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The neck nystagmus and its changes under the influence of an otolith stimulus--centrifugal force were studied in pigeons. The results show that centrifugal forces exert a dynamic effect on the nystagmus.
An electrophysiological method was used to study the centrifugal inhibition of the impulse activity of taste receptors of the frog tongue. A deficiency of catecholamines in the organism (reserpinization) or perfusion of the adrenaline-blocking agents through the lingual vessel (propranololi hydrochloridum, dibenamine) were found to prevent the centrifugal inhibition, while perfusion with an adrenomimetic agent (epinephrine) enhanced this effect. Such effects of the adrenergic agents were also observed in the animals which were subjected to desympathization by bilateral extirpation of the first ganglion of the sympathetic chain. A conclusion was drawn that catecholamines in the papilli were necessary to obtain the central inhibition influences on the function of the taste receptor apparatus.
Compactness and high performance are the most important requirements for a cardiopulmonary support system. The Nikkiso (HPM-15) centrifugal pump is the smallest (priming volume; 25 ml, impeller diameter; 50 mm) in clinically available centrifugal pumps. The Kuraray Menox (AL-2000) membrane oxygenator, made of double-layer polyolefin hollow fiber, has a minimum priming volume (80 ml) and a low pressure loss (65 mm Hg at 2.0 L/min of blood flow) compared with other oxygenators. The aim of this study was to evaluate the performance of the most compact cardiopulmonary support system (total priming volume: 125 ml) in animal experiments. The cardiopulmonary bypass was constructed in a canine model with the Nikkiso pump and Menox oxygenator in comparison with a conventional cardiopulmonary support system. The partial cardiopulmonary bypass was performed for 4 h to evaluate the gas exchange ability, blood trauma, serum leakage, hemodynamics, and blood coagulative parameters. The postoperative plasma free hemoglobin level of the compact cardiopulmonary system was 29.5 +/- 10.21 mg/dl (mean +/- SD), which was lower than that of the conventional cardiopulmonary system, 48.75 +/- 27.39 mg/dl (mean +/- SD). This compact cardiopulmonary system provided the advantage in terms of reduction of the priming volume and less blood damage. These results suggested the possibility of miniaturization for the cardiopulmonary bypass support system in open-heart surgery in the near future.
BACKGROUND: The lysis-centrifugation system (Isolator system) is a technique with excellent results in the recovery of mycobacteria from blood specimens. This system consists mainly of saponin (SAP), polypropylenglycol (PPG), and sodium polianthol sulfonate (SPS). The objective of this work was to determine the effect of SAP, PPG, and SPS on the growth of Mycobacterium avium, M. kansasii, M. tuberculosis, and M. xenopi in fluid culture media MGIT and Septi-Chek AFB. METHODS: Two concentrations each of SAP, PPG, and SPS were prepared, and were added in 0.1 ml amounts (alone, in pairs and in combination) to fluid media MGIT and Septi-Chek AFB. Fluid culture media were then in individually inoculated with two different concentrations (10(3) and 10(5) CFU/ml) of each of the four mycobacterial strains used in this study. Culture media were incubated at 37 degrees C and were checked for growth daily. RESULTS: SAP, PPG, and SPS did not inhibit growth of mycobacteria but growth of these strains was indeed retarded (a lengthier time was required for detection of bacterial growth compared with the positive control). Final concentrations of SAP, PPG, and SPS which retarded mycobacterial growth varied, depending upon species, mycobacterial inoculum size, and fluid culture media used. CONCLUSIONS: Components included in the lysy-centrifugation system (SAP, PPG, and SPS), either alone or in combination retarded growth of M. avium, M. kansasii, M. tuberculosis, and M. xenopi in 10(3) and 10(5) CFU/ml concentrations in fluid culture media MGIT and Septi-Chek AFB. These results suggest that strategies should be adopted to decrease the concentrations of these three components, present in the sediment of the processed blood by the Isolator System, which eventually are going to be added to fluid media MGIT and Septi-Check AFB.
BACKGROUND: Right heart failure after heart transplantation represents a life-threatening complication. When conventional therapy including NO-inhalation fails the only choice to reach sufficient haemodynamic conditions may be the implantation of a right ventricular support system. METHODS: In all cases the Biomedicus centrifugal pump was implanted by cannulation of the right atrium and pulmonary artery. RESULTS: Since March 1989 950 heart transplant procedures were performed at our center. In nine cases (7 male, 2 female, mean age 52 years) implantation of a right ventricular support system was necessary because of deterioration of right ventricular function. The implantation was carried out in 7 cases immediately after transplantation, in 2 cases after 2 days. The support time ranged from 4-348 hours. Six patients could be weaned, 2 patients underwent retransplantation and died and 1 patient died on the support system. Three of the six weaned patients died in the further course because of multiorgan failure. CONCLUSIONS: Mechanical right ventricular support is often the only therapeutical tool to reach adequate haemodynamic conditions in post-transplant right heart failure. The Biomedicus centrifugal pump provides good conditions in these cases. Weaning is often possible after short-term support. The mortality rate is determined by multiorgan failure in immuno-suppressed patients. Retransplantation seems not to be successful despite maximal treatment.
We describe serpiginous erythema with alopecia developing on the scalp of a 10-year-old boy during follow-up of centrifugal lipodystrophy. Because the clinical and histopathologic features of these lesions were identical to those of centrifugal lipodystrophy, we conclude that involvement of a hairy region by this disorder could cause alopecia and that the hair loss might be an indirect effect of interstitial inflammatory infiltrates around the hair follicles and in the subcutaneous fat.
The purpose of this investigation was to analyze how left ventricular assist device (LVAD) with a centrifugal pump alters left ventricular diastolic hemodynamics and energy by means of a left ventricular pressure volume relationship. Fifteen anesthetized normal pig hearts were studied after placement of an apical drainage LVAD with a centrifugal pump. Indices of the left ventricular isovolumic relaxation phase, left ventricular filling phase and general hemodynamic data were recorded with the LVAD in on and off situations. The pump assist rate was adjusted to 25%, 50% and 75%. Left ventricular stroke work, with a high correlation with oxygen consumption, decreased as the assist rate increased. Left ventricular relaxation delayed as the assist rate increased, but the atrioventricular pressure gradient increased in the left ventricular rapid filling phase. This finding clarifies left ventricular rapid filling. In this study, it was suggested that although left ventricular isovolumic relaxation was affected, 75% assistance is the most effective for the pump flow in terms of circulation support and restoration of cardiac function.
The patient was 67-year-old woman with mitral valve restenosis and regurgitation, tricuspid insufficiency, and left atrial dilatation who underwent mitral valve replacement, tricuspid valvuloplasty, and left atrial plication. The patient developed right ventricular (RV) failure due to RV infarction when she was weaned from cardiopulmonary bypass (CPB). Therefore, CPB was resumed to be followed by intra-aorta balloon pumping (IABP). However, complete response was not obtained. Thus, right ventricular support was performed using a centrifugal pump, and the patient could be weaned from CPB. Three days after surgery, the right ventricular support was discontinued, and IABP was removed 7 days after surgery without marked changes in hemodynamics. Although RV failure due to RV infarction is a serious intraoperative complication, favorable results were obtained by combination therapy with IABP and right ventricular support using a centrifugal pump in our patient.
In order to evaluate the applicability of the organic polymeric flocculants (OPF) in the treatment of oil refinery sludge, experiments were conducted to show that OPF have better performance of flocculation than inorganic flocculants. Both the anionic and cationic OPF have satisfactory flocculation efficiency in oil sludge treatment, but the latter are more cost-efficient. Among the over 20 types of flocculants tested, 2 OPF (CPAM-2 and HPAM-2) were selected as the treatment agents, based on their good treatment performances, oil-resistance and economic feasibility. It was demonstrated in the industrial-scale centrifugal dewatering experiments that the application of either CPAM-2 or HPAM-2 could achieve high treatment efficiency of the oil sludge dewatering and reduce the COD of centrifugal liquid to less than 1000 mg/L.
A combined centrifugal, biochemical, and electron microscopic study of the cytoplasmic particulates present in 0.88 M sucrose homogenates of rat liver has been carried out. Size distribution analyses of particles containing pentose nucleic acid (PNA) and exhibiting several types of enzymatic activity revealed three major size groups within the range of particle radius between 10 and 500 mmicro. A different array of biochemical properties was associated with each size group. The largest particles, with an average radius (assuming spherical shape) in the region of 220 to 260 mmicro, contained all of the succinic dehydrogenase activity of the cytoplasmic extract, 29 per cent of the diphosphopyridine nucleotide (DPN)-cytochrome c reductase activity, and minor amounts of PNA and acid phosphatase activity. Cytologically, this group of particles was identified with the mitochondria. All of the uricase activity, 58 per cent of the acid phosphatase activity, and 26 per cent of the PNA was apparently associated with a second size group of particles (average radius 120 mmicro) which were tentatively identified by electron microscopy with vesicular structures derived from the ergastoplasm of the intact cell. The third particle group demonstrated by centrifugation exhibited a major size distribution peak at 25 mmicro and a second smaller peak at 55 mmicro. Over 50 per cent of the total cytoplasmic PNA and DPN-cytochrome c reductase activity was associated with particles in this size group. Electron microscopy revealed a morphologically heterogeneous population of particles within this size range.
The efficacy of centrifugal pumps for short-term (0-30 days) ventricular support has been widely reported and favorably compared with pulsatile systems. A small, durable, implantable centrifugal blood pump is being developed for medium-term use (up to 6 months). The pump is based on the Medtronic Hemadyne system that has existed in multiple forms over the past 30 years. The pump is approximately the size of a tennis ball, weighs 240 g, and is comprised of a 2.5 cm plastic impeller driven by a radially coupled brushless DC motor. In vitro hydraulic performance was recorded over a wide range of flow conditions on a mock circulatory loop. The pump generated 7 L/min flow against an afterload of 100 mmHg pressure, with a maximum power draw of 10.4 watts. Pulsatile flow was preserved when placed in conjunction with a simulated left ventricle. In vivo testing was performed in 10 healthy sheep for 10-292 hr. Heparin was used to facilitate cannulation, and no anticoagulation was administered after pump implantation. Blood chemistries reflecting hematologic, pulmonary, renal, and hepatic functions were recorded and demonstrated no adverse effects with normal pump operation. Complications were related to kinking of blood conduits and thrombus formation within the cannulae. These results are encouraging and warrant further studies to prove feasibility of this pump as a medium-term implantable ventricular assist device.
INTRODUCTION: Microgravity causes the deconditioning of many physiological systems, and there is great interest in developing effective countermeasures. We recently developed a short-arm human-powered centrifuge, and the primary objective of this study was to assess the hemodynamic and metabolic responses to exercise under hypergravity conditions. METHODS: Phase I compared the hemodynamic and metabolic responses to 1 Gz (upright cycle ergometry) and 2 Gz conditions (Space Cycle) at the same work rate. Phase II contrasted the hemodynamic and metabolic responses at 2 and 3 Gz and at the same work rate. Phase III examined the BP and heart rate (HR) responses during passive and active centrifugation. Phase IV examined the relationship between work rate and oxygen uptake. RESULTS: In Phase I, the HR and BP responses were very similar between the two Gz conditions, with the exception that 2 Gz produced a lower diastolic BP in female subjects. In Phase II, both systolic and diastolic BPs were similar under the two different Gz conditions. However, there was a significant increase in HR at 3 Gz. In Phase III, the slope of the HR/Gz relationship was greater for passive conditions, suggesting that venous return is facilitated by the skeletal muscle pump. In Phase IV, it was found that there was a highly linear relationship between work rate and oxygen uptake. CONCLUSION: The results of this study demonstrate that exercise under low hypergravity conditions on the Space Cycle is well tolerated from a hemodynamic perspective.
OBJECTIVE: It is an everyday routine in laboratories to encounter interference in the analysis of lipids. These likely interferences (hemolysis, icterus and lipemia) are countered by asking physicians and patients to send fresh and properly collected samples. At the Aga Khan University (AKU) Laboratory, we receive 2-3 lipemic/turbid samples per day. Previously it was our departmental policy to advise these patients to go for lipoprotein electrophoresis, which though accurate was time consuming and not cost effective. We therefore studied ultra centrifugation/airfuge as an alternate method to clear lipid interference and provide accurate, reliable and cost effective results. METHODS: Daily 2-3 grossly turbid samples are identified on the lipid bench, 48 samples were received in 4 months (February to May 2004). These samples were analyzed for total cholesterol (TC) and High Density Lipoprotein-Cholesterol (HDL-C) before and after ultra centrifugation/airfuge. RESULTS: There was a positive correlation between the lipemia and the false high TC and HDL-C. The mean TC and HDL-C before ultra centrifugation were 263.06 mg/dl and 39.42 mg/dl respectively and after centrifugation these became 191.77 mg/dl and 33.06 mg/dl. P value showed a significant difference in both results. CONCLUSION: This study suggests that the removal of turbidity by ultra centrifugation/airfuge is cost effective, less time consuming and provides accurate reliable results of TC and HDL-C in patients with lipemia interference.
Electrical failure during cardiopulmonary bypass (CPB) has previously been reported to occur in 1 of every 1500 cases. Most heart-lung machine pump consoles are equipped with built-in battery back-up units. Battery run times of these devices are variable and have not been reported. Different conditions of use can extend battery life in the event of electrical failure. This study was designed to examine the run time of a fully charged battery under various conditions of pump speed, pressure loads, pump boot material, multiple pump usage, and battery life. Battery life using a centrifugal pump also was examined. The results of this study show that battery life is affected by pump speed, circuit pressure, boot stiffness, and the number of pumps in service. Centrifugal pumps also show a reduced drain on battery when compared with roller pumps. These elements affect the longevity and performance of the battery. This information could be of value to the individual during power failure as these are variables that can affect the battery life during such a challenging scenario.
Twelve children aged 6 days to 12 years had left or common atrial to aortic extracorporeal support with a centrifugal pump after cardiac operations. Left ventricular assist time ranged from 38 to 190 hours. Ten patients were successfully weaned from left ventricular assist device support; four hospital deaths occurred afterward. All six survivors were discharged from the hospital with improved left ventricular function. Although the follow-up time is short and the experience limited, we consider the centrifugal pump type of left ventricular assist device to be a potentially lifesaving treatment modality for selected pediatric patients having cardiac operations.
We evaluated the TDx Digoxin II (Abbott) modified procedure for interference from digoxin-like immunoreactive factors (DLIF) in pediatric patients. The effectiveness of centrifugal ultrafiltration as a means of removing DLIF interference from the serum of such patients was assessed. We used sera from 40 patients who had not received digoxin, whom we divided into two age groups: 30 neonates (less than 34 days postpartum) and 10 infants (younger than six months). Digoxin-like immunoreactivity was detected in 34 of 41 (83%) neonatal specimens (range 0.2-1.0 micrograms/L) and 16 of 25 (60%) infants' specimens (range 0.2-1.3 micrograms/L). Centrifugal ultrafiltration of serum specimens from these patients reduced but did not eliminate the DLIF interference in some specimens. A comparison of concentrations of DLIF in serum with various other patients' characteristics demonstrated a strong correlation (r = 0.915; P = 0.0001) between DLIF and serum bilirubin in the infants. Apparent digoxin concentrations from 19 serum and serum ultrafiltrate samples collected from 13 patients (four neonates and nine infants) who were treated with digoxin showed a good correlation (r = 0.97); however, the serum samples showed a positive bias of 0.39 microgram/L. We conclude that the TDx Digoxin II modified procedure is still subject to considerable DLIF interference in these two pediatric populations. This interference can be reduced in some serum specimens, but cannot be eliminated completely as others reported.
The authors used the Sarns centrifugal pump (Sarns 3M, Ann Arbor, MI) as a ventricular assist device (VAD) in 30 patients between May 1985 and February 1990. Sixteen patients were unweanable from cardiopulmonary bypass at the time of surgery; nine were patients who developed cardiogenic shock postoperatively in the intensive care unit. One was a donor organ failure; one had a failed PTCA; and one an acute myocardial infarction with cardiogenic shock preoperatively. Two patients were bridged to cardiac transplantation. Of the 28 nontransplant candidates, 20 (71.4%) were weaned successfully, 14 (50%) were discharged from the hospital, and 13 (46%) are alive from 1 to 46 months postoperatively (mean, 21.1 months). Three patients received right ventricular support alone; all three were weaned, and two (66.7%) were discharged. Ten patients received left ventricular assistance alone. Six (60%) were weaned, and four (40%) were discharged. Two patients received left ventricular support initially but were taken back for right VAD insertion because of right-sided heart failure; one (50%) is alive. Fifteen patients received biventricular support. Eleven (77.3%) were weaned, and eight (53.3%) were discharged. Patient ages ranged from 19 to 73 years, with a mean age for men of 59 years and 50.5 years for women. There were no thromboembolic events. Various clinical parameters were evaluated to determine effect on weanability and survival. These results show survival equivalent to any other VAD at this time. The centrifugal pump is a convenient and effective means of maintaining ventricular support in individuals who are believed to have salvageable myocardium.
Prompt left ventricular assistance by the centrifugal pump enables the survival of many patients with postoperative low cardiac output who cannot be weaned from cardiopulmonary bypass with the aid of balloon counterpulsation and inotropic agents. Successful weaning from the centrifugal pump, however, depends on the careful selection of appropriate candidates as well as the strict control of pump flow, oncotic pressure, coagulopathy, blood pressure, and systemic afterload. The installation of a hemoconcentration device into the pump line helps control hemodilution and maintain adequate oncotic pressure. The management of a patient who was totally dependent upon left ventricular assistance is described.