Absence of a direct anabolic effect of 17 beta-estradiol on normal human bone marrow stromal cells

The effects of 17 beta-estradiol on the proliferation and differentiation of cultured normal human bone marrow stromal cells were investigated. Treatment of 17 beta-estradiol at the concentration of 10(-6) approximately 10(-10) M for either 48 hours or 7 days did not affect [3H] thymidine incorporation. 17 beta-estradiol (10(-8)M) treatment for 4 or 7 days also failed to stimulate alkaline phosphatase activity. Similarly, incubation with 17 beta-estradiol (10(-8) M) for 48 hours did not increase the incorporation of [3H] proline into collagenase digestible protein and noncollagen proteins and secretion of IGF-I and IGF binding proteins in human bone marrow stromal cells. Present data indicate that 17 beta-estradiol does not have a direct effect on cultured normal human bone marrow stromal cells. With previous findings that estradiol elicits few effects on normal human osteoblasts, our results strongly suggest that estrogen does not have a direct anabolic effect on normal human osteoblast lineage. Therefore, the in vivo estrogen effects may be entirely through an antiresorptive mechanism or, if any anabolic role of estrogen is present, it must be indirect and mediated by other hormones or local factors.

The thrombolytic effect of lumbrokinase is not as potent as urokinase in a rabbit cerebral embolism model

The purpose of the present study is to determine whether lumbrokinase has an in vivo thrombolytic effect in a rabbit cerebral embolism model. In our previous studies, we found that lumbrokinase, an extract from Korean earth worms, has a strong in vitro fibrinolytic effect without the presence of plasminogen and significant in vivo thrombolytic effects of lumbrokinase in a rat human-clot-induced cerebral embolism model. We established the cerebral embolism model in rabbits by injecting a piece of human clot into the internal carotid artery via the external carotid artery and confirmed the occlusion with angiography. Twenty one rabbits were divided into three groups and 5cc of saline, urokinase of 50,000 u/ml, and equipotent LK were injected intraarterially for 30 minutes into each group of 7 animals. Ten minutes after the end of infusion, an angiogram was performed to confirm the recanalization. Clot lysis occurred in one, six, and one animals in the saline, urokinase and lumbrokinase treated groups respectively. With regard to its in vitro effect, lumbrokinase is not as potent in vivo. Further investigation should be performed to determine the cause of its weakened in vivo effect and to develop a method to potentiate it.

A case of osteomalacia: the pivotal role of the non-decalcified bone biopsy

A postmenopausal osteopenic woman presented with recurrent stress fractures of the feet and normal parameters of mineral homeostasis. Despite the absence of biochemical or radiographic evidence, severe osteomalacia was documented by histomorphometric analysis of a tetracycline labeled, non-decalcified bone biopsy. This observation underscores the need for specific bone biopsy confirmation of skeletal disease in patients with fracture-prone osteopenia.

A melanocyte-specific complementary DNA clone whose expression is inducible by melanotropin and isobutylmethyl xanthine

Two groups of cDNA clones were isolated by screening a lambda gt11 cDNA library of normal human melanocytes with antityrosinase antibodies: one group of 13 was related to the human tyrosinase gene. The properties of the other group of three cDNA clones was investigated by the use of a representative clone, Pmel 17-1. The cDNA hybridized to an mRNA species of approximately 2600 bases from human and murine melanocytes. The transcript of Pmel 17-1 (17-1 mRNA) was expressed preferentially in melanocytes and its abundance paralleled the melanin content. The expression of Pmel 17-1 mRNA increased after stimulation of human and murine melanoma cells with agents that increase the levels of melanization. Immunocompetition assays with monoclonal antibodies to gp75, a known pigmentation-associated antigen of melanocytes, suggested that Pmel 17-1 encodes a 75,000 Mr glycoprotein that is highly abundant in melanotic cells and shares some immunological homology with tyrosinase. The gene for Pmel 17-1 did not map at or near the c-albino locus in mice. The cDNA of Pmel 17-1 detected a single hybridizing restriction fragment in both human and murine DNA, indicating that the gene has been conserved between these two species and exists as a single gene in each.

Isolation and initial characterization of multiple species of T-lymphocyte subset cDNA clones

A modified differential screening procedure was applied to analyze cDNA libraries of cloned helper T lymphocytes (Th) and cytolytic T lymphocytes (CTL). Negative and positive differential screening and RNA blot analysis were used to identify cDNA clones that were expressed preferentially in Th or CTL. Seven clones corresponded to previously described T-cell genes, and 16 additional types of cDNA clones were isolated, 9 from Th and 7 from CTL. Of these, 3 were expressed in both Th and CTL, 7 were expressed in only Th, and 6 only in CTL. These clones were analyzed for induction after stimulation by interleukin 2 or Con A or after stimulation of the T-cell antigen receptor (TCR). Three different patterns of expression were seen: induction only by Con A, induction by Con A and interleukin 2, and induction by Con A and TCR stimulation. The approach is potentially useful for analyzing paths of T-cell differentiation and detecting cDNA clones encoding unrecognized cytokines.

Tibial bowing exacerbated by partial premature epiphyseal closure in sex-linked hypophosphatemic rickets

Two girls with sex-linked hypophosphatemic rickets are described in whom premature fusion of the medial proximal tibial epiphyseal plate exacerbated lower-extremity bowing. Early recognition of this complication and appropriate surgical intervention--excision of the bony bridge in the growth plate, or epiphysiodesis of the still open portion of the growth plate--might prevent further shortening or deformity of the affected limb.

Audiologic findings in young patients with hypophosphatemic bone disease

Audiometric tests were conducted on 19 subjects with hypophosphatemic bone disease to investigate whether auditory impairment like that reported in affected adults occurs in young patients. No hearing loss or significant auditory findings were noted among the children or young adult patients. However, sensorineural hearing loss of cochlear origin was identified in the three oldest subjects (40 to 58 years), although a history of noise exposure in two of them could explain the observations. The results indicate that if an association exists between hypophosphatemic bone disease and hearing impairment, the auditory signs will not develop until adulthood in treated patients. Additional studies of large populations of affected adults are needed to identify the incidence and mechanism(s) of the auditory system abnormalities and to assess any effect of medical therapy for the metabolic bone disease.

Diurnal variation of serum calcium and phosphorus in postmenopausal women

Serum calcium, ionized calcium, and phosphorus have been obtained at hourly intervals in nine healthy postmenopausal women. The hourly means of ionized calcium and phosphorus demonstrate significant diurnal variation with a similar apogee, nadir, and periodicity (24 hours). These results are distinct from the diurnal variation of ionized calcium and phosphorus previously reported for young men and provide more evidence of an altered mineral hemostasis in postmenopausal women.

Intermittent radiographic changes of rickets without defective trabecular bone mineralization in a case of spondylometaphyseal dysplasia

Although a variety of metaphyseal and spondylometaphyseal dysplasias have been identified, the natural course of the skeletal defects in these disorders has not been well characterized. We describe an 8-year-old girl with spondylometaphyseal dysplasia, most closely resembling the Kozlowski type, in whom rachitic metaphyseal involvement underwent dramatic radiographic healing when she wore leg braces; discontinuation of the braces was followed by recurrence of the growth plate abnormalities. A generalized disturbance in mineral metabolism or skeletal remodeling to explain these radiographic changes was excluded by extensive biochemical studies and histologic examination of an undecalcified iliac crest specimen. Our observations suggest that the defect in endochondral bone formation in the spondylometaphyseal dysplasias may be responsive to mechanical factors and that interventions that alter stress and strain on the skeleton, such as immobilization or use of orthopedic braces, may considerably modify the radiographic appearance of the growth plate disturbance.

Fasting modulates creatine entry into skeletal muscle in the mouse

[14C]-Creatine entry into skeletal muscle of mice is inhibited by feeding creatine or by fasting. Plasma creatine specific activity after an i.p. injection of [14C]-creatine is decreased by feeding creatine and increased by fasting. These results indicate that creatine enters muscle via a saturable process that is modulated by fasting.