主动脉内球囊反搏在小儿中的应用

主动脉内球囊反搏(intraaortic balloon pump，IABP)已广泛应用于成年人心源性休克和围手术期低心排血量综合征的治疗，并取得良好的治疗效果，但在小儿中的应用仍较局限。现就有关IABP在小儿中的应用进行综述，着重分析IABP的适应证和影响在小儿中应用的技术困难和其他因素，介绍小儿IABP应用的技术要点，可能的并发症和治疗效果。在无体外膜式氧合器(ECMO)和左心辅助设备的情况下，小儿心脏直视手术后如不能脱离体外循环机或发生严重低心排血量综合征等，应用IABP治疗可收到较好的效果。     

嗜麦芽窄食单胞菌临床株的多重耐药外排泵的研究

目的　研究嗜麦芽窄食单胞菌临床株外排泵SmeDEF的表达与耐药的关系及其表达调控。方法　琼脂稀释法检测嗜麦芽窄食单胞菌对抗生素敏感性并检测泵抑制剂的作用 ,提取临床菌的RNA进行smeD的RT PCR扩增。提取DNA进行smeT片段的PCR扩增 ,扩增产物进行序列分析。结果　随机选取的 6株嗜麦芽窄食单胞菌均有扩增产物。SmeT的N端氨基酸序列相当保守 ,smeD smeT间区测序发现耐药且泵抑制阳性株基因序列与敏感株明显不同。推测与耐药有关的突变出现在smeT的 82～ 16 5区间。结论　嗜麦芽窄食单胞菌临床株SmeDEF外排泵的表达强弱与其耐药性有关。smeDEF基因的表达可能与调控基因间区的变化有关。     

冰点下降法测定血、尿渗透压的临床应用及注意事项

本文应用溶液冰点下降法测定了178例正常血清渗透压。结果为287±13毫渗量/kg水。并对20例尿崩症病人在限水加压素试验过程中测定血清,尿渗透压。尿崩症病人尿渗透压明显低于正常人。注射加压素后,尿渗透压升到正常。在多尿症的鉴别诊断中,此法是一种简便,灵敏的手段。有重要的诊断价值。     

Eradication of Helicobacter pylori heals atrophic corpus gastritis caused by long-term treatment with omeprazole

 Long-term treatment with proton pump inhibitors in patients with Helicobacter pylori gastritis can lead to atrophic changes in the corpus mucosa. What is still unclear, however, is whether this atrophy can regress in response to Helicobacter pylori eradication. We report on a male patient with Helicobacter pylori gastritis receiving long-term treatment (4 years) with omeprazole for gastro-oesophageal reflux disease, who developed autoaggressive gastritis with progressive atrophy, hypochlorhydria, hypergastrinaemia and nodular ECL-cell hyperplasia. To determine whether these changes might be induced to regress, Helicobacter pylori eradication therapy was administered. Ten months after Helicobacter pylori eradication autoaggressive lymphocytic infiltrates were no longer detectable, and the glands in the corpus mucosa had normalised despite continued treatment with omeprazole – a finding that was confirmed at two further follow-up surveys performed at 6-month intervals. This case report shows that atrophy of the corpus mucosa developing under long-term treatment with a proton pump inhibitor can be cured by eradicating Helicobacter pylori. Received: 21 April 1998 / Accepted: 10 August 1998     

Vasopressin induced rhythmic activity in rat basilar artery

The effects of vasopressin on membrane potential and tension were studied in isolated segments of basilar arteries from the University of Iowa colonies of normotensive inbred Kyoto-Wistar rats (WKY) and stroke-prone spontaneously hypertensive rats (SP-SHR). In the presence of vasopressin (0.01–0.3 IU/ml), basilar arteries from WKY, but not from SP-SHR, developed rhythmic contractions. These contractions were recorded in 13 of 14 WKY basilar arteries, were unaffected by pretreatment with 6-hydroxydopamine, and were characterized by 20–100 dyne oscillations in tension, occurring 1–3 cycles/min, and superimposed on the vasopressin-induced contraction (averaging 60 dynes at 0.01 IU/ml or 160 dynes at 0.3 IU/ml). However, resting membrane potentials were not different in SP-SHR vs. WKY at 37°C, and both strains showed about the same (11 mV) depolarization by 0.1 IU/ml of vasopressin. The rhythmic contractions were enhanced by K⁺-free solution, and abolished in the presence of high K⁺ solution (30 mM), suggesting that active Na⁺−K⁺ transport may be involved in modulating the rhythmic activity. These findings are consistent with the hypothesis that the vasopressin-induced rhythmic contractions in WKY basilar arteries are at least partly dependent on a reduced activity of electrogenic Na⁺−K⁺ active transport in WKY as compared to SP-SHR. This research was supported by Grant Nos. HL14388 and HL16328 from the National Institutes of Health. Dr. Rusch is the recipient of Postdoctoral Fellowship HL06907.     

Primary sequence and functional expression of a novel β subunit of the P-ATPase gene family

The cortical collecting tubule (CCT) of the mammalian kidney reabsorbs sodium and potassium, processes that are mediated by Na/K-ATPase and H/K-ATPase. CCT is also an important site for proton secretion, which is driven, in part, by H/K-ATPase. Na/K-ATPase and H/K-ATPase are members of the ion-motive P-ATPase gene family. They are closely related plasma membrane proteins which consist of heterodimers. The urinary bladder of the toad Bufo marinus is the amphibian counterpart of mammalian CCT. We have previously characterized a ouabain-resistant Na/K-ATPase [see ref. 17], from TBM cells, a clonal cell line derived from the toad bladder, which expresses transepithelial sodium transport. In the present study, we report the primary sequence and functional expression of a novel subunit ( _bladder= _bl) isolated from a toad bladder epithelial cell cDNA library. The deduced polypeptide is 299 amino acids in length and has a predicted molecular mass of 33 kDa. The _bl protein exhibits 35% amino acid identity to the previously characterized ₁ of B. marinus Na/K-ATPase and 39% identity with ₃ of B. marinus Na/K-ATPase. It shares 38% identity with the mammalian gastric H/K-ATPase and 52% with the mammalian ₂ Na/K-ATPase. Northern blot analysis shows that a 1.4×10³-base mRNA is expressed at a high level in bladder epithelial cells and eye and at a trace level in kidney; it is not detectable in significant amounts in the stomach, colon and small intestine. The _bl subunit can associate with the ₁ subunit of B. marinus Na/K-ATPase to form a functional sodium pump in the Xenopus laevis oocyte. Our data indicate that, in addition to the known ₁ and ₃ isoforms, a third distinct isoform of the subunit is present in the bladder epithelium. This new isoform could be functionally associated with subunits of either Na/K- or H/K-ATPase.     

The fourth-generation centrifugal blood pump

 The NEDO Gyro permanently implantable (PI) centrifugal blood pump has been developed as a simple, durable, centrifugal blood pump without a complex magnetic suspension system. In vitro studies were performed using a Gyro PI pump with the transparent pump housing in a mock circuit. These studies revealed that the impeller transfers to a floating or a top contact condition, which was dependent on the revolutions per minute (RPM). This pump can be easily converted from a left ventricular assist device (LVAD) to a right ventricular assist device (RVAD) by simply adding a spacer between the pump and the actuator. In order to optimize the impeller suspension for the LVAD and RVAD, spacers of the proper thickness are inserted between both of the pumps and the actuators to regulate the magnetic force. Two Gyro PI pumps were implanted in a bovine model in a 3-month biventricular assist device (BVAD) animal study. This experiment was electively terminated 90 days after implantation. All of the parameters, including pump flow rate, power consumption, and plasma free hemoglobin, were in acceptable ranges. No thrombus formation was observed in either pump. Antithrombogenesis and effectiveness were demonstrated in this animal study. The NEDO Gyro PI pump is ready to move on to the 3-month preclinical system evaluation. Received: February 28, 2002 / Accepted: May 30, 2002 Acknowledgment The New Energy and Industrial Technology Development Organization (NEDO) under the Ministry of Economy, Trade and Industry of Japan financially supported this project. Correspondence to:S. Ichikawa     

Pressure-flow relationships of the canine iliac periphery and systemic hemodynamics: Effects of sodiumnitroprusside and adenosine

It has been reported that sodiumnitroprusside (SNP) decreases mean systemic pressure and simultaneously increases pressure pulse amplification towards the iliac periphery (Kenner and van Zwieten 1982). This unexpected finding was suggested to be due to a decrease in iliac peripheral resistance but an increase in iliac differential resistance. In order to investigate this apparent contradiction, the iliac periphery was hemodynamically isolated from the rest of the circulation and perfused with the dog's own blood by means of a pump. Perfusion pressure (P) and flow (F), femoral venous pressure (P_v), systemic pressure (P_s) and cardiac output (CO) were measured. Steady state pressure-flow relations of the isolated bed were obtained during control and during various i.v. infusion rates of SNP and adenosine (ADS) and were found to be straight (meanr=0.99). Their slope (P/F) was defined as differential resistance (R_d). Peripheral resistance (R_p) of the iliac bed was defined as R_p=(P-P_v)/F, calculated at the flow value where perfusion pressure equalled the prevailing systemic pressure. Total peripheral resistance (TPR) was defined as TPR=P_s/CO. The changes of R_d, R_p, P_s, CO and TPR with respect to control show that during low SNP infusion rates R_d and R_p were both increased while TPR was decreased. During all infusion rates of SNP CO did not change while P_s decreased. During low infusion rates of adenosine CO increased while P_s, R_d and R_p did not change and TPR decreased. During high infusion rates of ADS CO decreased again, R_d, R_p and P_s decreased, and TPR remained constant but at a decreased level.It is concluded that: (1) the suggestion of Kenner and van Zwieten is not supported, since SNP (as well as ADS) affects iliac peripheral and iliac differential resistance in a similar way; (2) SNP (as well as ADS) affects iliac peripheral resistance and total peripheral resistance in a differentiated way, and even in an opposite way during low infusion rates of SNP; (3) it is this opposite effect that explains the paradoxical observations of Kenner and van Zwieten; (4) for comparable reductions of TPR, CO is better maintained during infusion of SNP, while P_s is better maintained during infusion of ADS.     

Cellular and segmental distribution of Ca2+-pump epitopes in rat intestine

We used a monoclonal antibody (5F10) specific for the human erythrocyte plasma membrane Ca⁺⁺-pump to demonstrate the presence and distribution of Ca⁺⁺-pump epitopes in rat intestine. In paraffin embedded tissue sections, antibody 5F10 binds to epitopes in the basolateral membranes of absorptive cells in rat duodenum and portions of jejunum but not ileum. Western blot analysis of intestinal mucosal proteins with antibody 5F10 shows binding of antibody to major bands of Mr 135,000 and Mr 72,000, and to lesser bands of Mr 125,000 and Mr 27,000. This pattern was seen in mucosal homogenates of rat duodenal and jejunal cells and to a lesser extent in ileal cells. The Mr 135,000 band corresponds to the molecular weight of Ca⁺⁺-pumps in other tissues. The other bands correspond in size to known proteolytic fragments of the Ca⁺⁺-pump. Slot-blot analysis of nitrocellulose immobilized mucosal homogenates shows binding of 5F10 to be greatest in duodenum and least in ileum. Ca⁺⁺- transport studies by the everted gut sac technique show a correlation between vitamin D induction of active Ca⁺⁺-transport and the segmental distribution of Ca⁺⁺-pump epitopes.     

Hyperpolarizing current of the Na/K ATPase contributes to the membrane polarization of the Purkinje cell in rat cerebellum

 The contribution of the Na/K ATPase (pump) current to the polarization of the Purkinje cell has been studied using slices of the rat cerebellum by blocking the pump with dihydro-ouabain (DHO) while recording the membrane potential with microelectrodes in the somata. From our recordings, it appeared that blocking the pump depolarized the Purkinje cells more rapidly than might be expected from shifts in Na⁺ and K⁺ concentrations, suggesting the removal of a hyperpolarizing current. Application of DHO, in the presence of tetrodotoxin (TTX), led to calcium spike firing and plateau-like discharges suggesting activation of voltage-dependent calcium channels in the dendrites. Adding 2 mM Co²⁺ to the medium did not prevent the depolarizations. Removing calcium from the bathing medium containing 2 mM Co²⁺ blocked the spiking activity but DHO application still produced a depolarization. Experiments to measure the current inhibited by DHO indicated that the Na/K pump supplies a constant current of 240 pA. Substitution of the sodium with choline produced a hyperpolarization, during which DHO had no effect on the membrane potential. Substitution of the sodium with lithium produced only a slowly developing depolarization. It is concluded that in the cerebellar Purkinje cell, a continuous sodium ion influx activates the pumps which produce a current that directly contributes to the membrane polarization. Possible pathways for this sodium influx are discussed. Received: 3 April 1997 / Received after revision and accepted: 12 May 1997