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Objective: Umbilical cord blood is an effective alternative to bone marrow as a source of hematopoietic stem cells in transplantation. However, the amount of donor blood and the cell content that are collected may be insufficient for engraftment in some adult recipients. This study identifies obstetric factors that affect retrievable placental cord blood volume. Study design: A retrospective analysis of factors that were obtained by direct observation or medical record review that were related to harvested cord blood volume was conducted; the analysis involved 9205 deliveries from mothers who donated placental cord blood through the obstetric services of two New York City hospitals between 1993 and 1999. Results: Obstetric factors that influenced significantly the total volume of blood that was collected were route of delivery, induction of labor, presence of a nuchal cord, infant birth weight, multiple births, placental weight, and duration of labor. The length of the umbilical cord from the venipuncture site and the length of time to cord blood collection also affected the volume that was retrieved. Maternal ethnicity was associated with cord blood yield; Caucasian mothers provided larger quantities than either African American or Asian mothers. Conclusion: Our results confirm that the volume of residual placental cord blood that is collected for hematopoietic stem cell transplantation is influenced by several factors, the presence of which predict the likelihood of an adequate collection. Collected volumes can be improved when a longer length of the cord is left with the placenta and when there is a shorter time between the delivery of the placenta and the collection. (Am J Obstet Gynecol 2003;188:503-9.)

With the promise of nonvolatility, practically infinite write endurance, and short read and write times, magnetic tunnel junction magnetic random access memory could become a future mainstream memory technology.

We demonstrate a packaging system/test probe suitable for testing complex, large scale superconducting integrated circuits with thousands of Josephson junctions. The cryopackage is designed to work with a 1 cm superconducting die, with liquid He immersion cooling using a standard storage dewar. The package has 80 high-speed input-output lines (DC to 20 GHz) which connect the chip to room temperature electronics. The tip of the cryopackage, containing the chip, is shielded from the ambient magnetic field with two mumetal cylinders and contains a built-in coil, which provides in-situ degaussing of the inner shield. To clear flux trapped in the chip being tested, the probe contains a novel gas manifold and a system of heaters. During the defluxing operation, a heater evaporates liquid helium inside the chip enclosure, the expanding vapor purging the liquid from the sample cell and warming the chip above its transition temperature. Once the chip is defluxed, the liquid helium is allowed back into the cell, at a rate slow enough to avoid trapping flux in the chip while it is cooled. The process can be automated and does not require any movement of the probe once inserted in the dewar.

The primary voltage standard system based on the Josephson junction array (JJA) produces the ultimate in accuracy for dc voltage calibration. However, it is only used in the highest level standards laboratories due to the expense and inconvenience of liquid helium cooling. In cooperation with the US Army Research Laboratory, HYPRES has developed a mobile JJA primary voltage standard system using a closed cycle refrigerator (CCR). The system performance is comparable to a conventional liquid helium system. The elimination of liquid helium makes the mobile system not only more economically attractive, but also more convenient to use. The mobile JJA voltage standard system is very suitable for users who lack screw to liquid helium, and for those who require transportability.

Objective The present study developed and evaluated a practical teaching model and training protocol for Word catheter placement in the treatment of a Bartholin gland cyst. Study design Residents were asked to treat a model of the female perineum, fashioned from harvested porcine tissue, with a simulated Bartholin cyst via Word catheter placement and drainage. Each resident was evaluated for procedural competence. They were retested after the viewing of a continuous 59-second video demonstrating catheter placement. Results The model's resemblance to female genitalia was confirmed by 68% of residents. Correct diagnosis and treatment of a Bartholin gland cyst was made by 61%. The mean pretraining score was 5.5 ± 1.46, while the post-training average was 8.2 ± 1.20, indicating an approximate 58% increase in resident proficiency (P Conclusion A model of the female perineum fashioned from harvested porcine tissue is a suitable instructional aid in the recognition and treatment of a Bartholin cyst. Proficiency in Word catheter placement is improved through the use of the model and instructional video.

Background. Although biological glues have been used clinically in cardiovascular operations, there are no comprehensive comparative studies to help clinicians select one glue over another. In this study we determined the efficacy in controlling suture line and surface bleeding and the biophysical properties of cryoprecipitate glue, two-component fibrin sealant, and "French" glue containing gelatin-resorcinol-formaldehyde-glutaraldehyde (GRFG). Methods. Twenty-four dogs underwent a standardized atriotomy and aortotomy; the incisions were closed with interrupted 3-0 polypropylene sutures placed 3 mm apart. All dogs had a 3- by 3-cm area of the anterior wall of the right ventricle abraded until bleeding occurred. The animals were randomly allocated into four groups: in group 1 (n = 6) bleeding from the suture lines and from the epicardium was treated with cryoprecipitate glue; in group 2 (n = 6) bleeding was treated with two-component fibrin sealant; group 3 (n = 6) was treated with GRFG glue; group 4 (n = 6) was the untreated control group. The glues were also evaluated with regard to histomorphology, tensile strength, and virology. Results. The cryoprecipitate glue and the two-component fibrin sealant glue were equally effective in controlling bleeding from the aortic and atrial suture lines. Although the GRFG glue slowed bleeding significantly at both sites compared to baseline, it did not provide total control. The control group required additional sutures to control bleeding. The cryoprecipitate glue and the two-component fibrin sealant provided a satisfactory clot in 3 to 4 seconds on the epicardium, whereas the GRFG glue generated a poor clot. There were minimal adhesions in the subpericardial space in the cryoprecipitate and the two-component fibrin sealant groups, whereas moderate-to-dense adhesions were present in the GRFG glue group at 6 weeks. The two-component fibrin sealant was completely reabsorbed by 10 days, but cryoprecipitate and GRFG glues were still present. On histologic examination, both fibrin glues exhibited minimal tissue reaction; in contrast, extensive fibroblastic proliferation was caused by the GRFG glue. The two-component and GRFG glues had outstanding adhesive property; in contrast, the cryoprecipitate glue did not show any adhesive power. The GRFG glue had a significantly greater tensile strength than the two-component fibrin sealant. Random samples from both cryoprecipitate and the two-component fibrin glue were free of hepatitis and retrovirus. Conclusions. The GRFG glue should be used as a tissue reinforcer; the two-component fibrin sealer is preferable when hemostatic action must be accompanied with mechanical barrier; and finally, the cryoprecipitate glue can be used when hemostatic action is the only requirement.

Paraplegia as a consequence of spinal cord ischemia associated with procedures on the thoracic and thoracoabdominai aorta has been linked to the interaction of proximal hypertension with elevated cerebrospinal fluid pressure (CSFP) during aortic cross-clamping (AXC). CSFP reduction via cerebrospinal fluid (CSF) drainage is thought to significantly prolong the cord's tolerance to AXC. Likewise, partial exsanguination is reported to effectively reduce ischemic injury by controlling proximal hypertension. To evaluate the individual and collective efficacy of both techniques, 18 mongrel dogs (25 to 35 kg), divided into three equal groups, underwent a fourth interspace left thoracotomy AXC. Baseline proximal arterial blood pressure (PABP), distal arterial blood pressure (DABP), and CSFP were established and monitored at 5-minute intervals during 120 minutes of AXC, and for 30 minutes thereafter. Group I animals were partially exsanguinated prior to AXC to maintain PABP at a mean of 115 to 120 mmHg. Group II animals had sufficient (16 ± 5 cc) CSF withdrawn to maintain a DABP-CSFP gradient, i.e., spinal cord perfusion pressure (SCPP) of 20 mmHg. Group III animals were treated with both CSF drainage and partial exsanguination in the same manner as groups I and II, respectively. Periop-erative somatosensory evoked potential (SEP) monitoring evaluated cord function. Postoperative neurological outcome was assessed with Tariov's criteria. SEPs degenerated approximately 22 minutes following AXC for groups II and III. In contrast, group I exhibited rapid (10 ± 7 min) SEP loss. All five surviving group I animals displayed paralysis 48 hours postopera-tively. Mean PABP was significantly higher in group II (155 ±18 mmHg) than in either group 1 (117 ± 9 mmHg) or Ill (120 ± 14 mmHg) (p < 0.001). CSFP was significantly higher in group I (14 ± 4 mmHg) than in either group II or III (5 ± 2 mmHg) (p < 0.0001). The only parameter associated with neurological injury was low SCPP, which inversely correlated with CSF dynamics. Group I animals, with a mean SCPP of 4.6 mmHg, exhibited paraplegia, while groups II and Ill, with SCPP values above 20 mmHg, were free of neurological injury. Proximal hypertension did not play a role in cord injury. This study underscores the potential of CSF drainage to protect the ischemic spinal cord. (J Card Surg 7994;9:637–637)

Background: We report here the results of combined coronary artery bypass grafting (CABG) and abdominal aortic aneurysm (AAA) repair and the factors associated with higher mortality following this procedure. Methods: The authors performed a retrospective chart review of 26 patients who underwent combined CABG and AAA repair between March 1990 and October 1996. Results: No postoperative myocardial infarction or major cardiac complications were noted. A morbidity rate of 38% (n = 10) and mortality rate of 11% (n = 3) were noted. Comparative analysis of nonsurvivors (n = 3) versus survivors (n = 23) revealed the following: ejection fraction (EF) was significantly lower (33% ± 3% versus 44% ± 14%, P

We have reported previously (Pong-Fei Lu et al., 2004) a low-swing latch (LSL) with superior performance-power tradeoff compared to the conventional pass-gate master-slave latch. In this paper, hardware results are presented for the proposed LSL with pulsed clock waveforms. The motivation is to combine low-voltage swing with pulsed signals to further reduce overall system power in high-frequency microprocessors. We have designed a 65-bit accumulator loop experiment to mimic a microprocessor pipeline stage. The local clock buffer design features a mode switch to toggle between two-phase (c1/c2) master-slave clocking and one-phase pulsed (c2 only) clocking. Our data show that 15-25% system power saving can be achieved in pulsed mode compared to non-pulsed mode. Power contribution from individual components is also presented

We report A new low-swing latch (LSL) for low-power applications. Unlike the conventional transmission gate latch, the LSL allows reduced voltage on the clock inputs. Therefore the local clock buffer (LCB) can use reduced swing to save power while all other circuits are running at nominal voltage. We have implemented an accumulator loop experiment in an early version of IBM's 90 nm SOI technology on a testchip. The experiment consists of an adder and a decrementer surrounded by latches to mimic logic between pipeline stages. Side-by-side comparisons between the transmission gate latch and LSL are designed to illustrate the superior power-performance tradeoff of the LSL approach. Hardware measurements have shown 12% AC power saving in 90 nm technology.

Wound-related morbidity frequently encountered after open-incision harvesting of vessel conduits for coronary artery bypass grafting (CABG) is invariably recognized as an obstacle impeding the patient's path towards complete postoperative recovery. The endoscopic approach provides surgical access to the intended conduit vessel while affording an appreciably lower incidence of traumatic injury to the surrounding tissues. For this reason, the minimally invasive endoscopic dissection of vessel conduits is steadily gaining acceptance as a preferable alternative to the standard open-incision technique. Endoscopic systems, originally developed for general surgical procedures in the early 1990s, and readily adapted to saphenous vein harvesting by mid-decade, are now also being applied to minimally invasive radial artery harvesting. The growth of this surgical modality has paralleled the rapid development of remote access minimally invasive endoscopic devices and technologies and therefore remains an evolving body of knowledge. As experience and refinements in instrumentation progress, the endoscopic approach will undoubtedly become the procedure of choice for harvesting vessel conduits. This article provides a practical primer, based on the benefit of our serial experience with endoscopic vein and radial artery dissections, for those considering the minimally invasive endoscopic approach in harvesting vessels for CABG.

Surgical repair of traumatic lesions or aneurysmectomy of the descending thoracic aorta necessitates the interruption of distal aortic blood flow, a situation which invariably promotes proximal hypertension accompanied by a precipitous increase in cerebrospinal fluid pressure and distal hypoperfusion. All are significant determinants of postoperative paraplegia. The institution of aortic bypass, distal to cross-clamping, by either implantation of an extraluminal passive shunt or deployment of left atrial to femoral artery (LA-FA) cannulation with a centrifugal pump, is the most widespread modality to afford a means of proximal decompression and provide distal perfusion. Passive shunt techniques do not consistently provide optimal bypass efficiency, due to inherent limitations of device design and the inability to accurately monitor and control flow. The LA-FA bypass technique is superior to passive shunts in effecting proximal unloading by allowing for precise adjustment of blood flow to equilibrate proximal and distal aortic pressures. The concomitant use of cerebrospinal fluid drainage with LA-FA bypass can effectively reduce the incidence of postoperative paraplegia. Intraoperative monitoring of evoked potentials as a sensitive indicator of spinal cord ischemia should be considered an integral component of preserving cord function. The use of cerebrospinal fluid drainage and evoked potential monitoring in conjunction with LA-FA bypass is therefore highly advisable.

The acute interruption of blood supply to the spinal cord during thoracic and thoracoabdominal aortic reconstructions, if unabated, inevitably causes neurological injury secondary to regional hypoxia. Techniques that address the multifactorial nature of spinal cord ischemic injury have evolved to preserve neuromotor function. However, the overall incongruity of the spinal cord's vascular anatomy makes it virtually impossible to predict, with any degree of certainty, the duration of aortic cross-clamping (AXC) that can safely be endured. The sensitivity of evoked potential monitoring to the disruption of spinal cord perfusion has led to the emergence of this modality as an effective tool at the surgeon's disposal for the intraoperative assessment of distal aortic perfusion and cord viability during proximal AXC. Somatosensory evoked potentials (SSEP) provide invaluable diagnostic data as to the status of cord function, through the continuous appraisal of signal amplitude and latency. A latency increase, as small as 10% of the pre-AXC value, is linked to a reduction of spinal cord perfusion pressure and thereby associated with a high incidence of neurological impairment. Four discrete types of SSEP responses have been identified to represent differing surgical scenarios during AXC. The Type I response (deterioration of SSEP within 3 to 5 minutes) is indicative of a failure to maintain a distal pressure of at least 60 mm Hg, whereas a Type II signifies adequate distal aortic perfusion. Sudden loss of signal as witnessed in a Type III SSEP implies compromised critical intercostal vessels and indicates their expeditious reimplantation. A gradual (30 to 50 minutes) SSEP "fadeout" corresponds to marginal distal perfusion, suggesting the presence of extensive pathology. Intraoperative evoked potential monitoring, in conjunction with distal aortic perfusion, permits rapid identification and correction of compromised spinal cord blood flow, permitting repair of aortic lesions without the added liability of time constraints.

Immediate neurological deficits as a complication of aortic surgery occur as the direct result of hypoxia, related to the acute deprivation of spinal cord blood supply inflicted by prolonged aortic cross-clamping (AXC). The etiology of spinal cord ischemia constitutes a series of progressive interdependent events which include proximal hypertension, increase in cerebrospinal fluid pressure, perioperative hypotension, inadequate perfusion to critical intercostal or lumbar vessels, extent of aortic pathology and duration of AXC. Several intraoperative interventions and strategies, which address the multifactorial nature of cord injury, are presented by the authors. Of critical importance is the role of adequate distal aortic perfusion, with either left atrium-femoral artery (LA-FA) bypass or arterial-arterial passive shunts, to control both central hypertension, through proximal unloading, and hypotension distal to AXC. Equally crucial is the increase in CSF pressure, secondary to proximal hypertension, which acts antagonistically to distal aortic pressure in regulating spinal cord perfusion pressure (SCPP). Cerebrospinal fluid drainage (CSFD) reduces CSF pressure to offset SCPP to favor cord perfusion. Pharmacological agents, such as papaverine and steroids in combination with CSFD, produce a synergistic benefit of extending the time interval of safe AXC. Encouraging results have also been realized with circulatory arrest and profound hypothermia which reduce oxygen demand of neural tissues and extend the safe duration of AXC interval. The use of distal bypass is most effective with CSFD as an integral component of a multimodality approach, which also incorporates the intraoperative monitoring of somatosensory evoked potentials (SSEP), to detect the onset of spinal cord ischemia and assess the adequacy of distal aortic perfusion and disposition of critical segmental vessels.

Superconducting Quantum Interference Devices (SQUIDs) that operate at 77 K have now been fabricated by many groups from high temperature superconductors. We will examine the performance of high-Tc SQUIDs, including the issues of the periodicity and hysteresis of the response, the magnitude of the noise in the SQUIDs, and the manufacturability of the devices. The nature of the junctions forming the SQUIDs, which have been naturally occurring grain boundaries in all but a few of the reported devices, and the physical mechanisms responsible for the noise sources will also be reviewed. The possible applications of these and future high-Tc SQUIDs will be examined.

Internal mammary artery (IMA) bypass grafting to the anterior descending coronary artery was performed in 2,100 patients between January 1978 and July 1986. The average number of additional saphenous vein grafts (SVGs) per patient was 1.8. During the same period, 1,753 patients underwent coronary artery bypass grafting using an SVG (average number of grafts per patient, 3.2). The average patient age was similar: 62.3 years for IMA grafts and 64.7 years for SVGs. Men constituted two thirds of each group. Left ventricular function was impaired (ejection fraction less than 45%) in 1,071 (51%) of IMA grafts and 847 (48.3%) of SVGs. Other aggregate risk factors, ie, elevated blood pressure, diabetes mellitus, previous myocardial infarction, and congestive heart failure, were similar in each group. Operative results and postoperative mortality of the IMA and SVG patients were comparable. However, the long-term probability of cumulative survival and occlusion-free survival were significantly greater and the probability of recurrent angina and reoperative coronary artery bypass grafting were significantly less in IMA graft patients (p less than 0.015). The relative risk of occlusion in an SVG was 4 to 5 times greater than that of the IMA graft. These data indicate that a patent IMA graft to the anterior descending coronary artery protects against recurrent angina and death from cardiac-related causes, and that the IMA should be the conduit of choice.

We compared the mechanical integrity of microvascular anastomoses created with a carbon dioxide (CO2) laser with conventional suture anastomoses. Seventy rat femoral artery segments (35 lased and 35 sutured) were harvested at 1, 24, and 72 hours, and 1, 3, 6, and 12 weeks postoperatively. These segments were subjected to increasingly higher in vitro intraluminal hydrostatic pressures (bursting pressure). Conventionally sutured anastomoses exhibited significantly increased ability (p less than 0.05) to withstand greater bursting pressures than the laser-welded tissue up to 3 weeks postoperatively. After the third postoperative week, the laser anastomoses demonstrated increased bursting pressures compared with the conventional anastomoses. At the end of the 12-week period both groups demonstrated an ability to withstand supraphysiologic pressures in excess of 2000 mm Hg.

This experiment evaluated the influence of blood on the weld strength of laser-assisted microvascular anastomoses (LAMA). Rat femoral arteries were anastomosed end-to-end by either direct laser welding (group I) or by a blood-bonded technique (group II) whereby fresh blood was applied to the vessel edges before laser exposure. Bursting strength was measured at 0, 1, and 24 hours and at 3 and 7 days by infusing methylene blue into the vessel while pressure was monitored. The results showed significantly increased bursting strength in group II compared with group I at 0 hour and 7 days (P less than 0.05). There was a significant increase in bursting strength in group I from 0 hour to 1 hour (P less than 0.05). It is concluded that blood-bonding enhances the early bursting strength of LAMAs and may facilitate arterial wall healing.