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)     

Immunogenicity of deglycosylated zona pellucida antigens and their inhibitory effects on fertility in rabbits.

Influence of carbohydrates on the immunogenicity and immunocontraceptive potential of zona pellucida glycoproteins has been investigated in rabbits. Porcine zonae pellucidae, following deglycosylation with trifluoromethane-sulfonic acid, retained significant immunogenic potential, as shown by the ability to generate antibodies which cross-reacted with the heterologous antigen. Antibody response, however, was much stronger against the native zona glycoproteins, thereby suggesting that both carbohydrate and protein moieties contribute to the overall immunogenicity of the zona pellucida antigens. Contraceptive efficacy of active immunization with the deglycosylated zona antigens, when evaluated by mating experiments, demonstrated inhibition of fertility in all immunized rabbits. Normal ovarian functions were disrupted in these animals, as revealed by the reduction in ovarian weights and gross impairment of folliculogenesis. Flushing of the oviducts of the immunized animals yielded a markedly reduced number of ova ovulated in response to hCG administration, none of which were fertilizable. Results collectively suggest that active heteroimmunization with deglycosylated zona pellucida antigens is effective in reducing fertility in rabbits.     

The relationship of serum IL-6 levels to acute graft-versus-host disease and hepatorenal disease after human bone marrow transplantation.

The potential involvement of cytokines in acute graft-versus-host disease led us to analyze interleukin-6 in serial serum sets from 22 allogeneic marrow recipients who developed either grade 3 or 4 GVHD (n = 10), grade 2 GVHD (n = 6), or grade 1 or no diagnosed GVHD (n = 6). A total of 279 serial serum samples taken three times weekly before day 35 were analyzed. Maximum IL-6 levels were greater than 40 U/ml (range, 40-1536 U/ml), 11-40 U/ml, and less than or equal to 10 U/ml for six, eleven, and five patients, respectively. Serum IL-6 peaks were temporally related to onset of GVHD, onset of a syndrome of hepatorenal dysfunction (HRD), or bilateral lung infiltration. Eight of ten patients who developed grade 3 or 4 GVHD overall had IL-6 maxima of greater than 10 U/ml an average of 1.5 +/- 1.8 days before the clinical onset. Fifteen of 17 patients with peak IL-6 levels greater than 10 U/ml developed symptoms of hepatic and renal dysfunction within three days of the peak, while none of five patients with less than or equal to 10 U/ml of Il-6 developed HRD. Regression analysis demonstrated a linkage between the log magnitudes of the serum IL-6 peaks and onset of either GVHD or HRD within three days (P = 0.001). Furthermore, IL-6 peaks tended to precede GVHD onset for the 10 patients whose GVHD onset and IL-6 peak were within three days of each other (P = 0.02). These results, confirmed by both specific bioassay and by IL-6 ELISA, support the idea that acute GVHD in humans involves a cytokine cascade that includes production of IL-6 in addition to the previously reported involvement of tumor necrosis factor alpha and interferon-gamma.     

Experimental investigation of the implementation of Fermi-Eyges-Hogstrom electron beam model of the Pinnacle3 system at extended SSDs.

A commercially available ADAC Pinnacle(3) radiation treatment planning system has been used to model electron beams from a Varian Clinac 2300C/D in the energy range of 6 to 22 MeV. Prior to clinical use, the dosimetric characteristics of the beams have to be modeled accurately. As a first step for beam modeling, a number of dose profile and depth dose measurements were taken at standard source-to-surface distance (SSD) of 100 cm. Dose profiles and depth dose measurements at extended SSDs up to 120 cm are important for ascertaining accuracy of the model, as well as their clinical usefulness in the treatment of some sites (e.g., head-and-neck tumors). Modeled and measured beam data were compared. Over 98% of comparison points (modeled vs. measured) at 100-cm SSD were within 2.5% or 2.5 mm. At 110 cm SSD, over 98% of compared points were within 4% or 4 mm, and at 120-cm SSD, over 98% of compared points were within 5% or 5 mm. Overall, more than 98% of compared points were within 4% or 4 mm. Better models were produced for lower energies (6 to 15 MeV) than higher energies (18 and 22 MeV). For 6, 9, 12, and 15 MeV, 89% of compared points were within 2% or 2 mm. For 18- and 22-MeV electron energies, 75% and 67%, respectively, were within 2% or 2 mm. These results are consistent with the recommendations of AAPM Task Group Report 53.     

Fasciolopslasis--a re-emerging infection in Azamgarh (Uttar Pradesh)

Fasciolopsiasis is endemic in the far east. In India, there have been a few reports of the infection, prior to the 1990's. We report two cases from Azamgarh district of Uttar Pradesh. Both the cases were from nearby villages where water chestnuts are cultivated. These may be a source of infection. Pigs are commonly observed in these areas and and may be the source of ova. The only missing link is the finding of infected snails. Presence of at least three cases (one reported earlier) in the area indicates the potential for the infection to re-emerge. Further epidemiological studies are needed to analyse the various ecological factors of transmission. Fasciolopsiasis is endemic in China, Taiwan, Vietnam and Thailand. In India, (Fascilopsis buski) infections in man have been reported earlier from Assam, Maharashtra, Tamil Nadu and parts of Uttar Pradesh. However, to the best of our knowledge, no such reports have been made since 1990's. We herewith report two recent cases from district Azamgarh, Uttar Pradesh (U.P.), India. Factors, such as cultivation of water chestnuts, presence of snails as intermediate hosts and pigs as definitive host in this geographical area seem to be suggestive of an endemic focus and thus needs further epidemiological survey for preventive and control measures, at the earliest.     

Regulation of the stability of human β interferon mRNA in poly(I)·poly(C)-induced diploid fibroblasts: Anchorage independence of the shutoff mechanism

Exposure of diploid human fibroblast (FS-4) monolayer cultures to poly(I)·poly(C) leads to production of β interferons within the first hour, the rate of production peaks approximately 3 hr after induction and is rapidly shut off by 6–8 hr. The rapid shutoff of interferon production is blocked if the induction is carried out in the presence of 5,6-dichloro-1-β-d-ribofuranosylbenzimidazole (DRB, 40 μM). The rapid and selective inactivation of interferon mRNA that occurs during the shutoff phase in monolayer cultures is anchorage independent and can be preserved in short-term (3–4 hr) suspension cultures prepared from cell monolayers in the shutoff phase. Such inactivation of interferon mRNA is not observed in DRB-containing suspension cultures derived from induced, DRB-treated cell monolayers. Washing of detached, shutoff phase FS-4 cells with buffers lacking Ca²⁺ blocks interferon mRNA inactivation while washing these cells with buffers containing 1 mM Ca²⁺ preserves the shutoff mechanism. Optimal interferon mRNA turn-over requires both active cellular RNA and protein synthesis and incubation at 37°. These data suggest that the selective inactivation of human fibroblast interferon mRNA during the shutoff phase is an active cellular function which does not require the attachment of cells to a solid substrate.