Bone marrow depressant and leukemogenic actions of benzene

Chronic benzene toxicity is expressed as bone marrow depression resulting in leucopenia, anemia or thrombocytopenia. With continued exposure the disease progresses to pancytopenia resulting from a bone marrow aplasia. In recent years evidence has accumulated implicating benzene in the etiology of leukemias in workers in industries where benzene was heavily used. It has been suggested that leukemia is as frequent a cause of death from chronic benzene exposure as is aplastic anemia. This review explores some current ideas on the mechanisms by which benzene may produce these diseases and emphasizes recent work suggesting that the causative agent is a metabolite of benzene.     

Conversion of polycythemia vera to refractory anemia with hyperplastic bone marrow.

Clinical and morphologic findings in the conversion of treated polycythemia vera to pancytopenia with hyperplastic bone marrow (refractory anemia or pancytopenia with hyperplastic bone marrow) are described in light of our own observation. The nomenclature associated with this condition (pancytopenia, chronic erythroleukemia, preleukemia) is not uniform, whereas the morphologic findings are virtually identical. Some patients subsequently develop acute leukemia. The prognosis in cases of refractory anemia with hyperplastic bone marrow following polycythemia vera is, independent of the subsequent acute leukemia, invariably terminal.     

Acquired amegakaryocytic thrombocytopenia purpura in a Rhesus macaque (Macaca mulatta)

A 10-y-old multiparous rhesus macaque presented for an annual routine physical examination. Clinically, the animal had pale mucous membranes, petechial and ecchymotic hemorrhages in multiple sites, and a laceration at the tail base. Severe pancytopenia was noted on hematologic evaluation. The monkey was seronegative for SIV, simian T-lymphotropic virus, simian retrovirus type D, and Macacine herpesvirus 1. Bone marrow evaluation revealed a paucity of megakaryocytic precursors in a hypercellular marrow with marked erythroid hyperplasia. In light of these findings, the diagnosis was acquired amegakaryocytic thrombocytopenia purpura. Due to the poor prognosis of the syndrome and clinical deterioration of the monkey, euthanasia was elected. A definitive cause of the thrombocytopenia was not identified; however, the syndrome may have developed secondary to a recent spontaneous abortion. To our knowledge, this case represents the first reported observation of acquired amegakaryocytic thrombocytopenia purpura in a rhesus monkey.     

Bone Marrow Hypoplasiaresponsive to Testosterone Therapyin a Patient with Panhypopituitarism:Need for Adherence to Androgen Replacement

ObjectiveTo describe the case of a young Saudi male patient with long-term panhypopituitarism and pancytopenia attributable to poor adherence to androgen replacement therapy, which resolved after institution of testosterone treatment and recurred after another interval of poor adherence to recommended therapy.MethodsWe present the clinical and laboratory data before and after treatment with testosterone. In addition, the corresponding histologic changes in the bone marrow are illustrated.ResultsAfter resection of a hypothalamic glioma, panhypopituitarism developed in a 14-year-old Saudi boy. At age 22 years, he had shunt-related meningitis. He was then noted to have pancytopenia, with a platelet count of 54 × 10³/μL, a hemoglobin concentration of 6.9 g/dL, and a leukocyte count of 2.7 × 10³/μL. After treatment of sepsis, the pancytopenia persisted. No underlying cause was detected. Bone marrow biopsy showed a hypocellular marrow with dysplastic megakaryocytes. The patient’s family indicated that he had not been taking his testosterone therapy. Testosterone decanoate (250 mg) was administered intramuscularly daily for 3 days. His platelet count increased to 74 × 10³/μL. Maintenance therapy with testosterone once weekly for 3 weeks and then once every 3 weeks resulted in improved hematologic findings. Repeated bone marrow biopsy after 6 weeks showed normocellular marrow, with disappearance of the megakaryocytic dysplasia. The patient again discontinued his testosterone treatment, and the hematologic abnormalities recurred but were again corrected after supervised testosterone therapy.ConclusionThis case emphasizes the importance of androgen replacement therapy in patients with hypopituitarism, not only for sexual potency, bone strength, and quality of life but also for normal bone marrow function. (Endocr Pract. 2008;14:229-232)     

Clonazepam and dopamine-related stereotyped behavior

The effect of clonazepam on behavioral stereotypy induced by a number of dopaminergic agonists was investigated. Clonazepam inhibited levodopa- and amphetamine-induced behavior in guinea pigs but did not alter lergotrile- or apomorphine-induced stereotypy. The results suggest that clonazepam influences the central dopaminergic system through a direct effect of dopaminergic presynaptic mechanisms.     

Clonazepam and diltiazem both inhibit sodium-calcium exchange of mitochondria, but only diltiazem inhibits the slow action potentials of cardiac muscles

Clonazepam, up to concentrations of 5 x 10(-5) M produced only 15% inhibition of contraction without effecting isoproterenol-induced slow action potentials (APs) of guinea pig papillary muscles. On the other hand, 10(-6) M diltiazem completely inhibited both slow APs and contractions. Both clonazepam and diltiazem inhibited Na+-induced Ca2+ release from isolated mitochondria. The half-maximum effect of clonazepam and diltiazem occurred at 7 and 8 x 10(-6) M respectively. The results suggest that clonazepam more specifically inhibits the Na+-induced Ca2+ release process of mitochondria.     

Bone marrow hypoplasia associated with estrus in ferrets

Bone marrow hypoplasia was characterized in a group of female ferrets during prolonged estrus. All ferrets exhibited hematological changes characteristic of various degrees of bone marrow hypoplasia. Hematological findings included initial thrombocytosis and leukocytosis followed by thrombocytopenia, leukopenia and anemia. Platelet counts below 50,000/microliters were observed in 55% of the ferrets. Hemorrhagic anemia due to thrombocytopenia was the most common cause of death and the mortality rate was 40%. Histopathological findings included bone marrow hypoplasia affecting all cell lines and decreased splenic extramedullary hematopoiesis.     

Type I interferon signaling and B cells maintain hemopoiesis during Pneumocystis infection of the lung

Loss of CD4 T cells is the hallmark of HIV infection. However, type I IFN-producing plasmacytoid dendritic cells may also be lost. This results in susceptibility to an opportunistic infection such as Pneumocystis pneumonia. In addition, regenerative bone marrow failure resulting in pancytopenia is another common problem in advanced stage AIDS. This may be linked to both the failing immune system and recurrent opportunistic infections. We generated lymphocyte-deficient type I IFN receptor-deficient mice (IFrag-/-) to study the effects on Pneumocystis infection of the lung. When IFrag-/- animals were infected with Pneumocystis they died between days 16 and 21 postinfection with minimal pneumonia but severe anemia due to complete bone marrow failure. This included the loss of uncommitted hemopoietic precursor cells. Bone marrow failure was prevented by the reconstitution of IFrag-/- mice with wild-type lymphocytes, especially B cells. T and B cells lacking type I IFN receptor signaling could only partially prevent bone marrow failure in response to Pneumocystis infection. However, the presence of T and B cells lacking type I IFN signaling resulted in compensatory extramedullary hemopoiesis in the liver and spleen. Lymphocyte support of the regenerative capacity of the bone marrow was provided by both type I IFN-dependent and -independent mechanisms that acted synergistically. Our findings point to the requirement of both type I IFNs and lymphocytes in the regenerative capabilities of the hemopoietic system under the pressure of Pneumocystis infection, but not during steady-state hemopoiesis. This may have implications in the management of pancytopenia in AIDS.     

Aging: Effect on neuronal and non-neuronal benzodiazepine binding sites

The frontal cortex, hippocampus, and cerebellum of the Fischer 344 rat were examined for an age-dependent change in neuronal and non-neuronal binding. Clonazepam and Ro5-6669 displaceable [3H]diazepam binding were used as indicators of [3H]diazepam binding on neuronal and non-neuronal membranes, respectively. In both the frontal cortex and the hippocampus, clonazepam displaceable [3H]diazepam binding in the senescent rat was significantly less than the young and mature rat. In the frontal cortex, Ro5-6669 did not significantly displace [3H]diazepam binding in any age group. The Ro5-6669 displaceable [3H]diazepam binding in the hippocampus was not altered with age. In the cerebellum clonazepam and Ro5-6669 displaceable binding in the old rat was significantly less and more, respectively, compared to the young rat.     

Influence of clonazepam on cortical epileptogenic foci in the rat

The antiepileptic action of clonazepam was studied on epileptogenic foci induced by penicillin in sensorimotor cortex in acute experiments in rats. Clonazepam (1 mg/kg intraperitoneally) only moderately decreased the frequency of interictal discharges of single cortical focus and delayed the propagation of discharges into the ipsilateral occipital region. On the contrary, clonazepam failed to influence the callosal projection of interictal discharges in single unilateral as well as in two symmetrical foci. Spontaneous transition of interictal discharges into ictal phases regularly seen when two symmetrical foci were formed was only delayed but not blocked by clonazepam. It may be concluded that clonazepam exhibits only a weak anticonvulsant action against cortical foci and against secondary generalization of epileptic activity.     

A Study of Cytological Changes in the Bone Marrow of Patients with Severe Fever with Thrombocytopenia Syndrome

Background

Peripheral blood leucopenia and thrombocytopenia are the main manifestations in severe fever with thrombocytopenia syndrome (SFTS) patients. However, the underlying causes are poorly understood. Therefore, we aimed to investigate cytology of bone marrow samples collected from SFTS patients.

Methods

10 SFTS patients were identified by typical clinical manifestations, detection of peripheral blood leucopenia and thrombocytopenia, and nucleic acid-based detection of the newly identified bunyavirus. SFTS patients, along with 10 participants with acute aplastic anemia and 10 healthy volunteers were enrolled in this study after written informed consent to undergo bone marrow cytological examination.

Results

We observed similar bone marrow properties in SFTS patients and healthy volunteers, significantly different from the characteristics observed in acute aplastic anemia patients.

Conclusion

Similarities between bone marrow samples collected from SFTS patients and healthy volunteers suggest that peripheral blood leucopenia and thrombocytopenia do not result from bone marrow cell plasticity.     

Autoradiographic Localization of Benzodiazepine Receptor Binding in Dissociated Cultures of Fetal Mouse Cerebral Cortex

Autoradiography utilizing photoaffinity labelling with [3H]flunitrazepam was used in living cultures of fetal mouse cerebral cortex in situ to localize benzodiazepine receptor binding sites. There was a predominant localization of silver grains over neurons; however, substantial labelling also occurred over nonneuronal background cells. Clonazepam (0.1 microM) and Ro 5-4864 (0.1 microM) displaced substantial numbers of silver grains over neurons and background cells, respectively. In addition, clonazepam displaced 58-68% of specific grains over background cells and Ro 5-4864 displaced 30% of grains over neurons, suggesting that multiple cell types in the CNS may participate in the neuropharmacologic actions of the benzodiazepines.     

脐带间充质干细胞与再生障碍性贫血

再生障碍性贫血(aplastic anemia,AA)是由于物理、化学、生物或不明因素作用使骨髓造血干细胞和骨髓微环境严重受损,造成骨髓造血功能降低或衰竭,以全血细胞减少为主要表现的一组综合征。间充质干细胞(MSC)是属于中胚层的一类多能干细胞,主要存在于结缔组织和器官间质中。不仅具有多向分化潜能,还有多种免疫调节作用。许多研究表明MSCs抑制同种异体效应T淋巴细胞增殖,还能下调T淋巴细胞表面的活化分子CD25、CD38、CD69的表达。MSCs对DCs的分化、成熟和活化具有抑制作用,改变DCs的细胞因子分泌,使成熟的DCl分泌TNF-a减少,DC2分泌IL-10增加,从而抑制T淋巴细胞增殖。MSCs能够抑制IL-2和IL-15介导的NK细胞增殖,使IL-2刺激NK细胞分泌的IFN-y减少。通过这些机制来干预再生障碍性贫血,同时研究发现MSCs免疫原性较低。尤其脐带MSC,因为其独特优势,目前已经成为干细胞干预治疗AA的研究热点。     

Quantitative determination of clonazepam in plasma by gas chromatography-negative ion chemical ionization mass spectrometry

A gas chromatographic-negative ion chemical ionization mass spectrometric (GC-NCI-MS) method for the quantitative analysis of clonazepam in human plasma is described. Clonazepam (M_r = 315) was derivatized by N,O-bis-(trimethylsilyl)trifluoroacetamide with 1% trimethylchlorosilane. A pre-conditioning procedure involving injection of a silyl-8 and ethyl acetate extraction solution from plasma reduces the interaction between clonazepam-TMS and the analytical system. The routine limit of quantification was set to be 0.25 ng/ml with an injection volume of 2 μl and a sample volume of 1 ml. The signal-to-noise ratio was greater than five. The detection limit for clonazepam can reach 0.1 ng/ml. The isotope clonazepam-d₅ was used as the internal standard.     

Clonazepam use in pregnancy and the risk of malformations

BACKGROUND: Clonazepam (Klonopin) is a benzodiazepine that has been used widely to treat seizures and conditions such as panic attacks and anxiety disorder. However, the current findings about its use in pregnancy are derived from limited studies of small sample size. Because it is commonly prescribed during pregnancy, more information about its safety is needed. METHODS: The medical records of 28,565 infants were surveyed as part of a hospital-based malformation surveillance program to identify those who had been exposed prenatally to an anticonvulsant, including clonazepam. RESULTS: During a 32-month period, 166 anticonvulsant-exposed infants were identified; 52 had been exposed to clonazepam, 43 as monotherapy. A total of 33 (76.7%) of the monotherapy infants were exposed during the first trimester. One (3.0%) infant had dysmorphic features, growth retardation, and a heart malformation (tetralogy of Fallot). CONCLUSIONS: This study did not observe an increase in major malformations in births exposed to clonazepam monotherapy. However, this study is not large enough to have adequate power to determine whether or not the rate of major malformations is increased in clonazepam-exposed pregnancies. No increase has been identified in three other case series. Although the number of patients in this series was larger than previous reports, continued monitoring of pregnancies is needed to determine whether or not clonazepam is teratogenic.     

Chronological observations on hemato-pathological changes in chicks inoculated with chicken anemia agent

Chicks were inoculated with the Gifu-1 strain of the chicken anemia agent (CAA) on the day of hatching. They manifested distinct anemia accompanied with pancytopenia 8--20 days after inoculation. Discoloration of the bone marrow and atrophy of the thymus began to be seen 6 days after inoculation. Histologically, hematopoietic cells began to decrease and large blastic cells to appear in the bone marrow 4--6 days after inoculation. Hypoplasia and subsequently aplasia occurred to all over the bone marrow 8 days after inoculation. In the bone marrow erythrocytopoiesis was noticed first 16--18 days after inoculation, granulocytopoiesis later, and transient hyperplasia finally. At last, the bone marrow returned to a normal condition 32 days after inoculation or later. In the thymus the depletion of cortical lymphocytes became distinct 4--6 days after inoculation, and lobular atrophy 8 days after inoculation or later. The depletion of lymphocytes in the other lymphatic tissues and hemorrhage in the lamina propria of the proventriculus were observed only in the anemic phase. The results mentioned above indicated that the anemia induced by CAA was caused by the disorder of hematopoietic cell formation in the bone marrow. It was also noteworthy that cortical lymphocytes in the thymus began to decrease remarkably soon after inoculation.     

Effects of clonazepam on picrotoxin-induced convulsions.

The convulsant effects of four doses of picrotoxin (PX)-2, 3, 4, and 6 mg/kg s.c.-were evaluated in the first part of the study. The 4-mg/kg dose, which elicited minimal seizures in all animals, generalized tonic-clonic (major) seizures in 75% of rats and fatal outcome in 69% of rats, was chosen for the second part, i.e. for testing the anticonvulsant action of clonazepam (Rivotril Roche, 0.1 or 1 mg/kg i.p.). Clonazepam exhibited a dose-dependent action against PX-induced seizures, being more efficient against major than against minimal seizures.     

Apoptotic index by Annexin V flow cytometry: adjunct to morphologic and cytogenetic diagnosis of myelodysplastic syndromes

The myelodysplastic syndromes (MDS) are clonal hematologic malignancies characterized by pancytopenia, dysplastic hematopoiesis, and a propensity to leukemic transformation. Increased apoptosis has been noted in MDS as a possible explanation for ineffective hematopoiesis, with lower levels in progression to and in de novo acute leukemia. Apoptosis can be measured by binding of Annexin V to exposed membrane phosphatidylserine. We postulated that the apoptotic index would aid in the differential diagnosis of MDS versus other hematopoietic diseases. We examined 33 bone marrow aspirates suspected of hematopoietic malignancy for apoptotic index by Annexin V analysis using a Becton Dickinson FACStar+ flow cytometer. The apoptotic index was expressed as the percentage of Annexin V-positive cells divided by total mononuclear cells in the gate. By standard morphologic analysis, 16 cases were diagnosed as MDS (9 refractory anemia [RA], 2 refractory anemia with ringed sideroblasts [RARS], 1 refractory anemia with excess of blasts [RAEB], 3 chronic myelomonocytic leukemia [CMML], and 1 unclassified), 11 as acute leukemia (AL), 6 as myeloproliferative disorders (MPD). Eight cases (uninvolved marrow of five patients with lymphoproliferative disorders [LPD], one patient with multiple myeloma, and two patients with anemia of chronic disease) served as nonneoplastic controls. A higher degree of apoptosis was observed in MDS (mean = 44.7%; range = 29.5--60%) compared with MPD (mean = 8.2%; range = 2.3--15.4%), AL (mean = 16.1%; range = 5.1--29.4%), and control marrow samples (mean = 11.6%; range = 1.5--21%). Additionally, the apoptotic index was significantly higher in MDS compared with MPD (P < 0.0001). In conclusion, a high apoptotic index occurs in MDS, supporting previous reports and suggesting that Annexin V analysis can be used as an adjunct in the diagnosis of MDS versus MPD. This would be particularly useful for the often-difficult distinction between early MDS and early MPD cases with equivocal morphology.     

Peripheral Blood and Bone Marrow Abnormalities in the Acquired Immunodeficiency Syndrome

In reviewing the peripheral hematologic manifestations, bone marrow changes and clinical course in 41 consecutive patients with acquired immunodeficiency syndrome (AIDS), frequent findings included anemia (95%), leukopenia (76%), bone marrow hypercellularity (73%) and pancytopenia (41%). These hematologic abnormalities were not clearly associated with specific clinical manifestations of AIDS, but support the conclusion that the hematopoietic system is a target organ in AIDS. The mechanisms of these abnormalities still need to be evaluated. Clinicians should be aware of these commonly encountered changes.     

Clinical aspects of cytomegalovirus infection after allogenic bone marrow grafts

CMV infection is one of the major infection after bone marrow transplantation. CMV viremia was systematically studied in 66 patients with aplastic anemia or leukemia undergoing BMT. 57% patients had CMV viremia with a frequency peak between 7 and 9 weeks after transplant. Clinical symptoms found during viremia were pancytopenia, fever, cytolytic hepatitis. Interstitial pneumonitis was found only in 4 cases. In 3 cases, viremia was not associated with clinical symptoms. Survival was identical to the group of patients without viremia. Viremia was positively associated with the presence of high anti-CMV antibody titer in donor or recipient before transplant, or to a lymphocyte proliferative response against CMV antigens in donor or recipient before BMT. Granulocyte transfusions increased the frequency of CMV viremia. CMV infection was significantly associated with acute and chronic graft versus host disease. The relation showed between these parameters and viremia provides a basis for an accurate diagnosis of CMV infection and a better background for the study of prophylactic or curative treatment of CMV infection.