Characteristics of the delayed rectifier K current compared in myocytes isolated from the atrioventricular node and ventricle of the rabbit heart

The delayed rectifier potassium current (I _K) is known to be important in action potential repolarisation and may contribute to the diastolic pacemaker depolarisation in pacemaker cells from the heart. In this study, using whole-cell patch clamp, we investigated the characteristics of I _K in morphologically normal cells from the atrioventricular node (AVN) and ventricle of the rabbit heart. Cells were held at −40 mV and 5 μM external nifedipine was used to block L-type calcium current (I _Ca,L). Significant I _K was observed with pulses to potentials more positive than −30 mV. The steady-state activation curve in both cell types showed maximal activation at between + 10 and + 20 mV. Half-maximal activation of I _K occurred at −4.9 and −4.1 mV with slope factors of 8.3 and 12.4 mV in ventricular and AVN cells, respectively. Using pulses of increasing duration, significant I _K tails after repolarisation from + 40 mV were observed with pulses of 20 ms and increased with pulses up to 100–120 ms in both cell types. Pulses of longer duration did not activate further I _K and this suggested that only the rapid component of I _K, called I _Kr, was present in either cell type. Moreover, I _K tails after pulses to all potentials were blocked completely by E-4031, a selective blocker of I _Kr. The reversal potential of I _K varied with the concentration of external K. Superfusion of AVN cells with medium containing 4, 15 and 40 mM [K⁺]_o resulted in reversal potentials of −81, −56 and −32 mV, respectively, which are close to values predicted if the I _K channel were highly selective for K. The time constants for deactivation of I _K in ventricle and AVN on return to −40 mV after a 500-ms activating pulse to + 60 mV were 480 ms and 230 ms, respectively. The faster deactivation of I _K in AVN cells was a distinguishing feature and suggests that there may be differences in the I _Kr channel protein between ventricular and AVN cells. Received: 24 July 1995 /Received after revision: 20 October 1995 /Accepted: 23 October 1995     

Cisplatin-induced long-term dynorphin A-immunoreactivity in cell somata of rat area postrema neurons

We evaluated long-term dynorphin A-immunoreactivity in the rat area postrema (AP) after the administration of cisplatin. First, rats were given 1, 5 and 10 mg/kg body weight cisplatin (i.p.) and their behavior was monitored for 72 h. We observed a delayed increase in pica 24-72 h after injection, compared to the 24 h before injection. We attributed this to the cisplatin injection. Pica was defined as an increase in the intake of non-nutritional matter such as kaolin. Administration of 1, 5 and 10 mg/kg cisplatin led to an increase in kaolin intake on day 1. Administration of 5 and 10 mg/kg of cisplatin led to decreased intake of laboratory chow (MF) on days 1–3, but 10 mg/kg cisplatin causes an excessive aggravation of their condition. Following this behavioral experiment, we immunohistochemically examined the induction of dynorphin A in the AP at 24, 48 and 72 h post-administration of 1 and 5 mg/kg cisplatin. Administration of 5 mg/kg cisplatin caused dynorphin A to accumulate gradually in the neurosoma of the AP neurons, and the numbers of positive AP neurosomata at 48 and 72 h post-administration were higher than following an equal dosage of 0.9% NaCl. These findings suggest that dynorphin A increases in the central nervous system for a long time following administration, and causes certain behavioral and clinical changes, including those related to appetite and nausea.     

Evidence of Delayed Mesangial Transport of Human IgA in Glomeruli of ddY Mice Pretreated with Sheep Anti-type IV Collagen Serum

In order to investigate whether mesangial transport by glomeruli is delayed in ddY mice pretreated with sheep anti type IV collagen serum, the mice were administered an overload of human IgA myeloma serum. Non pretreated ddY mice used as controls and both experimental and control BALB/c mice were also processed in a similar manner. The intensities of mesangial deposition of human IgA were examined periodically and were found to correlate well with deposition of mouse IgA. Both mouse and human IgAs showed a gradual increase for up to 8 experimental weeks. In the control young ddY mice, however, the overloaded mesangial human IgA quickly disappeared, presenting no appreciable mesangial deposition of autologous IgA. In sharp contrast, both the experimental and control BALB/c mice showed an initially prolonged and rather heavy mesangial deposition of human IgA, followed by a gradual decrease and somewhat light mesangial deposition of autologous mouse IgA. These results obtained using experimental ddY mice appear to confirm the possibility that non immunological local trapping, due to retardation of mesangial transport function, causes mesangial deposition of autologous mouse IgA in this particular strain. Acta Pathol Jpn 39: 289 295, 1989.     

Quinine drinking: More regulatory puzzles

Rats were permanently hypodipsic when offered a quinine adulterated fluid on a chronic basis. Plasma osmolarity and Na concentration were normal, but the quinine drinkers showed a slight hyperkalemia compared to water drinking controls. The quinine-drinking rats maintained hydromineral equilibrium through the excretion of a small amount of concentrated urine. The quinine intake was closely matched to need, and fell to near zero when food was removed or water was supplied intravenously. This harmony of intake and output was disrupted after acute hypertonic NaCl load: while the obligatory salt diuresis was no different between water and quinine drinkers, the latter did not drink (except at the lowest level of adulteration) within several hours. However, by 24 hr all had shown a delayed drinking response. This delay in drinking of quinine was also evident after non-painful intravenous NaCl infusions, but no drinking occurred after nephrectomy. Quinine drinkers were also unresponsive to isoproterenol and intracranial dipsogens. These data are discussed in terms of their implication for definitions of regulatory drinking behavior.     

食管和贲门癌原发病灶和淋巴结转移灶p53蛋白聚集变化的相关性研究

目的：通过对食管和贲门癌原发病灶和淋巴结转移病灶肿瘤抑制基因ｐ５３变化规律的研究，加深对食管和贲门癌转移发生的分子学基础的了解。方法：采用组织病理学和免疫组织化学（ＡＢＣ）方法，对３１例手术切除的食管和贲门癌原发病灶和转移病灶肿瘤抑制基因ｐ５３蛋白聚集进行比较研究。结果：３１例手术标本中，病理检查发现２４例食管鳞状细胞癌，７例为贲门腺癌。研究表明：２４例食管原发和转移鳞癌中，１１例原发和转移病灶中均出现ｐ５３蛋白聚集的变化，原发和转移病灶的一致性变化发生率为６１％（１１／１８）；在６例原发病灶ｐ５３免疫组化阴性患者中，其淋巴结转移病灶也同时出现免疫阴性反应。在７例胃贲门腺癌中，３例原发和转移病灶同时出现ｐ５３免疫阳性表达的一致率为５０％（３／６）；１例原发病灶ｐ５３免疫组化阴性患者，其淋巴结转移病灶也出现阴性反应。结论：肿瘤抑制基因ｐ５３在食管和贲门癌癌变和转移中起一定的作用。可能是食管和贲门癌侵袭与转移过程中值得重视的生物学指标之一。     

Recombination aneusomy of chromosome 5 associated with multiple severe congenital malformations

A male infant is described in whom congenital anomalies were recognized prenatally by ultrasound examination. The infant was delivered following spontaneous labor and died approximately 15 min after birth. An autopsy revealed major anomalies in the central nervous system (holoprosencephaly with premaxillary agenesis), the gastrointestinal system (esophageal atresia) and the heart (tetralogy of Fallot). Chromosomal studies revealed recombinant chromosome 5 [46,XY, rec(5), dup q, inv(5)(p15q32)], resulting in partial trisomy 5q and partial monosomy 5p. Cytogenetic investigation of the family revealed a pericentric inversion of chromosome 5 in the father and paternal grandmother, 46,XY (and XX, respectively,) inv(5)(p15q32). The congenital anomalies in this infant are more extensive and severe than previously reported in cases of recombination aneusomy involving chromosome 5.     

骨骼畸形儿童的临床研究

目的探讨骨骼畸形与晚发性佝偻病(DR)的关系.方法采用病例对照,结合临床调查,检测了85例骨骼畸形儿童及50例健康儿童的血钙、血磷、碱性磷酸酶(ALP)、骨碱性磷酸酶(BALP)、X线.结果85例5～16岁骨骼畸形儿童的临床症状主要为多汗、肢体疼痛、肢体无力、肌肉痉挛;体征以鸡胸和X形腿为多见;血钙、血磷、碱性磷酸酶检测阳性率均低,BALP测定阳性率(BALP>250U/L)为14.1%,诊断为DR,并与对照组比较,差异有显著性意义(p<0.05).结论要重视骨骼畸形儿童的诊断及DR的诊断和防治工作.     

1 MHz腔内射频加热辐射器在体模和犬颈段食管中的热场分布

目的 在肌肉等效体模及Beagle犬颈段食管中测定ZRL—Ⅱ型食管腔内加热辐射器的温度分布，探讨其热场分布能否满足食管癌加热治疗的临床需要。方法 ①在肌肉等效体模中测定ZRL—Ⅱ型食管腔内射频加热辐射器的温度分布，②Beagle犬用氯胺酮麻醉、固定。将腔内加热辐射器插入食管腔内，加热45min后分层解剖犬的颈部，同时测量食管外壁、气管、食管周围软组织中的温度。结果 ①在肌肉等效体模中距离导管囊表面1cm的环形体内的温度在43．2℃～43．6℃之间；在距离导管囊表面2cm的环形体内的温度在42．6℃～43．3℃之间，在距离导管囊表面3cm的环形体内的温度在42．6℃～42．8℃之间。②测得Beagle犬颈段食管腔内和外壁的温度为43．5℃，气管内为38．0℃，主动脉旁38．0℃，距食管外壁1cm处的软组织温度为40-3℃，距食管外壁2cm处的软组织温度为39．0℃，而颈部皮下的温度是37．5℃。结论 ①ZRL-Ⅱ型射频食管腔内加热辐射器的热场分布满足临床食管腔内加热的需要，②体模测定与活体动物测定，热场分布存在一定差异，需进一步研究。     

原发性食管小细胞癌16例临床分析

目的探讨原发性食管小细胞癌的临床特点、治疗及预后。方法回顾分析16例原发性食管小细胞癌患者的临床资料。结果1年总生存率为56．2％，2年总生存率25．0％，3年总生存率12．5％。中位生存期15．7个月。结论对于原发性食管小细胞癌应采用以化疗占主要地位的综合治疗，局限期以手术联合化疗，广泛期以放疗联合化疗为宜。