Molecular analysis of a case of Philadelphia chromosome-positive acute myeloid leukemia

This report describes a precise molecular analysis of a rare case of Philadelphia chromosome (Ph) positive acute myeloid leukemia (AML) (FAB classification M2). Phenotypic markers were positive for cells of the myeloid lineage, but negative for B cell and T cell lineage. The leukemic cells carried a Philadelphia chromosome. Major breakpoint cluster region (M-BCR) rearrangement was detected by the Southern blot analysis. Reverse transcriptase polymerase chain reaction analysis revealed the presence of b3a2 BCR/ABL mRNA transcripts. The patient achieved complete remission by conventional remission induction therapy for acute myeloid leukemia. M-BCR rearrangement could not be detected during complete remission. After hematological remission of an 8-month duration, the patient relapsed and died of respiratory distress due to pneumonia. Our case indicate Ph-positive AML with M-BCR rearrangement actually exists. Ph-positive AML carries either M-BCR rearrangement expressing the P210 BCR-ABL or minor breakpoint cluster region (m-BCR) rearrangement producing the P190 BCR-ABL. Therefore, additional other factor (s) apart from the Ph chromosome must be responsible for the acute malignant transformation.

White dot fovea

PURPOSE

To describe a newly identified clinical entity tentatively named white dot fovea.

METHODS

We examined by scanning laser ophthalmoscopy 58 eyes of 30 patients (mean age, 64 years) who had white dots in the fovea (anatomically defined as the foveola) simulating macular hole. In addition, the retinal surfaces of 30 autopsy eyes from donors aged 70 years or older were observed by scanning electron microscopy.

RESULTS

White dot fovea was bilateral in 28 of 30 patients (93%). It was characterized by the presence of numerous white dots on the foveal surface distributed either diffusely or along the foveal margin, forming a gray ring. There was no subjective symptom or visual disturbance. The condition was best seen by a scanning laser ophthalmoscope using argon blue laser as the light source. The white dots numbered from 100 to 300 per eye. Each dot was approximately 5 microns in diameter. Scanning electron microscopy showed foveal granules simulating the white dots in five of 30 autopsy eyes (17%). The granules had multiple protrusions with cilia-like structures resembling glial cells. This glia-like structure seemed to be a counterpart of clinically observed white dot fovea.

CONCLUSION

White dot fovea is a new, frequent, and apparently innocuous clinical entity. It merits due attention in the differential diagnosis of macular holes.

Characterization of zinc effect to inhibit osteoclast-like cell formation in mouse marrow culture: interaction with dexamethasone

The inhibitory effect of zinc compounds on osteoclast-like cell formation in mouse marrow culture in vitro was characterized. The bone marrow cells were cultured for 7 days in alpha-minimal essential medium containing a well-known bone resorbing agent, 1,25-dihydroxyvitamin D3[1,25(OH)2D3] or prostaglandin E2 (PGE2). Osteoclast-like cell formation was estimated by staining for tartrate-resistant acid phosphatase (TRACP), a marker enzyme of osteoclasts. The presence of 1,25(OH)2D3 (10(-8) M) or PGE2 (10(-6) M) induced a remarkable increase in osteoclast-like multinucleated cells. These increases were enhanced by the presence of dexamethasone (10(-9) to 10(-6) M). The dexamethasone (10(-7) M)-enhanced osteoclast-like cell formation was not inhibited by the presence of zinc sulfate (10(-6) M) or zinc-chelating dipeptide (beta-alanyl-L-histidinato zinc; 10(-6) M), although the zinc compounds had an inhibitory effect on osteoclastic formation in the absence of the steroid. The effect of dexamethasone was not seen, when the steroid was added at the later stage of culture with bone-resorbing agents. In this case, the inhibitory effect of zinc compounds was clearly revealed. This effect of zinc compounds disappeared in the presence of Ca2+-chelating agent (0.5 mM EGTA). The present study suggests that zinc compounds have an inhibitory effect at the stage of differentiation of preosteoclastic cells in bone marrow cell culture system.

Ciliary detachment after retinal detachment surgery

PURPOSE

To evaluate the changes in the ciliary body and anterior choroid that occur after retinal detachment surgery.

METHODS

Thirty-three eyes with rhegmatogenous retinal detachment were evaluated before and after surgery. An ultrasound biomicroscope was used to observe the ciliary body and anterior choroid.

RESULTS

Ciliary detachment was found to be present in 22 eyes (67%) on examination 5-14 days after surgery. The detachment was confined to the pars plana in nine eyes and involved the pars plicata and plana in 13 eyes. The whole circumference of the ciliary body was detached in seven of the 13 eyes. In three of these seven eyes, ophthalmoscopy showed the detachment to extend to the anterior choroid. Ciliary detachment lasted for at least 2 weeks and resolved within 2 months in 19 of 22 eyes. A shallow anterior chamber was observed after surgery in 12 eyes with severe ciliary detachment. Ciliary detachment was more likely to occur in eyes with a large retinal tear, large area of scleral buckling, or in eyes that were treated with solid silicone exoplant.

CONCLUSION

Ciliary detachment occurred frequently after retinal detachment surgery using scleral buckling. It was temporary and usually did not result in untoward complications.

A multiple gastric ulcer case caused by cytomegalovirus infection

The patient was a 31 year old male complaining discomfort in the epigastrium. Endoscopy of the upper gastrointestinal tract indicated multiple gastric ulcers. Biopsy specimen taken from the ulcerous region indicated giant cells accompanying intranuclear inclusion bodies in the gastric mucosa. Since the patient tested positive to cytomegalovirus (CMV)-IgM antibody, he was assumed to have gastric ulcers caused by CMV infection. However, the patient was cured without the administration of antiviral agent because no definite immunodeficiency status was observed. The result of present study indicated that endoscopic biopsy is useful for diagnosing gastrointestinal lesion attributable to CMW infection.

The role of the premacular liquefied pocket and premacular vitreous cortex in idiopathic macular hole development

PURPOSE

To clarify the role of the vitreous in idiopathic macular hole formation.

METHODS

We prospectively evaluated the vitreous before and during vitreous surgery in 64 consecutive eyes of 62 patients (stage 1B, four eyes; stage 2, ten eyes; stage 3, 43 eyes; stage 4, four eyes) with macular holes; another three eyes underwent a second vitrectomy. After core vitrectomy, the premacular vitreous cortex was examined by applying gentle suction. The detached posterior hyaloid face was observed under endoilluminiation.

RESULTS

We observed in all eyes a liquefied lacuna anterior to the posterior fundus before and during vitreous surgery. The premacular vitreous cortex was extremely thin and elastic upon gentle suction. A premacular ring, the diameter two to four times that of the Weiss ring, was observed in 48 of 57 eyes (84%) with stages 1B, 2, and 3 macular hole. In most cases, the vitreous cortex within the premacular ring either was absent or had a break, resulting in a premacular round defect. The vitreous cortex peripheral to the premacular ring, which was thick and less deformed, never showed a break. In eyes that had undergone a second vitrectomy, we noted residual cortex or an epiretinal membrane around the macular hole.

CONCLUSIONS

The premacular vitreous cortex is extremely thin and elastic. It is sharply demarcated by a ring from the thick peripheral vitreous cortex. Tangential traction, which causes macular holes, appears to originate exclusively in the premacular vitreous cortex that forms the posterior wall of the premacular liquefied pocket.

[Programmed thymic T cell death and negative selection via Fas and TCR/CD3 complex]

In the immune system of thymic microenvironment, immature T cells are selected by T cell receptor (TCR)-mediated antigen stimulation and most of thymic T cells die by apoptosis. Molecular mechanism for the elimination of autoreactive T cells by apoptotic cell death in thymus is almost unknown, though a differential avidity model for TCR-mediated selection is recently proposed. On the other hand, Fas antigen (Fas), which is apoptosis inducing cell surface receptor, is expressed on antigen stimulated human thymocytes and involved in superantigen-induced negative selection. Recent studies have suggested that CD30 and CD40 ligand (gp39) on thymocytes is also involved in a part of negative selection. Thus, it is likely that the process of negative selection may involve multiple, and to some extent redundant, costimulation signals.

Zinc compounds inhibit osteoclast-like cell formation at the earlier stage of rat marrow culture but not osteoclast function

The effect of zinc compounds on osteoclast-like cell formation in rat marrow culture in vitro was investigated. The bone marrow cells were cultured for 7 days in alpha-minimal essential medium containing a well-known bone resorbing hormone (1, 25-dihydroxyvitamin D3 and parathyroid hormone [1-34]). Osteoclast-like cell formation was estimated by staining for tartrate-resistant acid phosphatase (TRACP), a marker enzyme of osteoclasts. The presence of 1, 25-dihydroxyvitamin D3 (10(-8) M) or parathyroid hormone (PTH; 10(-8) M) induced a remarkable increase in osteoclast-like multinucleated cells (MNC). These increases were clearly inhibited by the presence of zinc sulfate or zinc-chelating dipeptide (beta-alanyl-L-histidinato zinc; AHZ) in the concentration range of 10(-7) to 10(-5) M. The inhibitory effect was seen at the earlier stage of osteoclast-like MNC formation. However, zinc compounds (10(-6) M) did not have an effect on PTH (10(-8) M)-induced osteoclast-like cell formation in the presence of EGTA (5 x 10(-4) M), dibucaine (10(-5) M) or staurosporine (10(-9) M). Moreover, when osteoclasts isolated from rat femoral-diaphyseal tissues were cultured for 24 h in the presence of zinc compounds (10(-7) to 10(-5) M), the compounds did not have an effect on cell numbers or lysosomal enzymes activity (acid phosphatase and beta-glucuronidase) in the cells. The present study clearly demonstrates that zinc compounds inhibit osteoclast-like cell formation at the earlier stage with differentiation of marrow cells.

Watershed zone in the human peripheral choroid

PURPOSE

To evaluate the angioarchitecture and the hemodynamics in the peripheral choroid in humans.

METHODS

Choroidal circulation was examined in 23 normal eyes and in 7 with equatorial lattice degeneration by wide-angle indocyanine green (ICG) angiography using a scanning laser ophthalmoscope. A hand-held 30-diopter lens was placed in front of the eye to expand the observation angle from the original 40 degrees to 70 degrees. The peripheral temporal choroid and the ora serrata thus could be seen in one frame.

RESULTS

An arterial watershed zone was identified in the temporal peripheral choroid in 21 of 30 eyes. This watershed zone was located in a sectorial region posterior to the ora serrata. It did not form a circular belt along the equator. The area anterior to the watershed zone was supplied by peripheral retrograde choroidal arteries. Inflow of dye into the peripheral retrograde choroidal arteries was consistently later than into the more posterior choroid via short posterior ciliary arteries. The terminal branches of peripheral and short posterior ciliary arteries did not form functional anastomoses. Peripheral retrograde choroidal arteries showed wide variations in number and distribution. These arteries originated from recurrent branches of long posterior ciliary arteries in 18 of 21 eyes and from anterior ciliary arteries in 3 eyes. There was no correlation between the watershed zone and equatorial lattice degeneration in location and extent.

CONCLUSION

A peripheral watershed zone is a regular feature in the far temporal sector of the choroid. The far peripheral choroid anterior to the watershed zone was perfused by peripheral retrograde choroidal arteries which originated from the long posterior ciliary arteries and/or the anterior ciliary arteries.

Tractional elevation of Henle's fiber layer in idiopathic macular holes

PURPOSE

We sought to clarify the morphologic features of macular hole development.

METHODS

Using scanning laser ophthalmoscopy, we examined 47 eyes with macular holes before and after vitrectomy. Cases included three eyes with stage 1B disease (foveal detachment), 14 with stage 2 (break at the fovea), 21 with stage 3 (full-thickness macular hole), and nine with stage 4 (detached operculum), according to Gass's classification. Ten eyes with central serous chorioretinopathy served as controls.

RESULTS

Radiating striae of Henle's fibers were seen around the elevated rim of the macular cyst or hole when the intraretinal structures were illuminated by helium-neon laser. Granularity was observed on the macular hole floor. A granular reflex corresponding to the macular break or hole, but no radiating striae were seen by argon blue laser. In 40 eyes in which macular holes were successfully closed by vitrectomy, radiating striae of Henle's fiber layer disappeared, and the normal foveal depression was restored. The ten eyes with central serous chorioretinopathy had a normal foveolar depression and no detectable radiating striae of Henle's fiber layer, despite full-thickness retinal detachment in the macular area.

CONCLUSIONS

Tractional elevation of Henle's fiber layer with intraretinal foveolar cyst formation is the initial feature of macular hole development. A macular hole is formed when the anterior cyst wall containing Henle's fiber layer is operculated. Remnants of the photoreceptor cell layer remain on the hole floor in the early stage of macular hole development and subsequently degenerate.

Subsequent epilepsy in very-low-birthweight infants: a long-term follow-up study from birth

We studied 197 survivors of 290 very-low-birthweight (VLBW, < 1,500 g) infants admitted to our neonatal intensive care unit from 1977 through 1982. The children were all followed until at least age 6 years (mean 10 years 6 months). Eight children (4.1%) had epilepsy: 5 had generalized, 2 had unilateral, and 1 had partial seizures. Two (1.0%) had active and poorly controlled epilepsy. Three had a history of epileptic seizures, but none for > or = 6 years, and 3 were no longer receiving antiepileptic drug (AED) treatment. Most (5 of 8) were severely multiply handicapped. As compared with VLBW children without epileptic seizures and neurodevelopmental abnormalities, VLBW children with epileptic seizures had a gestational age < 27 weeks, a weight < 1,000 g, severe perinatal complications as indicated by an Apgar score of < 4 at 5 min, and the need for long-term oxygen administration.

Infrared angiography of the anterior ocular segment

We performed angiography with indocyanine green (ICG) and fluorescein using a scanning laser ophthalmoscope (SLO) in the anterior segments of seven normal and 35 diseased eyes. ICG angiography revealed the radical stromal vessels and minor arterial circle in brown irides, which were not detected by fluorescein angiography. High penetration of infrared fluorescence through the pigmented tissue and absence of extravasation of ICG facilitated demonstration of the fine structure of iris rubeosis and its origins from stromal vessels. In 11 diabetic eyes, the iris rubeosis showed three basic patterns of location: along the pupillary margin; originating from the iris root; and arising from stromal radial vessels near the collarette. ICG gonioangiography with SLO showed fine structure of angle rubeosis because of its high resolution and greater depth in focus. Rubeotic vessels in the chamber angle were perfused by neovascular trunks which arose from the iris root in all 12 rubeotic eyes. Rubeosis in the iris and the angle consistently showed no extravasation of the ICG dye, while fluorescein quickly leaked out. ICG angiography with SLO in the anterior ocular segment proved to be a useful means to study the structure and the hemodynamics of normal and newly formed vessels.

Inhibitory effect of zinc-chelating dipeptide on parathyroid hormone-stimulated osteoclast-like cell formation in mouse marrow cultures: involvement of calcium signaling

A possible mechanism of zinc action inhibiting the PTH-induced osteoclast-like cell formation in mouse marrow culture system in vitro was investigated. Bone marrow cells were cultured for 7 days in alpha-minimal essential medium containing a well-known bone-resorbing agent parathyroid hormone (1-34) (PTH). Osteoclast-like cell formation was estimated with staining for tartrate-resistant acid phosphatase (TRACP), a marker enzyme of osteoclasts. The effect of zinc sulfate (10(-6) M) or beta-alanyl-L-histidinato zinc (AHZ; 10(-6) M) inhibiting the PTH (10(-8) M)-induced osteoclast-like cell formation was clearly seen in the absence or presence of theophylline (10(-4) M). However, zinc compounds did not inhibit the stimulatory effect of dibutyryladenosine 3',5'-cyclic monophosphate (DBcAMP; 10(-4) M) on osteoclast-like cell formation. The stimulating effect of PTH (10(-8) M) on osteoclast-like cell formation was clearly weakened (about 50%) in the presence of EGTA (1.0 mM) or dibucaine (10(-5) M). Phorbol 12-myristate 13-acetate (PMA), a protein kinase C activator (10(-8) to 10(-6) M), clearly stimulated osteoclast-like cell formation. PMA effect was inhibited by the presence of AHZ (10(-6) M) or zinc sulfate (10(-8) M). However, the inhibitory effect of zinc compounds was not seen in the presence of both PTH (10(-8) M) and PMA (10(-6) M). The present findings suggest that zinc compounds inhibit PTH-stimulated osteoclast-like cell formation mediated through the Ca(2+)-dependent activation of protein kinase C.

Differential effects of transforming growth factor-beta on osteoclast-like cell formation in mouse marrow culture: relation to the effect of zinc-chelating dipeptides

The effect of transforming growth factor-beta (TGF-beta) on osteoclast-like cell formation in mouse marrow culture in vitro was investigated. The bone marrow cells were cultured for 7 days in alpha-minimal essential medium containing a well-known bone resorbing agent. Osteoclast-like cell formation was estimated with staining for tartrate-resistant acid phosphatase (TRACP), a marker enzyme of osteoclasts. The presence of TGF-beta (10(-13)-10(-11) M) caused a significant increase in the number of osteoclast-like multinucleated cells (MNCs); the maximum effect was seen with 10(-12) MTGF-beta. With a higher concentration (10(-10) M) of TGF-beta, the growth factor dramatically inhibited the 1,25-dihydroxyvitamin D5 [1,25(OH)2D3; 10(-8) M]-induced formation of osteoclast-like MNCs. This inhibitory effect was also seen in the formation of osteoclast-like MNCs stimulated by parathyroid hormone (10(-8) M), prostaglandine E2 (10(-6) M), and interleukin-1 alpha (50 U/ml). The stimulatory effect of TGF-beta (10(-12) M) on osteoclast-like MNCs formation was inhibited by zinc sulfate (10(-6) M) or zinc-chelating dipeptide [beta-alanyl-L-histidinato zinc (AHZ), 10(-6) M]. The stimulating effect of TGF-beta was markedly weakened by the presence of EGTA (0.5 mM), a chelator of Ca2+. The inhibitory effect of zinc compounds was not seen in the presence of EGTA. Moreover, the inhibitory effect of TGF-beta (10(-10) M), zinc sulfate (10(-6) M), or AHZ (10(-6) M) on osteoclast-like MNCs formation was not demonstrated in mature osteoclastic cells, although calcitonin (3 x 10(-8) M) significantly inhibited the osteoclastic formation. The present study demonstrates that TGF-beta has a stimulating and an inhibiting effect on osteoclast-like cell formation in mouse marrow culture, and that zinc can inhibit the stimulatory effect of TGF-beta.

Differential effects of insulin and insulin-like growth factor-I in the femoral tissues of rats with skeletal unloading

The alteration of bone metabolism in the femur of rats with skeletal unloading for 4 days was investigated. Skeletal unloading was designed using the model of hindlimb hang in rats. Skeletal unloading caused a significant decrease in femoral weight, calcium, and phosphorus contents in the metaphysis but not diaphysis. Also, the unloading induced a significant decrease of zinc content, alkaline phosphatase activity, and deoxyribonucleic acid (DNA) content in the femoral diaphysis and metaphysis. When the femoral-diaphyseal and metaphyseal tissues from normal and skeletal-unloading rats were cultured in the presence of insulin (10(-9) and 10(-8) M) for 24 hours in vitro, the hormonal effect to increase alkaline phosphatase activity and DNA content in the diaphysis, but not metaphysis, was lost in the bone tissues from unloading rats. However, the culture with insulin-like growth factor-I (IGF-I; 10(-8) and 10(-7) M) produced a significant increase of alkaline phosphatase activity and DNA content in both the diaphyseal and metaphyseal tissues from normal and unloading rats. These results demonstrate that skeletal unloading causes an impairment of insulin effect, but not IGF-I effect, on bone metabolism in femoral tissues.

Oval defect in detached posterior hyaloid membrane in idiopathic preretinal macular fibrosis

We examined the vitreous of 71 eyes with idiopathic preretinal macular fibrosis and observed complete posterior vitreous detachment in 48 eyes (68%), partial posterior vitreous detachment in 16 eyes (22%), and no posterior vitreous detachment in seven eyes (10%). Among the 48 eyes with posterior vitreous detachment, we observed that the detached posterior hyaloid membrane had an oval or round defect in 31 eyes (65%) and a break in the premacular area in 12 eyes (25%). The size and the contour of the premacular defects in the posterior hyaloid membrane corresponded to those characteristic of premacular fibrosis. A premacular oval defect in the detached posterior hyaloid membrane indicates that the vitreous cortex is a structural component of idiopathic premacular fibrosis. We postulate that the thin, premacular vitreous cortex, which forms the posterior wall of the premacular liquefied pocket, plays a key role in the development of idiopathic preretinal macular fibrosis in eyes with or without posterior vitreous detachment.

Inhibitory effect of zinc compounds on osteoclast-like cell formation in mouse marrow cultures

The effect of zinc compounds on osteoclast-like cell formation in mouse marrow culture in vitro was investigated. The bone marrow cells were cultured for 7 days in alpha-minimal essential medium containing a well-known bone resorbing agent [1,25-dihydroxyvitamin D3, parathyroid hormone (1-34), interleukin-1 alpha or prostaglandin E2]. Osteoclast-like cell formation was estimated by staining for tartrate-resistant acid phosphatase (TRACP), a marker enzyme of osteoclasts. The presence of 1,25-dihydroxyvitamin D3 (10(-8) M), parathyroid hormone (10(-8) M), interleukin-1 alpha (50 U/mL) or prostaglandin E2 (10(-6) M) induced a remarkable increase in osteoclast-like multinucleated cells. These increases were inhibited by the presence of zinc sulfate or zinc-chelating dipeptide (beta-alanyl-L-histidinato zinc; AHZ) in the concentration range of 10(-8) to 10(-5) M. The inhibitory effect of AHZ (10(-8) and 10(-7) M) was more intensive than that of zinc sulfate. Furthermore, the presence of Ni2+, Cu2+, Mn2+ or Co2+ (10(-7) and 10(-6) M) did not have an effect on parathyroid hormone (10(-8) M)-induced osteoclast-like cell formation. The present study clearly demonstrates that zinc compounds have a potent inhibitory effect on osteoclast-like cell formation in mouse marrow culture.

[Perforation of the right ventricular wall and extraction into the left thoracic cavity by a permanent endocardial pacemaker lead: a case report]

A 80-year-old woman with right ventricular wall perforation and extraction into the left thoracic cavity by a permanent endocardial pacemaker (PM) lead was presented. The patient underwent an insertion of a permanent endocardial lead into the apex of the right ventricle for the treatment of sick sinus syndrome. The right ventricular perforation of the PM lead was incidentally diagnosed by recognizing it into the left thoracic cavity three months after the operation. Another PM lead could be inserted without removal of the former one.

Histomorphological confirmation of the preventive effect of beta-alanyl-L-histidinato zinc on bone loss in ovariectomized rats

The effect of beta-alanyl-L-histidinato zinc (AHZ), in which zinc is chelated to beta-alanyl-L-histidine, on bone loss was investigated in the femur of ovariectomized rats. AHZ (10, 30 and 100 mg/kg/d) was orally administered to ovariectomized rats for 3 months. Ovariectomy significantly decreased the estradiol concentration in the serum as compared with that from sham-operated rats. This decrease was not altered by the dose of AHZ. The bone ash weight and mineral density in the femur of ovariectomized rats significantly decreased in comparison with those from sham-operated rats. Moreover, the trabecular bone at the femoral metaphysis was clearly decreased by ovariectomy. The decreases in the femoral ash content and mineral density and the metaphyseal trabecular bone were clearly prevented by the tested doses of AHZ (10, 30 and 100 mg/kg/d). The present finding with histomorphological study further supports the view that the administration of AHZ can prevent bone loss by ovariectomy.

Comparison of the effect of beta-alanyl-L-histidinato zinc and its zinc-chelating ligand on bone metabolism in tissue culture

The present investigation was undertaken to compare the effects of beta-alanyl-L-histidinato zinc (AHZ) and its zinc-chelating ligands on bone metabolism in tissue culture. Calvaria were removed from 3-week-old male rats and cultured for up to 72 h in Dulbecco's modified eagle medium containing zinc sulfate, AHZ, di(N-acetyl-beta-alanyl-L-histidinato)zinc (AAHZ), and di(histidino)zinc (HZ). The bone calcium content and alkaline phosphatase activity were significantly increased in the presence of AHZ or AAHZ (10(-8)-10(-5) M). Those increases were seen at 10(-7) to 10(-5) M zinc sulfate and HZ. The bone deoxyribonucleic acid (DNA) content was significantly increased by AHZ or AAHZ with 10(-7) to 10(-5) M, while 10(-7) M zinc sulfate and HZ had no effect. Thus, AHZ and AAHZ had more potent effect than that of zinc sulfate and HZ. The effect of AHZ, AAHZ and HZ (10(-5) M) increasing bone alkaline phosphatase activity was abolished by the presence of 10(-4) M dipicolinate, a chelator of zinc. Moreover, the effect of these zinc compounds on bone metabolic indices was not seen in the presence of 10(-6) M cycloheximide. The present results suggest that the effect of AHZ and AAHZ on bone metabolism is more potent than that of zinc sulfate and HZ.

[Preretinal vitreous liquefaction following fundus photocoagulation in young rabbits]

We examined the vitreous change after the retina was destroyed by photocoagulation. Multiple photocoagulation with continuous-wave xenon or diode laser was used to create coagulated spots with 5 disc diameters near the optic disc in 26 eyes of 13 pigmented rabbits aged four weeks. After clinical observation, the eyes were enucleated at 2 weeks and 3, 4, and 14 months after photocoagulation. The vitreous was stained with fluorescein and examined by slitlamp while immersed in water. The vitreous remained unchanged in 2 eyes at 2 weeks after photocoagulation. A liquefied lacuna of the vitreous had formed anterior to the retinal scar in 20 eyes (83%) at 3, 4, and 14 months after photocoagulation. The liquefied lacuna assumed a columnar shape with its bottom corresponding to the retinal scar in 2 eyes at 14 months after photocoagulation. These results show that localized liquefaction in the posterior vitreous can be induced by fundus photocoagulation. It appeared that the presence of a normal retina is one of the prerequisites of integrity of the vitreous in young rabbit eyes.

Effect of zinc-chelating dipeptides on osteoblastic MC3T3-E1 cells: activation of aminoacyl-tRNA synthetase

The effect of zinc-chelating dipeptides on osteoblastic MC3T3-E1 cells was investigated. As zinc compounds, we used zinc sulfate, AHZ, di(N-acetyl-beta-alanyl-L-histidinato)zinc (AAHZ), and di(histidino)zinc (HZ). Cells were cultured for 72 h in the presence of zinc compounds (10(-8)-10(-5) M). The effect of AHZ (10(-7) and 10(-6) M) to increase protein and deoxyribonucleic acid (DNA) contents in the cells was the greatest in comparison with those of other zinc compounds. Zinc sulfate and HZ at 10(-7) M did not have an effect on the cellular protein content. AHZ (10(-6) M) had a potent effect on cell proliferation, although zinc sulfate (10(-6) M) had no effect. beta-Alanyl-L-histidine (10(-6) and 10(-5) M) did not have an appreciable effect on the cells. Those effects of AHZ (10(-6) M) on osteoblastic cells were completely abolished by the presence of cycloheximide (10(-6) M). AHZ (10(-8)-10(-5) M) directly activated [3H]leucyl-tRNA synthetase in the cell homogenate, whereas the effect of zinc sulfate was seen at 10(-6) and 10(-5) M. The present study suggests that the chemical form of zinc-chelating beta-alanyl-L-histidine (AHZ) can reveal a potent anabolic effect on osteoblastic cells, and that AHZ directly stimulates protein synthesis.

Effect of zinc-chelating dipeptide on bone metabolism in weanling rats: comparison with beta-alanyl-L-histidinato zinc-related compounds

Rats were orally administered zinc sulfate, di(histidino)-zinc (HZ), beta-alanyl-L-histidinato zinc (AHZ), and di(N-acetyl-L-alanyl-L-histidinato)-zinc (AAHZ) with the doses of 2.75 and 5.50 mg Zn/kg/day for 7 days, and 24 h later they were killed. With the dose of 2.75 mg Zn/kg/day, the administration of AHZ caused a significant increase of zinc content in the femoral diaphysis and a corresponding elevation of alkaline phosphatase activity, deoxyribonucleic acid (DNA), and calcium contents, but similar doses of zinc sulfate, HZ, and AAHZ did not have an appreciable effect on the enzyme activity and DNA content. Moreover, the dose of 5.50 mg Zn/kg/day with AHZ and AAHZ caused an appreciable increase in all zinc compounds observed, whereas zinc sulfate did not have the effect on bone DNA content and HZ had no effect on bone alkaline phosphatase activity. Of the various zinc-chelating dipeptides used, AHZ had a characteristic effect on bone metabolism in weanling rats. Thus, AHZ may have a pharmacological role.

Effect of insulin administration on bone formation is impaired in rats with skeletal unloading

The effect of insulin administration on bone formation was investigated in the femoral diaphysis of rats with skeletal unloading. When the femoral-diaphyseal tissues from normal rats were cultured in the presence of insulin (10(-9) and 10(-8) M) for 48 h, the hormone produced a significant increase of alkaline phosphatase activity, collagen, deoxyribonucleic acid (DNA) and calcium contents in the bone tissues, indicating that it has a direct stimulatory effect on bone formation. Moreover, when normal rats received a subcutaneous administration of insulin (5.0 IU/100 g body weight) 5 times at 24-h intervals, the hormone caused a significant increase of alkaline phosphatase activity, DNA and calcium contents in the femoral diaphysis. Those increases were not seen by insulin administration to the skeletal-unloading rats with hindlimb hang for 4 d. The present results indicate that the stimulatory effect of insulin on bone formation is lost by skeletal unloading. The finding further supports the view that insulin impairment plays an important role in the deterioration of bone formation by microgravity.