Development and Initial Testing of a Permanently Implantable Centrifugal Pump

Abstract: To be able to salvage heart failure patients, the need for an economical permanent ventricular assist device is increasing. To meet this increasing demand, a miniaturized centrifugal blood pump has been developed as a permanently implantable device. The Gyro permanently implantable model (PI-601) incorporates a sealless design with a blood stagnation free structure. The pump impeller is magnetically coupled to the driver magnet in a sealless manner. This pump is atraumatic and antithrombogenic and incorporates a double pivot bearing system. A miniaturized actuator was utilized in this system in collaboration with the University of Vienna. The priming volume of this pump is 20 ml. The overall size of the pump actuator package is 53 mm in height and 65 mm in diameter, 145 ml of displacement volume, and 305 g in weight. Testing to date has included in vitro hydraulic performance and hemolysis. This pump can provide 5 L/min against a 110 mm Hg total pressure head at 2,000 rpm and 8 Limin against 150 mm Hg at 2,500 rpm. The normalized index of hemo-lysis (NIH) value of this pump was 0.0028 g/100 L at 5 Limin against 100 mm Hg. A preliminary anatomical study revealed the possibility of the implantability of 2 such systems in biventricular bypass at a preperitoneal location. This system is feasible for use as a permanently implantable biventricular assist device.     

A case of pregnancy in a woman with cloacal dysgenesis and a rudimentary uterine horn

Cloacal dysgenesis is frequently associated with uterine anomalies. We report a case of pregnancy which resulted in an abortion in a woman with a persistent cloaca. Presumptive diagnosis before operation was ectopic pregnancy of the left tube. Postoperatively, the site of implantation of the conceptus was found to be the cavity of a unicornuate uterus in association with a rudimentary horn, the presence of which misled us to diagnose an ectopic pregnancy.      

Cyclic mechanical stretching and interleukin-1alpha synergistically up-regulate prostacyclin secretion in cultured human uterine myometrial cells.

Prostacyclin (PGI2), a potent uterine smooth muscle relaxant, is postulated to be a major prostaglandin (PG) secreted from the human myometrium. PGI2 metabolite concentrations in the maternal plasma were reported to be elevated during pregnancy, especially during labor. Recently, we developed cultured human myometrial cells from pregnant women and reported that cyclic mechanical stretching mimicking labor increased PGI2 secretion from these cells by up-regulating PGI2 synthase promoter activities. Since elevation of cervical/vaginal interleukin-1alpha (IL-1alpha) concentrations is also a characteristic feature of delivery, and IL-1alpha is a known stimulator of PG synthesis, we investigated a possible synergistic effect of cyclic mechanical stretching and IL-1alpha on PGI2 production in cultured human myometrial cells. Treatment with IL-1alpha (10 ng/ml) significantly augmented (4- to 60-fold) the secretion of PGI2, prostaglandin E2 (PGE2), prostaglandin F2alpha (PGF2alpha) and thromboxane A2 (TXA2) from cultured human myometrial cells obtained from non-pregnant and pregnant women as well as in cultured human umbilical artery and cultured human coronary artery smooth muscle cells (p < 0.05 for all comparisons). However, labor-like cyclic mechanical stretching up-regulated IL-1alpha-augmented PGI2 secretion from myometrial cells obtained from non-pregnant and pregnant women 2.1- to 2.8-fold (p < 0.05 for all comparisons), but not PGE2, PGF2alpha nor TXA2. Moreover, such an augumentation of PGI2 secretion by cyclic mechanical stretching was not observed in cultured human umbilical artery nor in cultured human coronary artery smooth muscle cells. These results suggest that cyclic mechanical stretching by labor, in concert with IL-1alpha stimulation, contributes to the increase in myometrial PGI2 secretion during delivery.     

Pharmacokinetic and clinical studies with imipenem/cilastatin sodium in the pediatric field. Pediatric Study Group for Imipenem/Cilastatin Sodium

Pharmacokinetic and clinical studies of imipenem/cilastatin sodium (MK-0787/MK-0791), a new carbapenem antibiotic and a dehydropeptidase-I inhibitor, respectively, were carried out in a joint study in the pediatric field by a study group consisting of investigators at 16 institutions. The results were summarized below. Pharmacokinetic studies Peak plasma concentrations of MK-0787/MK-0791 were 27.7-190.0/28.3-216.4 micrograms/ml at doses of 10/10-50/50 mg/kg administered by a 30 or 60-minute drip infusion. The above findings proved that dose response was clearly observed. Over a period of 6 or 7 hours, the urinary excretion of MK-0787 and MK-0791 totaled 54.2-88.0% and 53.6-89.0% of the dose administered, respectively. Plasma half-lives of MK-0787 and MK-0791 in the beta-phase were 0.87-1.05 hours and 0.59-0.95 hour, respectively. The cerebrospinal fluid (CSF) levels of MK-0787 in patients with purulent meningitis were 2.0-14.4 micrograms/ml; however, the penetration rate of the drug into the CSF was relatively poor in patients with normal meninges. Clinical study Clinical efficacy was evaluated in 283 patients. In 112 patients the daily dosage ranged from 30/30 mg/kg to 59/59 mg/kg, and in 138 patients it ranged from 60/60 mg/kg to 99/99 mg/kg. The maximum dose administered was 222/222 mg/kg. The drug was administered either 3 or 4 times per day. The clinical efficacy rate was 92.5% among 187 patients with identified etiologic pathogens. The drug was effective in 3 out of 4 patients with purulent meningitis and in 7 out of 10 patients with septicemia. The clinical efficacy rate was 96.7% in 90 patients with respiratory tract infection (pneumonia, lung abscess, etc.), 96.5% in 57 patients with urinary tract infection, 90.9% in 11 patients with SSTI. The clinical efficacy rate in those with no identified etiologic pathogen was 97.0% among 101 patients. Bacteriologically, the eradication rate for S. aureus was 87.9% of 33 isolates. Comprehensively, the eradication rate for Gram-positive bacteria was 94.7% of 75 isolates. The eradication rate for P. aeruginosa was 87.5% of 8 isolates. Including these strains, the eradication rate for Gram-negative bacteria was 90.3% of 134 isolates. The MK-0787/MK-0791 exhibited an eradication rate of 91.9% among a total of 211 Gram-positive and Gram-negative bacteria including anaerobes.(ABSTRACT TRUNCATED AT 400 WORDS)     

Low-pressure Pneumoperitoneum for Laparoscopic Surgery Using a Disposable,Flexible Abdominal Wall Retractor

Abstract: Since April 1991, we have studied 160 patients who had had a successful laparoscopic cholecystectomy. Nine patients who presented with chronic cholecystitis with severe local adhesion and who were also considered to require a longer operative time were selected as suitable candidates for this procedure. They were successfully treated under a zero- to four-mmHg low-pressured pneumoperitoneum procedure combined with total abdominal wall lifting using a disposable, flexible vinyl tube retractor. This method enabled exactly the same clear laparoscopic vision as is possible in the routinely-used high-pressure pneumoperitoneum even in the marginal portions of the abdominal cavity. Moreover, it facilitated early reinsufflation after the cauterization-produced smoke was exhausted, which minimized the operative time and reduced the surgeon's anxiety concerning the maintenance of a sufficiently airtight condition. We believe that this low-pressure pneumopeqitoneum procedure also benefits the poor-risk patient who has restricted cardiopulmonary function, especially during advanced laparoscopic surgery which requires a longer operative and anesthetic time.