Electrical characteristics of PbSe nanoparticle/Si heterojunctions.

I-V characteristics of PbSe nanoparticle/single crystal Si heterojunctions prepared by chemical bath deposition method show a rectifying behavior. With decrease in average PbSe grain size between 72 nm and 9 nm currents decrease for forward and reverse bias. C-V characteristics indicate that the junctions transform into that of a metal insulator semiconductor (MIS) as the PbSe nanoparticle size decreases from 72 nm to 9 nm. This insulator like behavior of the small PbSe nanoparticle films is attributed to the highly resistive grain boundaries. Cole-Cole plots demonstrate that on decrease of grain size, the grain boundary contribution increases and grain contribution to the overall impedance decreases. Frequency dependence of capacitance proves space charge polarization in larger grains, which recedes with decrease in average grain size proving insulator like behavior of small PbSe nanoparticles.

Some quality aspects of fish patties prepared from an Indian major carp, Labeo rohita (Ham.).

Six different types of fish patties were prepared from de-boned meat of three weight groups (250 500 g, 501-750 g, and 751-1,000 g) of an Indian major carp, Labeo rohita, using two extenders (boiled potato and corn flour). The weight of the fish and the type of the extender affected the nutritional quality of the patties. Cooking lowered the crude protein but increased the total lipid, total soluble sugars, and contents of the patties. Cooking yield increased with an increase in the weight of the fish. Similarly, the use of corn flour as the extender resulted in a higher cooking yield and higher fat retention capacity than boiled potato. The type of extender had no effect on the water-holding capacity of the patties. The weight of the fish and the extender had no significant effect on appearance, colour, flavour, taste, and the overall acceptability of the product. However, the patties prepared from 250-500 g and 501-750 g weight groups with corn flour as the extender had a significantly higher score for their texture. The total plate count suggested that the patties were safe (from microbiological point of view) up to a storage period of 80 days.

Influence of adsorption and diffusion rates on the growth of Pb1-x Fex S nanoparticle films.

We study the effect of adsorption rate on the particle size distribution in solution-grown ternary Pb1-x Fex S nanoparticle films. Computer simulations of a stochastic lattice model with adsorption and mass dependent diffusion have been performed to mimic the underlying mechanism of particle growth. The experimental as well as numerical data exhibit identical scaling with respect to the incident flux rate. A transmission electron microscope analysis of Pb1-x Fex S nanoparticle films reveals self-similarity in the particle size distributions corresponding to different adsorption rates as a manifestation of the observed scaling.

Aquacultural and socio-economic aspects of processing carps into some value-added products.

Carps are the mainstay of Indian aquaculture, contributing over 90% to the total fish production, which was estimated to be 1.77 million metric tonnes in 1996. Carp culture has a great potential for waste utilization and thus for pollution abatement. Many wastes such as cow, poultry, pig, duck, goat, and sheep excreta, biogas slurry, effluents from different kinds of factories/industries have been efficiently used for enhancing the productivity of natural food of carps and related species. Besides, several organic wastes/byproducts such as plant products, wastes from animal husbandry, and industrial by-products have been used as carp feed ingredients to lower the cost of supplementary feeding. However, to ensure the continued expansion of fish ponds and the pollution control, there must be a market for the fish (carps) produced in these ponds. The carps have, however, a low market value due to the presence of intra-muscular bones, which reduces their consumer acceptability. Thus, a need was felt to develop some boneless convenience products for enhancing the consumer acceptability of the carps. Efforts were made to prepare three value-added fish products, namely fish patty, fish finger and fish salad from carp flesh and were compared with a reference product ('fish pakoura'). Sensory evaluation of these products gave highly encouraging results. The methods of preparation of these products were transferred to some progressive farmers of the region who prepared and sold these products at very attractive prices. Carp processing has a great potential for the establishment of a fish ancillary industry and thus for boosting the production of these species. In Punjab alone, there is a potential of consuming 32,448 metric tonnes per annum of such value-added products (which would require 54,080 metric tonnes of raw fish). The development of value-added products has a significant role in raising the socio-economic status of the people associated with carp culture. The average cost of production of these products was estimated to be INR 80 per kg. With a sale price of INR 110 per kg, and a sale of 50 kg per day of the value-added products (26 days a month), the average monthly income of a carp-processing unit comes to be INR 39,000 (929 USD, approximately).

Clinical utility of human polymerized hemoglobin as a blood substitute after acute trauma and urgent surgery.

We have previously documented the safety of 1 unit (50 gram) of human polymerized hemoglobin (Poly SFH-P) in healthy volunteers. This report describes the first patient trial to assess the therapeutic benefit of Poly SFH-P in acute blood loss. Thirty-nine patients received 1 (n = 14), 2 (n = 2), 3 (n = 15), or 6 (n = 8) units of Poly SFH-P instead of red cells as part of their blood replacement after trauma and urgent surgery. There were no safety issues related to the infusion of Poly SFH-P. The plasma hemoglobin concentration ([Hb]) after the infusion of 6 units (300 gram) of Poly SFH-P was 4.8 +/- 0.8 g/dL (mean +/- SD). Although the red cell [Hb] fell to 2.9 +/- 1.2 g/dL, the total [Hb] was maintained at 7.5 +/- 1.2 g/dL. Poly SFH-P maintained total [Hb], despite the marked fall in red cell [Hb] due to blood loss. The utilization of O2 (extraction ratio) was 27 +/- 16% from the red cells and 37 +/- 13% from the Poly SFH-P. Twenty-three patients (59%) avoided allogeneic transfusions during the first 24 hours after blood loss. Poly SFH-P effectively loads and unloads O2 and maintains total hemoglobin in lieu of red cells after acute blood loss, thereby reducing allogeneic transfusions. Poly SFH-P seems to be a clinically useful blood substitute.

The development of hemoglobin solutions as red cell substitutes: hemoglobin solutions.

Although the efficacy of hemoglobin-based oxygen carriers was established more than 60 years ago, all prior clinical trials have demonstrated significant toxicity characterized by renal dysfunction, gastrointestinal distress, and systemic vasoconstriction. The mechanisms of these toxicities now appear to be understood. Tetrameric forms of the hemoglobin molecule extravasate from the circulation and interact with endothelial derived relaxing factor, leading to unopposed vasoconstriction. Although numerous efforts are underway to chemically modify the native tetramer, it is likely that all tetrameric forms of the hemoglobin molecule will continue to extravasate. We have focused on developing a polymerized form of hemoglobin that is virtually free of unreacted tetramer. The development and characterization of this polymerized pyridoxylated hemoglobin solution (Poly SFH-P) is described. Clinical trials have been completed successfully in volunteers, and are now underway to assess the safety and efficacy of Poly SFH-P as a clinically useful red cell substitute in the treatment of acute blood loss in the setting of trauma and surgery.

Hypovolemic shock.

This article defines a rational approach to the treatment of hemorrhagic shock. All patients that are hypovolemic following hemorrhage require fluid resuscitation. Some patients require red cell restoration and very few require correction of any clotting deficiencies. A physiologic approach to these problems will lead to optimal patient care in these circumstances.

Oxygen extraction ratio: a valid indicator of transfusion need in limited coronary vascular reserve?

We have described whole body oxygen (O2) extraction ratio (ER) as a reliable indicator of transfusion need in acute normovolemic anemia. In normal hearts, myocardial lactate production (-LACT), indicating anaerobic metabolism, does not occur until the ER greater than 50% and Hct less than 10%. It is not known if the ER is valid in the setting of limited coronary vascular reserve. This study assesses the effect of a critical left anterior descending (LAD) coronary stenosis on the compensation to acute blood loss anemia. Adult dogs were anesthetized, paralyzed, and mechanically ventilated. A critical LAD stenosis was created in seven animals (STEN). There were seven controls (CON). Animals underwent isovolemic exchange transfusion with 6% HES until cardiac failure (CF). Catheters were placed in the aorta, pulmonary artery, and anterior interventricular coronary vein. Cardiac failure occurred at Hct = 8.6% +/- 0.4% in the CON and 17.0% +/- 0.5% in the STEN animals. Cardiac output increased in the CON, but not in the STEN animals. Blood flow in the LAD increased in the CON but not the STEN animals. -LACT began in the CON and STEN animals at Hct less than 20% and coincided with an ER greater than 50% in both groups. We conclude that CF occurs at a higher hematocrit with a critical LAD stenosis. The whole body ER greater than 50% remains a valid indicator of myocardial metabolism in anemia in the presence of limited coronary vascular reserve. The ER may be a useful guide to transfusion therapy.

Artificial blood: current status of hemoglobin solutions.

Attempts to develop a hemoglobin-based red cell substitute have spanned many decades, but no clinically useful product has been produced to date. The issues preventing clinical application primarily are ones of safety--not efficacy. Numerous animal studies have documented the efficacy of SFH. Although effective, the solution has limitations that have caused concern. Oncotic considerations limit the concentration of the infusate SFH to 6 to 8 g/dL, or half-normal. Owing to the loss of organic phosphate modulators of P50, such as 2,3-DPG, the P50 of SFH is typically between 12 and 14 mm Hg, which is also half the normal value. And finally, the intravascular half-life of SFH is too short, ranging only from 2 to 6 hr. Polymerization provides a means of correcting these limitations. The high oxygen affinity can be greatly diminished by covalent binding of pyridoxal-5'-phosphate to the N-terminal of the chains. Colloid osmotic pressure exerted by a protein solution is proportional to the number of discrete colloid particles. Through polymerization, the number of colloid particles is reduced, leading to a decrease in COP. Data show that this can be achieved in a reproducible fashion. The rate at which COP diminishes determines the yield of polymeric species, as well as their molecular weight distribution. Polymerization can be controlled to result in a yield of 75% to 85% polymers with a molecular weight distribution of 128 to 400 kd. The number average and the weight average molecular weights indicate that the large proportion of polymers represent the cross linking of two tetramers. The data that reflect the interaction of oxygen with poly-SFH-P indicate that the oxygen carrying function of hemoglobin has not been significantly altered by the chemical modifications. The binding coefficient of oxygen is unchanged. As anticipated, there is a loss of cooperativity (diminished Hill coefficient) between the hemoglobin chains, suggesting structural restrictions in the polymeric species because of cross linking. A reduced alkaline Bohr effect is the expected result, and data confirm this. Finally, some increase in oxygen affinity is to be expected with polymerization. This is indeed the case, although the P50 of poly-SFH-P is comparable to banked blood (18 to 22 mm Hg). To be clinically useful, a modified hemoglobin solution requires a reasonable shelf-life.(ABSTRACT TRUNCATED AT 400 WORDS)

Accelerated erythropoiesis: the hidden benefit of autologous donation.

The risks associated with the administration of blood products have increased efforts to avoid homologous transfusions. Preoperative autologous donation has received renewed interest as a method of decreasing homologous transfusion requirements. Autologous donations may also stimulate postoperative erythropoiesis. The purpose of this study is to evaluate the effect of an aggressive autologous donation program on postoperative erythropoiesis. Ten adult male baboons were divided into two groups. The autologous group (n = 5) donated an average of 2 units of blood per week for 5 weeks before operation. The control group (n = 5) had no preoperative treatment. All animals then underwent a laparotomy and exchange transfusion with hetastarch to a final hematocrit of 15 percent. The time required to recover to hematocrits of 20 percent (3.3 vs. 5.7 days, p less than 0.01), 25 percent (7.0 vs. 8.8 days, p less than 0.05), and 30 percent (11.1 vs. 17.7 days, p less than 0.01) was shorter in the autologous group. The autologous group had more intense reticulocytosis during the first 4 postoperative days (p less than 0.03). The data show that participation in an aggressive autologous donation program improves the erythropoietic response to anemia in the postoperative setting. This represents a hidden benefit of preoperative autologous donations and suggests that more aggressive donation schedules may be clinically beneficial. Recognition of that acceleration of erythropoiesis by autologous donation could further reduce the need for transfusion of homologous blood.

New dimensions to poliomyelitis.

About 22% of persons who suffer from acute paralytic poliomyelitis 20 to 30 years ago and were fully rehabilitated with maximal functional recovery began to experience new symptoms termed "Post-polio Sequelae" (PPS). These include unaccustomed fatigue, weakness in muscles previously affected or apparently unaffected, new joint pains, respiratory difficulties and intolerance to cold. Predictors for PPS are development of acute attack of paralytic polio before 10 years of age, involvement of all four limbs and having needed a ventilator during acute stage. The functional decompensation in PPS is presumed to be due to loss of normal neurones by aging and by metabolic fatigue of stressed neurones over passing years. Joint deformities due to muscular imbalance are also responsible for some of the symptoms. Treatment consists of reassurance and use of assistive devices and assistive exercises. The extent of problem of PPS is not known in India.

The efficacy of polymerized pyridoxylated hemoglobin solution as an O2 carrier.

A polymerized pyridoxylated hemoglobin solution (Poly SFH-P) has been prepared with a normal [Hb] of 14 g/dL, a normal COP of 20 to 25 torr, a P50 of 16 to 20 torr, and a plasma T1/2 of 40 to 46 hours. Animals underwent a total exchange transfusion with Poly SFH-P to assess its ability to support hemodynamics and oxygen transport in the absence of red cells. All animals survived the exchange transfusion. Mean arterial pressure (MAP), heart rate (HR), cardiac output (CO), and oxygen consumption (VO2) remained at baseline values at zero hematocrit after the exchange. The final plasma [Hb] at Hct less than 1% was 9.7 +/- 0.4 g/dL. These results are significantly better than previous data with unmodified tetrameric hemoglobin solution (SFH). Poly SFH-P supports life in the absence of red cells. In contrast to SFH, Poly SFH-P achieves a nearly normal [Hb], a longer T1/2, and maintains baseline hemodynamics and oxygen consumption at zero hematocrit. These results document that Poly SFH-P is an effective oxygen carrier that offers greater potential than previous products as a clinically useful red cell substitute.

Effect of hemoglobin solution on compensation to anemia in the erythrocyte-free primate.

Hemoglobin solutions are undergoing clinical trials as erythrocyte substitutes. Some of these solutions have higher O2 affinities compared with normal erythrocyte hemoglobin. Also, they appear to interact with endothelial-derived smooth muscle relaxation. The purpose of this study was to evaluate the nature and limits of compensation to acute normovolemic anemia in the erythrocyte-free primate maintained with a hemoglobin solution. The experimental group consisted of six anesthetized paralyzed adult baboons (Papio anubis) that were exchange transfused (ET) with a pyridoxylated polymerized hemoglobin solution [hemoglobin concentration [( Hb]) = 14 g/dl, O2 half-saturation pressure of hemoglobin (P50) = 19.6 Torr] until a hematocrit less than 1% was achieved. They underwent a second ET with Dextran-70 until [Hb] = 1 g/dl. A control group (n = 6) underwent an ET with Dextran-70 until [Hb] = 1 g/dl. Both groups maintained O2 consumption (VO2) until [Hb] = 3 g/dl. Both groups were stable until [Hb] less than 1 g/dl, and both groups increased their cardiac output. The relation between VO2 and O2 delivery was similar for both groups. In vivo P50 and mixed venous O2 tension were significantly lower in the experimental group. The nature and limits of compensation to diminished O2 delivery due to anemia were similar in the two groups.

Erythropoietic response to acute anemia.

Reliance on a brisk erythropoietic response to untreated blood loss is an alternative to transfusion of homologous blood. Slow erythropoiesis has been observed in ICU patients who refused blood. Many of these patients received supplemental oxygen therapy and Fluosol-DA, a temporary red cell substitute. This study reports the erythropoietic response, in the baboon, to moderate (Hct 20%) and severe (Hct 10%) anemia. In addition, the effect of oxygen therapy (FIO2 0.6 for 1 wk) and fluorocarbon emulsions (Oxypherol) on erythropoiesis was evaluated. Baboons uniformly survived acute normovolemic anemia with Hct 10%. In all cases, the response to anemia was characterized by a lag period (with no change in Hct), and a nonlinear recovery period. A lag period of 3 days was observed in both moderate and severe anemia for baboons breathing room air or FIO2 0.6. The lag period was prolonged to 1 wk in the presence of Oxypherol. The recovery period exhibited a uniform and negative correlation between the rate of Hct change and the Hct, in all cases. The theoretical maximum rate of increase of Hct was 2.6%/day. In untreated blood loss, shortening the lag period and increasing the slope of the recovery period will decrease the length of time that the patient is anemic.

Physiologic effects of acute anemia: implications for a reduced transfusion trigger.

The risks of transfusion-associated infectious disease have led to a reassessment of transfusion practice, which in turn has resulted in a trend toward the reduction of homologous transfusion. This reduction is primarily due to the initiation of hemotherapy at more severe levels of anemia. The optimum threshold for the initiation of transfusion therapy, or the transfusion trigger (TT), is unknown. The purpose of this study is to evaluate the effects of withholding transfusion or lowering the TT to a hematocrit (Hct) of 15 percent in unanesthetized animals. Nineteen adult baboons underwent a laparotomy to simulate surgical stress. Upon their recovery from anesthesia, hemodynamic measurements were obtained, and the animals underwent an exchange transfusion (ET) with 6-percent hetastarch to a final Hct of 15 percent. After ET, hemodynamic measurements were repeated, and the animals were followed for 2 months. There was no morbidity after ET or during the 2-month observation period. After ET, there was a significant increase in both the cardiac output (3.3 vs. 2.5 L/min, p less than 0.001) and the oxygen extraction ratio (59.9 vs. 38.2%, p less than 0.0001). Oxygen delivery fell after ET (18.9 vs. 11.1 cc/kg/min, p less than 0.001), but there was no significant change in oxygen consumption after ET. The unanesthetized animals adapted well to severe anemia and experienced no adverse effects on their long-term survival in this setting, which suggests that the reduction of the TT to a Hct of 15 percent in normal animals is safe. Adoption of this TT could result in a significant reduction in the requirements for homologous transfusion with its attendant risks.

Perioperative recombinant human erythropoietin.

The risks of transfusion-associated infectious disease have made increased efforts to avoid homologous transfusion imperative. Little attention has been focused on efforts to accelerate erythropoiesis as a method of reducing homologous blood use. Recombinant human erythropoietin (rHuEPO) has been shown to enhance erythropoiesis. The purpose of this study was to evaluate the effects of perioperative rHuEPO administration on postoperative erythropoiesis. Fifteen baboons were divided into three groups of five each. Group I received no rHuEPO. Group II received five daily preoperative doses of rHuEPO (1000 U/kg). Group III received five daily preoperative doses and 14 daily postoperative doses of rHuEPO (1000 U/kg). All animals underwent a laparotomy followed by an exchange transfusion to a final hematocrit of 15%. The time in days required to recover to hematocrits of 20% was significantly shorter in both groups that received preoperative doses of rHuEPO when compared with that of controls (3.3 vs 5.7 days, p less than 0.01). The recovery times to hematocrits of 25%, 30%, and baseline levels were all significantly shorter in the group that received both preoperative and postoperative doses of rHuEPO. The data show that perioperative dosage of rHuEPO significantly accelerates postoperative erythropoiesis. Perioperative administration of rHuEPO may reduce the requirements for homologous transfusion.

Treatment of acute postoperative anemia with recombinant human erythropoietin.

Risks inherent in the administration of blood products have increased efforts to avoid homologous transfusion. Although this has increased interest in autologous transfusion and intraoperative salvage, little attention has been focused on efforts to enhance endogenous erythropoiesis as a method of minimizing exposure to homologous blood. Recombinant human erythropoietin (rHuEPO) has been shown to enhance erythropoiesis. The purpose of this study is to evaluate the effect of rHuEPO, administered postoperatively, on a model of acute blood loss. Eleven adult male baboons were randomized into two groups. All animals underwent a laparotomy and an exchange transfusion, with 6% hetastarch, to a final hematocrit of 15%. Group I (N = 6) received 1,000 units/kg of recombinant human erythropoietin daily for the first 14 postoperative days. Group II (N = 5) received an equivalent volume of placebo. All animals were given supplemental vitamin B12, folate and 200% of shed iron, as iron dextran IV, after exchange transfusion. Response was observed for a period of 35 days. All animals survived the protocol. There were no adverse reactions to rHuEPO or surgical complications. The hematocrits were similar between groups at baseline and after exchange transfusion. The maximal rate of erythropoiesis was significantly faster in the rHuEPO group (2.1 vs. 1.3%/day; p less than 0.01). The time required to return to hematocrits of 30% (9.9 vs. 17.4 days, p less than 0.001) and to baseline hematocrits (11.9 vs. 32.1 days, p less than 0.01) were both significantly shorter in the rHuEPO group. The data show that rHuEPO accelerates the recovery from anemia in the postoperative setting. Acceleration of erythropoiesis represents another alternative to homologous transfusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Recombinant human erythropoietin and autologous blood donation.

Risks of transfusion are minimized with autologous blood. However, autologous donation programs require 2 to 5 weeks to yield only 2.2 units per patient. Recombinant human erythropoietin (r-HuEPO) has been shown to increase erythropoiesis. This study evaluated the effects of r-HuEPO on an aggressive autologous donation program. Twelve adult male baboons were randomized into two groups of six. All animals were studied three times per week for 5 weeks. A unit of blood was donated when on any study day the hematocrit was greater than 30%. Animals received intravenously either 750 units/kg of r-HuEPO (n = 6) or placebo (n = 6) on each study day. Iron dextran was given intravenously to replace 150% of shed iron. The r-HuEPO group had an earlier onset of reticulocytosis (2.7 vs 5.5 days, p less than 0.01) and donated 35% more blood (13.5 vs 10.0 units, p = 0.01) than the control group. No adverse reactions to r-HuEPO were observed. The data show that an aggressive autologous donation program can yield 10 units of blood over a 5-week period. Further, r-HuEPO increases that yield by an additional 35%. This aggressive autologous donation program with r-HuEPO may significantly reduce the need for homologous transfusion and its attendant risks.

Limits of cardiac compensation in anemic baboons.

The risk of homologous blood may cause physicians to withhold red cell treatment after acute blood loss. We believe that in the euvolemic patient with acute anemia, the heart is the principal organ at risk. The cardiac compensation to extreme anemia is unknown and is the purpose of this report. Fourteen adult baboons were anesthetized, paralyzed, and ventilated with room air. Left atrial and coronary sinus catheters were inserted surgically. Experimental animals (n = 7) were hemodiluted at constant left atrial pressure with 5% human serum albumin. Control animals (n = 7) underwent similar volume exchanges with fresh, cross-matched, homologous red blood cells resuspended in human serum albumin, also at constant left atrial pressure. Six of seven experimental animals survived until hematocrit levels were 4%. Adequate cardiac compensation was observed until hematocrit levels were less than 10%. Increased flow, without increases in the O2 extraction ratio, was the mechanism of compensation used by the healthy heart with patent coronary vessels.