304; 100 nM) and this reduction was antagonized by 4-AP (10-100 microM), whereas TEA even at 5 mM was a poor inhibitor of alpha 2-effects. alpha-DaTX (10-200 nM) mimicked 4-AP in increasing the electrically evoked [3H]NA release and diminishing the inhibitory effects of UK 14,304 in a concentration-dependent manner. delta-DaTX did not itself alter the electrically evoked [3H]NA release, but at 200 nM, it reduced the effects of alpha 2-receptor stimulation. beta- and gamma-DaTX (up to 200 nM) had no significant effects. 4-AP, 3,4-diaminopyridine (3,4-DAP), TEA and the four dendrotoxins displaced the binding of [3H]p-aminoclonidine ([3H]PAC) from alpha 2-receptors. The IC50 values were 6.6 x 10(-4), 1.42 x 10(-3), 5.6 x 10(-2) for 4-AP, 3,4-DAP and TEA, respectively, and 3.19 x 10(-6) M for alpha-DaTX. Thus, their potency as inhibitors of alpha 2-receptors is apparently too low to account alone for the antagonism by K+ channel inhibitors of alpha 2-effects on NA release.(ABSTRACT TRUNCATED AT 250 WORDS)

The antigenic structure of HBsAg: study of the d/y subtype determinant by chemical modification and site directed mutagenesis

Lysine residue 122 of the major protein of HBsAg/adw has been shown previously to be involved in the d subtype determinant. We demonstrate here that the corresponding residue of the HBsAg/ayw, arginine 122, does not play such a critical role the y site of this antigen subtype. Thus, conversion by site directed mutagenesis of arginine 122 to lysine 122 in HBsAg/ayw does not result in the loss of y activity nor gain of d activity. Moreover, chemical modification studies of both the adw and ayw antigens with the reagents o-methylisourea and cyclohexanedione, demonstrate that arginine 122 plays at most only a minor role in this subtype antigenic site.

Alpha 2-adrenoceptor agonist-mediated inhibition of [3H]noradrenaline release from rat hippocampus is reduced by 4-aminopyridine, but that caused by an adenosine analogue or omega-conotoxin is not

The inhibitory effect of an adenosine analogue, R-PIA, and an alpha 2-adrenoceptor agonist, UK 14,304, on [3H]NA efflux from field-stimulated rat hippocampal slices was examined. The effect of 0.1 microM UK 14,304 was mimicked by 30 nM omega-conotoxin and by 10 microM cadmium chloride, inhibitors of N- and L-type Ca2+ channels. R-PIA (1 microM) had no effect per se, but caused a clear-cut inhibition after blockade of the pre-synaptic alpha 2-receptor by yohimbine. 4-Aminopyridine (4-AP) caused a dose-dependent increase in evoked transmitter release. At 30 microM 4-AP did not affect the actions of omega-conotoxin or cadmium chloride. The pre-synaptic effect of R-PIA was similarly unaffected by 30 microM 4-AP. The pre-synaptic effect of UK 14,304 was virtually abolished by 4-AP (30 microM). The effect of UK 14,304 (0.1 microM) could be partly restored by reducing the Ca2+ concentration during treatment with 4-AP (22% inhibition compared to 42% with normal Ca2+). The magnitude of increase in evoked [3H]NA efflux by yohimbine (1 microM) was decreased by 4-AP in a concentration-dependent manner from 142% increase in controls to 21% at 100 microM 4-AP. The present results indicate that NA release is reduced by somewhat different mechanisms by pre-synaptic alpha 2- and adenosine A1-receptors. Furthermore, the results indicate that pre-synaptic A1-receptors on hippocampal NA neurons do not primarily regulate 4-AP-dependent potassium channels, but they might act directly on a Ca2+ conductance.

Interaction of dihydropyridine calcium channel agonists and antagonists with adenosine receptors

We have confirmed our previous (Fredholm et al. 1986a) finding that the dihydropyridine calcium channel agonist Bay K 8644 can displace [3H]-R-PIA from its binding site, the adenosine A1-receptor. Bay K 8644 had an apparent Ki of 5.2 X 10(-6) M. The effect was shared by the two dihydropyridine calcium channel antagonists nifedipine and felodipine (Ki 4.2 and 8.7 X 10(-6) M, respectively). By contrast, two non-dihydropyridine calcium channel antagonists, verapamil and diltiazem, did not affect binding. Bay K 8644 displaced [3H]-R-PIA from its binding sites in a solubilized preparation. [3H]-XAC, a novel, potent A1-receptor antagonist ligand, was also displaced by the dihydropyridine compounds with a similar or slightly higher potency as the displacement of R-PIA. This suggests a direct interaction with the adenosine receptor rather than an effect on regulatory GTP-binding proteins. However, at 1 mumol/l neither Bay K 8644 nor nifedipine significantly attenuated cyclic AMP accumulation in rat hippocampi or the R-PIA-mediated adenylate cyclase inhibition. The results show that dihydropyridine compounds that act as agonists or antagonists on L-type calcium channels can also affect adenosine receptors. The potency of the compounds for this effect is much lower than their potency as calcium channel agonists or antagonists. The results may therefore be of more experimental than clinical significance.

Quantitative studies of the hepatitis B viral pre-S proteins: lack of correlation with the HBeAg status

Radioimmunoassays for the determination of the relative amounts of hepatitus B viral pre-S proteins present in serum samples have been developed which utilize antibodies against synthetic peptides corresponding to the amino termini of these proteins. The assays were shown to be sensitive and specific. These assays have been used to examine hepatitis B surface antigen positive human plasma samples for the presence and relative amounts of pre-S proteins. Contrary to previously published data, it was found that there is no correlation between the presence of the pre-S proteins and the HBeAg status of the plasma, but that the ability to detect the pre-S proteins is only a function of the hepatitis surface antigen titre of the plasma. It is concluded that the pre-S proteins would not serve as a useful marker for active viral replication.