[Safety and survival analysis of haplo-identical hematopoietic stem cell transplantation in patients with severe aplastic anemia who had previous failure to antithymoglobulin treatment]

Objective: To investigate the safety and efficacy of haplo-identical hematopoietic stem cell transplantation (haplo-HSCT) conditioning with the same dosage form of antithymoglobulin (ATG) in patients with severe aplastic anemia (SAA) failure to ATG. Methods: This was a retrospective cohort study. A total of 65 patients with SAA who failed ATG treatment and received haplo-HSCT conditioning with the same dosage of ATG at the Institute of Hematology, Peking University People's Hospital between July 2008 and October 2020 were included as the ATG treatment failure group. An additional 65 SAA patients who applied ATG for the first time during haplo-HSCT were randomly selected by stratified sampling as the first-line haplo-HSCT group. Baseline clinical data and follow-up data of the two groups were collected. Conditioning-related toxicity within 10 days after ATG application and long-term prognosis were analyzed. The Kaplan-Meier was used to calculate the overall survival rate, and the Log-rank test was applied to compare the rates of the two groups. Results: In the ATG treatment failure group, there were 36 males and 29 females, and the age at the time of transplantation [M (Q1, Q3)] was 16 (8, 25) years. In the first-line haplo-HSCT group, there were 35 males and 30 females, with a median age of 17 (7, 26) years. Within 10 days of ATG application, the incidence of noninfectious fever, noninfectious diarrhea, and liver injury in the ATG treatment failure group was 78% (51 cases), 45% (29 cases), and 28% (18 cases), respectively, and in the first-line haplo-HSCT group was 74% (48 cases), 54% (35 cases), and 25% (16 cases), respectively; the difference between the two groups was not statistically significant for any of these three parameters (all P>0.05). For graft-versus-host disease (GVHD), there was no significant difference between the ATG treatment failure group and the first-line haplo-HSCT group in the development of 100 day Ⅱ to Ⅳ acute GVHD (29.51%±0.35% vs. 25.42%±0.33%), Ⅲ to Ⅳ acute GVHD (6.56%±0.10% vs. 6.78%±0.11%), and 3-year chronic GVHD (26.73%±0.36% vs. 21.15%±0.30%) (all P>0.05). Three-year overall survival (79.6%±5.1% vs. 84.6%±4.5%) and 3-year failure-free survival (79.6%±5.1% vs. 81.5%±4.8%) were also comparable between these two groups (both P>0.05). Conclusions: Compared with no exposure to ATG before HSCT, similar early adverse effects and comparable survival outcomes were achieved in patients with SAA who failed previous ATG treatment and received haplo-HSCT conditioning with the same dosage form of ATG. This might indicate that previous failure of ATG treatment does not significantly impact the efficacy and safety of salvaging haplo-HSCT in patients with SAA.

[Scanning electron microscopic observation of the external morphology of Dermatophagoides farinae at different developmental stages]

OBJECTIVE

To investigate the morphological characteristics of Dermatophagoides farinae at different developmental stages.

METHODS

The cultured D. farinae was isolated, and the external morphological features of mites at various developmental stages were observed using scanning electron microscopy (SEM), including egg, larva, nymph and adult stages.

RESULTS

The D. farinae egg appeared a long oval shape, and the larval mites had three pairs of legs. The nymph had four pairs of legs and underdeveloped genital pores containing genital setae and anal setae, and adult mites appeared long and oval in shape, with decorative patterns on epidermis, and had four pairs of legs. In male adult mites, remarkable thickening of the leg I and thicker and longer leg III than the leg IV were seen, and ventral genital regions were found between the basal segments of legs III and IV; the anus was surrounded by a circular peri-anal ring, with a pair of anal suckers and anal setae within the ring. In the female adult mites, slender legs III and IV with an equal length were seen, and a "λ-shape" genital hole was observed on the ventral surface, with a crescent-like genital plate in the anterior part, and the anus appeared a longitudinal slit.

CONCLUSIONS

An SEM observation of the external morphology of D. farinae provides understandings of the morphological characteristics of D. farinae, which is of great significance for the classification and identification.

[Outcomes of alternative donor allogeneic hematopoietic stem cell transplantation for Fanconi anemia: a five cases report]

Five patients with Fanconi anemia who received hematopoietic cell transplantation were retrospectively analyzed. The conditioning regimens included fludarabine, cyclophosphamide and anti-thymocyte globulin. Two patients received both bone marrow and peripheral blood stem cells as the source of stem cell grafts from haploidentical matched related donors, while the others received peripheral blood stem cells from unrelated donors. All patients tolerated well and reached hematopoietic reconstitution. One patient died of intracranial infection. During follow-up, 4 patients survived independent of transfusion with full donor chimerism.

[Clinical value of PCR for viral detection of bronchoalveolar lavage fluid in the diagnosis and treatment of pneumonia after allogeneic hematopoietic stem cell transplantation]

Objective: To analyze the clinical value of real-time PCR for virus detection in the diagnosis and treatment of patients after allo-HSCT who had no infection evidence of pneumonia using routine pathogen detection panel. Methods: The clinical data of 71 episodes with acute lung injury from May 2015 to March 2017 after allo-HSCT in hematology department of Peking University People's Hospital (PKUPH) were retrospectively analyzed. PCR for virus detection and other routine pathogen detection tests were performed on bronchoalveolar lavage fluid (BALF) samples. Results: Among 71 episodes with acute lung injury, a total of 15 patients were diagnosed as lower respiratory tract disease merely associated with virus (detection rate of 21.13%) , 19 episodes were absent of lower respiratory tract infection. The median time from allo-HSCT to the occurrence of lung injury were 176 (49-1 376) d and 196 (57-457) d respectively (z=-0.191, P=0.864) . There were no statistical differences for baseline characteristics and clinical features between two groups. The 100-day attributable mortalities were 13.3% (2/15) and 26.3% (5/19) (χ(2)=0.864, P=0.426) . Patients with low-dose steroids treatment had favorable outcome than those with high-dose steroids treatment (the dose of methylprednisolone ≥250 mg/d as standard) [4.2% (1/24) vs 60.0% (6/10) ]. In patients with detectable virus in BALF, 2 patients died with early high-dose steroids treatment, while 11 patients survived with no steroids treatment or late application. Conclusions: Virus infection should be considered in post-HSCT pneumonia patient with negative result using routine pathogen detection panel. Expanding virus detection panel by PCR in BALF could increase diagnostic precision and might be instructive to treatment.

[Analysis of risk factors related to the prognosis in patients with late-onset severe pneumonia after allogeneic hematopoietic stem cell transplantation]

Objective: To investigate the prognostic factors of late-onset severe pneumonia (LOSP) in patients who underwent allogeneic hematopoietic stem cell transplantation (allo-HSCT). Methods: From January 2009 to December 2015, 68 patients with LOSP after allo-HSCT at Peking University Institute of Hematology were enrolled. In this retrospective study, univariate and multivariate analysis were used to evaluate the prognostic factors for LOSP after allo-HSCT. Results: The median time from allo-HSCT to the development of LOSP was 213 (90-2 330) days. The overall survival rate was 42.6% (29/68). The median survival time from LOSP to death was 21 days. Early mortality was defined as death within 21 days after LOSP, as late death more than or equal to 21 days. The median oxygenation index was 199.15 (92.21-290.48) mmHg. LOSPs in thirty-two patients (36.8%) were caused by virus, bacteria, fungi or mixed pathogens. The median C-reactive protein (CRP) was 75.65 (0.94-451.00) mg/L. The median procalcitonin (PCT) was 0.66 (0.00-249.00) μg/L. The higher PCT value indicated an early higher mortality rate by the ROC curve (PCT: cut-off ≥0.94 μg/L). Furthermore, multivariate analysis suggested that PCT more than or equal to 0.94 μg/L was a risk factor for early death of LOSP (OR=5.77, 95%CI 1.66-20.11, P=0.006). LOSP occurred later or equal to 213 days after allo-HSCT was also a risk factor of early death in LOSP (OR=4.74, 95%CI 1.33-16.89, P=0.017). No previous history of chronic graft versus host disease (GVHD) (OR=4.50, 95%CI 1.58-12.83, P=0.005) and LOSP later or equal to 213 days (OR=4.40, 95%CI 1.61-11.99, P=0.004) were the risk factors of late death in LOSP. Conclusions: PCT more than or equal to 0.94 μg/L and LOSP later or equal to 213 days are the risk factors of early death in LOSP. No previous chronic GVHD and LOSP later or equal to 213 days are the risk factors of late death in LOSP.

A NOTE ON THE FILTRATION OF THE VIRUS OF HERPETIC ENCEPHALITIS AND OF VACCINIA

The virus of herpetic encephalitis and the virus of vaccinia can be demonstrated in the filtrate, if a broth emulsion of fresh tissue containing the virus, is passed through a Berkefeld V filter.

STUDIES IN ULTRAFILTRATION

We are submitting this series of experiments as observed facts, realizing that there are so many uncertainties in this form of indirect observation that great caution must be exercised in drawing conclusions of any kind. The most serious of the possible errors involved is that the active substances which we have studied, the enzyme—the bacteriophage—and the several varieties of virus, may not be free in our suspensions, but are adsorbed to larger particles. The peculiar difficulties encountered in filtering herpes virus particularly suggest a source of error of this kind, and if we are right in assuming the intracellular position of this virus in the nervous tissue, it is more than likely that most of the virus obtained in suspension may be closely associated with protein particles derived from the cells. Keeping all this in mind, we may, nevertheless, derive a certain amount of information from our experiments as follows: 1. The order of magnitudes of the pure proteins with which we have worked,—namely, crystallized egg albumen, crystallized serum albumen and purified casein,—follows the order of molecular weights of these substances as determined by Cohn. As far as casein is concerned, the size indicated by filtration in comparison with collargol is far greater than it should be by calculations which take a molecular weight of 192,000 as the point of departure. While one cannot be sure of the reason for this, there are many possible explanations such as considerable swelling of the casein partides, aggregation of molecules and the fact that casein is not at its isoelectric point under the conditions of filtration and surely present as a salt. 2. Trypsin, even in the certainly very impure condition in which we employed it, is but very slightly larger than serum albumen and distinctly smaller than casein. In its pure form it may well be much smaller even than our filtrations indicate, but certainly not larger. This relatively small size of trypsin may have considerable bearing upon the question of whether or not the lytic agents spoken of as "bacteriophage" are substances of the nature of enzymes, or whether they are more comparable to the filtrable virus, as supposed by d'Hérelle. 3. Herpes virus, the Rous chicken sarcoma and a staphylococcus bacteriophage were all subjected to filtration at pH 7.2 and at hydrogen ion concentrations higher than 8, which is given by Olitsky and Boëz as the isoelectric point of foot-and-mouth disease, but failed to pass membranes which, at the same pressures, were permeable for casein and collargol. The bacteriophage and the Rous sarcoma with considerable regularity passed through membranes which held back colloidal arsenic trisulfide. We have cited only a few of the experiments which were actually done, every one of the tests tabulated being merely representative of a number of others that were omitted for economy of space. The herpes virus we have had greater difficulty in filtering. We cite one experiment with a 2 per cent acetic-collodion membrane and another with a 1.5 per cent membrane through which the herpes virus passed, the membrane being so controlled that gross leakage could be excluded. We believe that the difficulty here is very largely due to the fact that in preparing the herpes virus for filtration it cannot be separated from considerable amounts of brain material, from which, perhaps, it is not easily dissociated. This would be natural if the herpes virus were intracellularly located, as we believe it to be. This experiment and similar ones, however, incline us to believe that the herpes virus is not far different from the Rous sarcoma virus and the bacteriophage, as far as filtration through membranes is concerned. It certainly is not smaller than either of these substances and probably, as we judge from a few experiments carried out at higher pressures, is not much larger. It may be assumed, therefore, that in the form in which we were able to procure the bacteriophage and the two varieties of virus investigated by us, they were of a magnitude larger than casein and collargol and smaller than colloidal arsenic. The weak point in drawing our conclusions is the fact that we were not in a position to measure for ourselves with any accuracy the actual sizes of collargol and arsenic trisulfide particles. Accepting the general views of Bechhold and others, however, our experiments would define the sizes of the separticular substances as larger than 20 mµ and probably smaller than 100 mµ. The order of magnitudes of the substances measured by us would then be as follows: Crystallized egg albumen Crystallized serum albumen Trypsin Collargol Casein Bacteriophage, Rous sarcoma virus, herpes virus Arsenic trisulfide Our experiments show little agreement with the work of Levaditi and Nicolau and of Levaditi, Nicolau and Galloway. In their recent filtration tests of foot-and-mouth disease this virus is reported by them as passing through membranes that held back trypsin, indicating a size much smaller than any of the viruses measured by us. Our results, on the other hand, are in actual measurements comparable to those of Olitsky and Boëz, not only in the fact that the viruses with which we worked correspond approximately to the size determined by them for foot-and-mouth disease, but that the percentage of collodion in membranes permeable for virus and impermeable for colloidal arsenic corresponds almost exactly to our own. This gives us confidence that the technique developed may be more easily standardized than we at first believed and that the method of ultrafiltration, owing to the great ease with which membranes of relatively standard size may be made, may have valuable applications in the investigation of bacteriological and immunological problems.

IMMUNOLOGICAL STUDIES WITH HERPES VIRUS WITH A CONSIDERATION OF THE HERPES-ENCEPHALITIS PROBLEM

In the preceding experiments observations have been reported upon the nature of herpes virus which confirm the suspicion that the virus is intracellularly located in the infected nervous system. In regard to the immunological conditions existing in this disease, our experiments have reaffirmed that herpes virus can be neutralized with the serum of actively immunized animals and have offered an explanation for the irregularity of the results of others, as well as our own. It has been found that brain extracts possess some virus-neutralizing power, but considerably less than the serum of the corresponding animals. Attempts at passive immunization with neutralizing serum were uniformly negative, even when the serum was introduced into the cisterna magna 12 to 24 hours before infection with the virus. It has been shown that active immunity can be attained only when some degree of reaction to the living virus has occurred. Rabbits which survived neutralized serum-virus mixtures did not acquire immunity nor did those treated with virus phenolized to the extent of actual destruction. This point suggests a reinvestigation of the Semple method of rabies immunization. In so far as our studies touched upon the herpes-encephalitis problem we have uniformly failed in attempts to transfer herpes virus directly from man to rabbits. These results are in contradiction to those of most of the earlier workers, but in keeping with the recent reports of Flexner and Amoss. Attempts to overcome the difficulty of transfer by the recently published technique of Perdrau were unsuccessful. Furthermore, animals repeatedly treated with human encephalitis material, either fresh or glycerolated, as practised in the Perdrau method, failed to acquire the slightest degree of immunity to subsequent herpes inoculation. By the inoculation of very small doses or by infection of partially immunized rabbits, as described above, we have succeeded in modifying the characteristic herpetic syndrome in rabbits in a manner which simulates many of the clinical features of human encephalitis. Our own experience forces the conclusion that no valid proof exists upon which can be based an assertion concerning the identity of the virus of herpes with that of encephalitis lethargica. Either the two viruses are entirely unrelated, or else prolonged sojourn in the central nervous system of man attenuates the virus for rabbits to an extent analogous to that in which rabies virus is attenuated for man by passage through rabbits. The isolated successes of Levaditi and of Doerr and their assistants might thus be regarded as fortunate exceptions in which material incompletely attenuated had been at their disposal. We suggest this point of view as an alternative working hypothesis largely because the results we are reporting, as well as those of Flexner and Amoss, are in flat contradiction to the reported successes of earlier workers and the more recent experiments of Perdrau. The experiments of the latter, as described, cannot be explained by the occasional existence of spontaneous encephalitis in his rabbits, nor by the assumption that a herpes virus fortuitously coexisted with that of lethargic encephalitis in his material, inasmuch as this material alone at first injection or in the unglycerolated state failed to infect. It is also possible to conceive that human beings may, by repeated skin infections, attain a not inconsiderable partial immunity to herpes virus, which would explain the nature of the clinical course (as in our partial immunity rabbits) as well as the innocuousness of direct injections of herpetic virus into man, as reported by Bastai and Busacca, and the finding of herpes virus in human beings not suffering from lethargic encephalitis. These suggestions are discussed in order to give this important problem the broadest possible consideration. For the time being, however, such reasoning cannot be taken as more than a logical possibility impressed upon us by our partial immunization experiments. All other experimental evidence obtained by direct inoculations with the limited material at our disposal tends to render identity of the two varieties of viruses unlikely.

Experimental Results on the Centipede Game in Normal Form: An Investigation on Learning

We analyze behavior of an experiment on the centipede game played in the reduced normal form. In this game two players decide simultaneously when to split a pie which increases over time. The subjects repeat this game 100 times against randomly chosen opponents. We compare several static models and quantitative learning models, among them a quantal response, model reinforcement models and fictitious play. Furthermore, we structure behavior from period to period according to a simple cognitive process, called learning direction theory. We show that there is a significant difference in behavior from period to period whether a player has decided to split the pie before or after the opponent. Copyright 1998 Academic Press.

CENTRIFUGE EXPERIMENTS WITH THE VIRUS OF VACCINIA

Centrifuge experiments have been carried out with cell-free, active filtrates of vaccinia virus. The experiments have shown that the virus can be concentrated by this method, even in filtrates which have been subjected to prolonged preliminary centrifugation to throw down any inert particles which may have been present in the original filtrate. This fact, together with the knowledge that the virus can be almost completely held back by the Berkefeld N filter, as reported previously (5) indicates that the virus may be of considerable size.