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The toxicity of 17 alpha-cyanomethyl-17 beta-hydroxy-estra-4, 9-dien-3-one (STS 557) was studied by its oral administration of 0.1, 1.0 or 10.0 mg/kg/day to Wistar rats for six months, and of 0.01, 0.1 or 1.0 mg/kg/day to beagle dogs for six months, respectively. Levonorgestrel at a dose of 1.0 mg/kg/day was used as the standard in the dog study. With respect to the progestational activity of the compound the main target organs were the hypophysis, the reproductive organs and the adrenals. Mammary hyperplasia was observed in dogs treated with STS 557 or levonorgestrel at the dose of 1.0 mg/kg/day, but in no case mammary nodules could be detected. At the dose of 1.0 mg/kg/day STS 557 and levonorgestrel were found to increase the plasma insulin response to i.v. glucose in bitches, but neither the mean blood glucose levels nor the glucose utilization were affected. Moreover, during administration of both steroids to dogs temporary changes in serum concentrations of triglycerides and total cholesterol were noted. The results obtained in rats and dogs from functional and morphological investigations did not reveal any toxic side effects of STS 557 on the liver, the kidneys, the bone marrow or on blood coagulation. The effects on the reproductive organs observed following STS 557 especially in dogs are related to both the hormonal effects of the compound and the specific response of the dog to potent progestagens.

The new positive-inotropic and vasodilatating drug Pimobendan (racemate), 4,5-dihydro-6-[2-(4-methoxyphenyl)-1H-benzimidazole-5-yl]-5-methyl-3 (2-H)-pyridazinone, and its enantiomers were investigated with regard to their cardiotoxicity in young adult female Chbb: Beagle dogs. The racemate and the (-)-isomer (eutomer) were intravenously injected once daily for 4 consecutive weeks at doses of 0.25, 0.75 and 2.25 mg/kg, and the (+)-isomer (distomer) at doses of 0.75, 2.25 and 6.75 mg/kg, respectively. Clinical signs, hematological, clinico-chemical, ophthalmologic and electrophysiological parameters were monitored. Plasma concentration-time profiles of the parent compound and the major metabolite UD-CG 212 were established on day 1 and in week 4 using an HPLC assay. Partial areas under the curves from 0.08 h to 1 h (AUC0.08-1 h) as well as the plasma concentration at time point 0.5 h/C0.5 h) were used for statistical calculations. Necropsy and histopathologic examination were performed after completion of the treatment period. Reduction of the blood pressure occurred already at low dosages of the racemate and the eutomer, but only in high dose distomer-treated animals. A tendency to tachycardia developed only in high dose females receiving the racemate. Consequently, with respect to the pharmacological effects and the adverse events, the racemate is equivalent to the eutomer. Plasma concentrations of parent compound and metabolite were dose-linear for racemate, eutomer and distomer within the dose range 0.25-2.25 mg/kg.d at both time points. There were no significant effects of form or repeated administration. A moderate increase of AUC0.08 1 h and C0.5 h could be seen on day 23 for the distomer indicating a stereoselektive metabolism of the latter. Histologic changes of the valvular and parietal endocardium being termed jet lesion were observed after administration of the racemate (> or = 0.75 mg/kg.d) and the eutomer (> or = 0.25 mg/kg.d) at distinctly lower doses than after the distomer (> or = 2.25 mg/kg.d). Furthermore, extent and severity of the morphologic lesions were found to be higher in dogs exposed to the racemate or the eutomer than in those receiving the distomer. The results gave evidence that the so-called cardiotoxicity by Pimobendan in dogs resulted from the exaggerated pharmacodynamic effect but not from the chemical nature of the compound per se. They corroborate also the previously raised assumption that the exaggerated pharmacodynamic activity of cardiotonic compounds in the broadest sense accounts for their morphologic adverse effects in experimental animals.

Although the general liver morphology is similar in all mammals, there are some structural features in apparently healthy laboratory rodents. These peculiarities are known to be influenced by a great variety of endogenous and exogenous factors. Incidence, intensity, development and disappearance of such elements as extramedullary haemopoiesis, polyploidy, intranuclear and intracytoplasmic inclusions depend markedly upon genetics, age, hygienic condition, hormonal regulation and nutrition of the animals. It is concluded from this short review that the term "normal histology" should only be understood as being relative and that it may only be applied to a given, well defined animal population held under well defined conditions.

To investigate the effects of social isolation on host resistance male mice were housed either individually (IH) or in groups of four or five (GH). All animals were infected with MengoM,L virus. Incubation time (INCUB), duration of illness (ILL), death rate (DR), histopathological changes, and serum corticosterone levels (CORT) were recorded. First, the effect of IH starting 4 days prior to infection was studied in 5 different inbred strains. Next, the effect of different IH length was examined, and the role of T-cells was investigated by comparing euthymic (+/+) and athymic (nu/nu) NMRI mice. Finally, the effects of the infection on CORT in IH and GH mice were compared in C57BL/6 mice. The major findings were: 1. IH significantly increased ILL in all but the DBA/2 strain, whereas DR was not affected except in C57BL/6. 2. Longer IH (starting 35 [DBA/2] or 10 [NMRI] days prior to virus inoculation) significantly shortened INCUB and prolonged ILL, but IH starting on the day of virus inoculation [DBA/2] significantly prolonged INCUB and shortened ILL. 3. NMRI nude mice exhibited an unaltered DR accompanied by a tremendously prolonged INCUB. 4. Investigations in C57BL/6 mice revealed a significant rise of CORT after infection. This increase was higher in IH compared to GH mice. It is suggested that IH attenuates T-cell mediated inflammatory processes and/or increases macrophage activation, which in turn results in a prolonged course of the disease.

Out of the group of 2-amino-oxazoles 1 was found to be the most potent antiviral compound. Following p.o. or s.c. administration to rats, the 14C-labeled 1 was quickly and completely absorbed. The TRA was eliminated mainly via the kidneys and the liver with half-lives between 32 and 42 h. The acute pharmacodynamic effects of 1 were decrease of blood pressure, bradycardia, and inhibition of both gastric emptying and acid secretion. On smooth muscles spasmolytic and alpha-anti-adrenergic actions were predominant. After single administration the following MTD's were determined: 30 (mouse), 20 (rat), 10 mg/kg i.v. (pig), and 500 (mouse, rat), greater than 100 mg/kg p.o. (pig), respectively. In a subchronic toxicity study in rats, oral doses of 1 between 15 and 240 mg/kg given daily for 4 weeks were tolerated without any severe alterations related to the drug.

A great number of animal models for disturbances of the haemostasis is known (Dodds 1981; Gites et al 1981). They are found in farm animals, domestic (outpatients) and laboratory animals. As in man, lesions such as haemorrhagic diseases, thrombotic conditions and disseminated intravascular coagulation (DIC) can occur as hereditary or acquired diseases and, from the clinical point of view, as an isolated form or as consequence of other pathological conditions. In this short review, spontaneously occurring lesions are predominantly considered.

Patients treated with prothrombin complex concentrates (PCC) have frequently been found to develop thrombotic events (Kaspar 1975; Cederbaum 1976). Therefore, PCC must be regarded as potentially thrombogenic substances (Elodi 1977). In order to reduce the risk of thromboembolic complications the addition of heparin was recommended (Menache and Roberts 1975).

The contact with or uptake of xenobiotics and/or infectious agents by men and animals may cause alterations of tissues, organs or the whole organism. On the other hand, living material requires a defined content of trace elements. Changes of these often unknown, optimal contents of trace elements are connected with deviations from the normal state.

Summary The effects on peritoneal macrophages of some chemotherapeutic agents administered subcutaneously to conventional male AB/Jena mice were studied. β-[1-ethyl-(-5-bis-(β-chloroethyl)aminobenzimidazolyl-(2)]-DL-alanine (IMET 2925 ), β-[1-phenyl-5-bis-(β-chloroethyl)-amino-benzimidazolyl-(2)]-DL-alanine (IMET 3164), and γ-[1-phenyl-5-bis-(β-chloroethyl)-amino-benzimidazolyl(2)]-butyric acid (IMET 37/70) evoked a pronounced variation of the cell surface consisting in a shortening, coarsening and reduction in number of the microvilli and other projections. Likewise, 1.3-bis(piperidinomethyl)-5-ethyl-5-phenyl-barbituric acid induced a flattening of the surface, but the structures appeared to be increased in number per area. Chlorambucil, 6-mercaptopurine, and 5-fluoro-uracil failed to provoke any obvious change in the threedimensional cell surface structure. These morphological findings are consistent with functional results reported previously.

The effect of intraperitoneally applied 1.3-bis(piperidinomethyl)-5-ethyl-5-phenyl-barbituric acid on immune response in mice has been investigated. A marked depression of antihuman erythrocyte agglut

N-Methyl-N-nitroso-β-d-glucosylamin und 1-N-Methyl-N-nitrosamino-1-desoxy-d-glucit induzierten nach mehrwochiger peroraler Applikation bei konventionellen Wistar-Ratten Vormagen- und Lebertumoren, 1-N-Methyl-N-nitrosamino-1-desoxy-d-glucit auserdem selektiv Larynx-, Pharynx- und Oesophagusgeschwulste. Dagegen waren N-Methyl-N-nitroso-β-d-galactosylamin und 1-N-Methyl-N-nitrosamino-1-desoxy-d-galaktit nicht onkogen.

By means of a new parameter “t” characterizing the time course of osmotic haemolysis registered spectrophotometrically it has been described more comprehensively the membrane stabilizing effect of biological active substances. Extent and time course of osmotic haemolysis can be varied after the influence of any stabilizing drugs in different patterns. Both substances, IMET 3393 (γ-[1-methyl-5-bis- (β-chloraethyl) -amino-benzimidazol- (2)] -butyric acid · HCl) and IMET 3164 (β- [1-phenyl-5-bis- (β-chloraethyl) -amino-benzimidazolyl- (2)] -DL-alanine), respectively, i.p. applicated have increased the osmotic resistance and have delayed also the haemolysis of red blood cells in mice. The method was proved in vitro by chlorpromazine. This agent, however, has alterated only the resistance of erythrocytes but the parameter “t” was not influenced.

ZIMET 3164 inhibited the growth of sarcoma 180 P, sarcoma 180 G, and Walker 256 carcinosarcoma, but was unable to prolong the survival time of mice bearing Ehrlich ascites carcinoma or the leukaemias L 1210 and LAJ I to a worthwhile extent. The primary and secondary haemagglutinin formation to xenogenic red blood cells and immunological memory were significantly suppressed in mice. The drug exerted maximum effect when given on days −2 to +2 relative to antigenic stimulus. Administration exclusively prior to immunization induced only moderate immunosuppression while injection afterwards failed to affect the primary response at all, suggesting that the drug interferes with the afferent limb of immune response. In general, ZIMET 3164 proved to be half as effective as cyclophosphamide, but more effective than chlorambucil.

Intranasal (i. n.) infection with 10 LD50 of Sindbis virus caused acute encephalomyelitis and death in ABD2F1 mice 3-7 days post infection (p.i.). Histologic lesions were found in the CNS, pancreas. liver, parotid glands, exorbital lacrimal glands, lymphoid organs and kidneys. Repeated oral administration of the anticholinergic anti-Parkinson drug Norakin protected infected animals from death in a dose-dependent manner when treatment was started prior to but not after virus inoculation. The maximum protective effect was achieved when the drug was administered twice daily at doses of 2.5 or 5.0 mg/kg body mass for at least 56 hr; single injections of the full daily dose were ineffective. Daily doses of greater than or equal to 25 mg/kg body mass had a reduced protective effect or failed to prevent mortality. Administration of Norakin up to doses of 300 mg/kg body mass per day to noninfected ABD2F1 mice were tolerated without obvious clinical or histological signs of illness over a period of 104 hr. Replication of sindbis virus in BHK 21/C13 cells was not inhibited by Norakin concentrations up to 10 micrograms/ml. In Mengo virus-infected mice Norakin did not exert any protective effect within the range of 1.25-50.0 mg/kg body mass when treatment started 1 hr before infection and has been continued twice daily over a period of 104 hr.

After daily administration of 1 mg/kg over a period of 4 weeks, hirudin did not influence growth and general behaviour of the animals. There was no indication of treatment-related effects on the liver and the kidneys, on number and function of thrombocytes, on number and differentiation of white cells or on the erythrocytic system. Haemorrhagic complications did not occur. Formation of antibodies was not detectable. Histopathological changes due to application of r-hirudin were not found. LD50 is greater than 50 mg/kg body weight for intravenous application.

Turimycin is characterised by low acute toxicity. Mean lethal doses for mouse and rat are 750 mg/kg body weight for intraperitoneal application of something in excess of 3,000 mg/kg for oral administration. The blood pressure of anaesthetised cats may be reduced by amounts depending on intravenous Turimycin doses (between 10 and 50 mg/kg). The hypotensive effect of Turimycin is attributable to its negative inotropic effect on the heart and its spasmolytic action on the unstriated muscles. Reversible reduction of urine and ion excretion of rat following intraperitoneal application of 50 mg/kg body weight of Turimycin is interpreted as a consequence of such action upon blood pressure. A preliminary study was conducted into dogs which had orally received daily Turimycin doses of 50 or 125 mg/kg body weight over twelve months. No substance-depending functional or morphological damage was recorded.

After single i.v. administration of cis-diammine-platinum(II)-lactate cis-diammine-platinum(II)-lactate, L cis-diammine-platinum(II)-dilactate trans-dihydroxy-cis-dichlorodiammine-platinum(IV), the LD50 values have been calculated to range between 80 and 130 mg/kg in mice, and between 22 and 45 mg/kg in rats. The LD50 of cis-DDP amounted to 17 mg/kg and 6.6 mg/kg, respectively. Likewise, the compounds have been found to be about 3 to 5 times less toxic than the standard cis-DDP when administered daily for 5 consecutive days. Since the kidneys, the bone marrow, the lymphatic tissue and the intestinal tract have been proved to be the main target organs, the profile of the toxic action of the Pt(II)-complexes seems to be similar to that of cis-DDP. Additionally, the Pt(IV) compound has been found to be toxic to the pancreas, the liver and the salivary glands. With regard to the antineoplastic activity the more soluble lactates of cis-DDP showed a smaller therapeutic index compared to cis-DDP.

The effects on peritoneal macrophages of some chemotherapeutic agents administered subcutaneously to conventional male AB/Jena mice were studied. beta-[1-ethyl-(5-bis-(beta-chloroethyl)-aminobenzimidazolyl-(2)]-DL-alanine (IMET 2925), beta-[1-phenyl-5-bis-(beta-chloroethyl)-amino-benzimidazolyl-(2)]-DL-alanine (IMET 3164), and gamma-[1-phenyl-5-bis-(beta-chloroethyl)-amino-benzimidazolyl-(2)]-butyric acid (IMET 37/70) evoked a pronounced variation of the cell surface consisting in a shortening, coarsening and reduction in number of the microvili and other projections. Likewise, 1.3-bis(piperidinomethyl)-5-ethyl-5-phenyl-barbituric acid induced a flattening of the surface, but the structures appeared to be increased in number per area. Chlorambucil, 6-mercaptopurine, and 5-fluoro-uracil failed to provoke any obvious change in the threedimensional cell surface structure. These morphological findings are consistent with functional results reported previously.

Three spontaneous lymphomas of 23- to 24-month-old (AB/Jena X DBA/2 Jena)F1 females were serially transplanted into syngeneic hosts. They were histologically classified as malignant lymphoblastic lymphomas (ABDt2 and ABDt5) and as a malignant lymphoma of histiocytic type (ABDt6). All lymphomas disseminated into the liver, spleen, and pancreas, whereas ABDt2 and ABDt5 additionally infiltrated the bone marrow and leptomeninx. None of the tumors showed a leukemic growth form, but extreme granulocytosis was observed in leukemia P388-bearing mice. Since the lymphomas ABDt2 and ABDt5 expressed T-cell differentiation antigens Ly-1, Ly-2, and Ly-3, they are thought to be of T-cell origin. On the contrary to the lymphocytes of parental mouse strain ABDt2 and ABDt5 cells reacted with anti H-2.23 allosera. All tumors have been found to be sensitive to at least 5/7 clinically used anticancer drugs. But only ABDt2- and P388-bearing mice survived longer than 60 days after treatment with the potent anticancer drug 1,4-benzoquinone-guanylhydrazone-thiosemicarbazone (ambazone). Successful chemotherapy of both tumors was accompanied with resistance of the hosts against the second transplant of the same tumor. Summarizing the characteristics of the newly established transplantation tumors it is concluded that they can be recommended as screening models in the search for new antineoplastic agents.

Four newly synthesized estra-l,3,5(10)-triene-derivatives1, 3-methoxy-17α-cyanomethyl-estra-l,3,5(10)-triene-17β-ol (I), 3-methoxy-17α-rhodanomethyl-estra-l,3,5(10)-triene-17β-ol-tetrahydropyranylether (II), 17/8-(N2032,N2032-dimethylhydrazinocarbonyloxy)-estra-l,3,5(10)-triene-3β-ol (III), 3-methoxy-17-(N-phenylaminocarbonyloxy)-estra-l,3,5(10)-triene (IV), were studied in subchronic toxicity tests in female rats. The drugs were given orally and compared to mestranol (V) which was used as a reference. Special histopathologic examination was performed in each rat with respect to pituitary morphology. Different pituitary responses to the applied estrogens were found with regard to hyperplasia of the adenohypophysis and interstitial haemosiderosis: 17β-hydroxy-17α-alkylsubstituted derivatives (I, II, V) were less effective than 17β-carbamyloxy-derivatives (III, IV). These findings may be related to differences in pituitary accumulation of the investigated compounds, indicating any disposition-effect-relationships.

The enzymatic hydrolysis of fluoresceindiacetate (FDA) and the intracellular accumulation of fluorescein (fluorochromasia) by murine peritoneal macrophages were photometrically measured in cell suspensions. The intensity of fluorescence (excitation at lambda = 485 nm) was recorded by a right angel detector as a function of time, number of cells per ml, and FDA concentration, respectively. The meter response was found to be directly proportional up to the concentration of the fluorophor of 1.125 x 10(-6) M. In suspension the intensity caused by cells other than macrophages could be neglected. The rate of the fluorescein formation corresponds to the Michaelis-Menten constants (km = 8,34 x 10(-6) M.) Repeated in vivo administrations of some N-mustard benzimidazole derivatives were followed by competitive and non-competitive inhibition of the FDA-hydrolysis, respectively. Consequently, the fluorescence intensity varied, but without an concomitant adequate alteration of the non-specific (alpha-naphthyl acetate) esterase as was being measured by means of photometry of single macrophages in cell smears. Thus, this method seems to be suitable for quantitation of membrane (permeability) alteration induced experimentelly in macrophages.

In acute toxicity studies the maximum tolerated dose (MTD), the LD50 and the LD100 of Bendamustin were determined in rats and mice after i.v. and oral administration. In a subchronic study male rats were given Bendamustin for 28 days at oral dose levels of 5, 10, 20 or 40 mg/kg/day. Chlorambucil was used as a standard at dose levels of 1, 5 and 10 mg/kg/day. Bodyweight gain, food and water intake, hematology, clinical chemistry and histopathology were evaluated. With quantitative differences the main target organs for both compounds were the bone marrow, the kidney, the intestine and the lymphatic system. Additionally, Chlorambucil caused a significant atrophy of the testes and a slight atrophy of the pancreas at a dose of 5 mg/kg/day. In conclusion, the data obtained may be used as a base to evaluate the therapeutic range of Bendamustin compared to Chlorambucil for the oral route.

Experiences with the three step teratological screening test for selection of teratogenic side effects are described.

A mathematical model of the pathogenesis of experimental Mengo virus infection in mice has been developed and fitted using kinetic data of both virus multiplication in different organs and mortality. The behaviour of the model proved to be bistable. In contrast to the widely accepted hypothesis that an acutely virus-infected host dies when virus replication has attained a critical level in the main target organ, the present results showed the following: the maximum virus titre in brain, the main target organ, has been reached already 24 hr post infection (p.i.) but the animals began to die since 60 hr. Hence, it was postulated and confirmed by a good model fit to the experimental data that the so-called AUC (area under the curve) of the virus multiplication kinetics may be a critical quantity. From this finding a hypothesis was deduced assuming that in the presence of high amounts of the virus the antiviral effect of IFN wanes with time. Since this process accounts for death, it may be a potential target of antiviral therapy.

The cardiotoxic and myelosuppressive effects of the potential antitumor antibiotics violamycin BI (VBI) and violamycin BII (VBII) were studied in rats in comparison with daunorubicin (DAU), doxorubicin (ADR) and carminomycin (CAR). Rats were intravenously given the compounds 10 times for three weeks at total doses of 0.4 to 3 times of the acute LD50. Cardiac toxicity was measured using ECG (widening of the QRS complex), and screening parameters for bone marrow suppression were white blood cell counts, hematocrit and hemoglobin values. Following the drug injections the myocardium and the bone marrow were additionally investigated by light microscopy. With the exception of ADR, all the anthracyclines tested showed a more or less strong dissociation of cardiotoxic and myelotoxic activities. VBI was found to be only toxic on the heart but not on the bone marrow, whereas DAU, VBII and CAR were predominantly toxic on the bone marrow. Only ADR showed strong cardiac toxicity as well as distinct myelosuppression. A final evaluation of VBI and VBII has to include both the antineoplastic and the toxic properties of the compounds.

The influence of increasing doses of various potentially antiviral agents on Mengo virus-and Sindbis virus-infected mice was assessed determining death rates and histologic lesions. All drugs given in abundance showed dose-dependent decrease of antiviral activity following the maximum protective effects in either animal model. From the toxicological point of view the antiviral agents in question could be classified into two groups. High doses of tilorone hydrochloride or 10-carboxymethyl-9-acridanone produced toxic effects in both uninfected and virus-infected animals. In contrast, high doses of quercetin, double-stranded ribonucleic acid (dsRNA), 1-ethylisatin-S-n-butylisothiosemicarbazone or Norakin induced no obvious drug-mediated histologic alterations either in uninfected or in virus-infected individuals, but exerted a decreased protection in virus-infected animals. It is suggested that high doses of the compounds of second group adversely affect early host defence in both Mengo virus and Sindbis virus-infected mice.

Experiences with the three step teratological screening test for selection of teratogenic side effects are described. Step I: The prenatal examination of the foetuses may give indications of embryotoxicity, growth retardation and teratogenicity. Step II: The peri- and postnatal examination includes the duration of pregnancy, the delivery, the viability, the postnatal development and behaviour of the untreated offspring. In special cases the transplacental tumour induction may be studied. Step III: The fertility of the untreated offspring is examined and, in some cases, the generation test should be added.

Beta-[1-Phenyl-5-bis(beta-chloroethyl)-amino-benzimidazolyl-(2)]-DL-alanin (ZIMET 3164), a highly immunosuppressive but moderately cytostatic agent, was found to be able to prevent the progression of spontaneous murine immune complex nephritis in a dose-dependent fashion. For experiments, BCG-stimulated conventional female (NMRI X NZB)F1 mice suffering from rapidly progressive nephritis, BCG-stimulated and unilaterally nephrectomized (NMRI X NZB)F1 females, and (AB/Jena X NZB)F1 females characterized by a prolonged course of the disease were used. The beneficial effect was quantified by fluorescence photometry and histometry, and semiquantitatively detected by estimation of the extent of damage of individual glomerular structures when histometric methods were unsuited. Treatment of young adult animals characterized by slight to moderate glomerular lesions was more effective than of older ones with advanced nephritis. At equi-immunosuppressive dose levels ZIMET 3164 was about twice as effective as the reference substance cyclophosphamide.

Isolated atria of guinea-pigs showed negative inotropic and negative chronotropic responses after violamycin B I (V), carminomycin (C) and daunomycin (D), respectively. The mean effective concentrations in reducing amplitude (IC50) were 5.9 x 10(-4) mol x 1(-1) for V and 1.3 x 10(-4) mol x 1(-1) for C and D. In rabbits, intravenous injections of different doses of the antibiotics twice weekly for one month produced histopathological alterations in the myocardial tissue, which were smaller after D than after C or V.

Female and male beagle dogs were administered orally STS 557 (17 alpha-cyanomethyl-17 beta-hydroxy-13 beta-methyl-gon-4,9(10)-dien-3-one) for 6 months at dose levels of 0.01, 0.1, or 1.0 mg/kg/day, and levonorgestrel at a dose of 1.0 mg/kg/day, respectively. The results mainly confirmed the gestagenic efficacy on the reproductive organs of both compounds acting directly or via the anterior pituitary gland. In contrast to levonorgestrel, STS 557 did not show any androgenic activity, but had slightly estrogenic effects. Neither clinical, functional nor morphological investigations revealed toxic side effects of the drugs on the liver, the kidneys, the bone marrow, or on blood clotting function.