Subperiosteal implantation of octacalcium phosphate (OCP) stimulates both chondrogenesis and osteogenesis in the tibia, but only osteogenesis in the parietal bone of a rat

BACKGROUND

It is not known whether long bones and calvaria have distinct biological characteristics. Octacalcium phosphate (OCP), which is a precursor phase of the hydroxyapatite, has been reported to stimulate bone formation if implanted in the subperiosteal region of mouse calvaria. The present study was designed to investigate how the long bone and the calvarium respond to OCP implantation and to compare their biological characteristics.

METHODS

The synthetic OCP was implanted into the subperiosteal region of rat tibiae and parietal bones being mixed with bovine type I collagen treated by pepsin (Atelocollagen). The biological response was examined histologically and immunohistochemically for collagen matrix phenotypes of types I and II to identify bone and cartilage formation.

RESULTS

Both chondrogenesis and osteogenesis were initiated in the tibia 1 week after implantation of OCP and most of the cartilage was replaced by bone at week 2. However, the parietal bone did not show osteogenesis responding to OCP implantation until week 3, and no cartilage formation was associated with the osteogenesis.

CONCLUSIONS

The present study demonstrated the distinct characteristics of biological response to OCP implantation between the long bone and the calvarium in terms of whether or not cartilage formation is involved in the stimulated osteogenesis by OCP, and in terms of timing of the stimulated chondrogenesis and/or osteogenesis, i.e., the parietal bone takes more time to respond to OCP implantation than the tibia.

HLA DRB4 0101-restricted immunodominant T cell autoepitope of pyruvate dehydrogenase complex in primary biliary cirrhosis: evidence of molecular mimicry in human autoimmune diseases

We established six T cell clones specific for pyruvate dehydrogenase complex (PDC)-E2 peptides from four different patients with primary biliary cirrhosis using 33 different peptides of 17-20 amino acid residues corresponding to human PDC-E2 as stimulating antigens. The minimal T cell epitopes of these six T cell clones were all mapped to the same region of the PDC-E2 peptide 163-176 (GDLLAEIETDKATI), which corresponds to the inner lipoyl domain of PDC-E2. The HLA restriction molecules for this epitope were all identified as HLA DRB4 0101. The common essential amino acids of this epitope for these T cell clones were E, D, and K at positions 170, 172, and 173, respectively; other crucial amino acids for this epitope differed in each T cell clone. In addition, the alanine-substituted peptides at positions 170 and 173, but not 172, inhibited the proliferation of all T cell clones induced by the original peptide of human PDC-E2 163-176, indicating that amino acid D at position 172 is a critical MHC-binding site for all T cell clones tested. Interestingly, all T cell clones reacted to PDC-E2 peptide 36-49 (GDLIAEVETDKATV), which corresponds to the outer lipoyl domain of human PDC-E2. Furthermore, one T cell clone cross-reacted with exogenous antigens such as Escherichia coli PDC-E2 peptide 31-44/134-147/235-248 (EQSLITVEGDKASM), which has an EXDK sequence. This is a definite demonstration of the presence of molecular mimicry at the T cell clonal level in human autoimmune diseases. It is also considered possible to design peptide-specific immunotherapy based on the findings of T cell autoepitopes in primary biliary cirrhosis.

A new type of human calcitonin receptor isoform generated by alternative splicing

There are three isoforms of calcitonin receptors (CTRs). The first type (type 1) has 479 amino acids in rat and 482 amino acids in porcine. The second type (type 2) has a 39 amino acid insertion in the second extracellular domain. The third type (type 3) has a 16 amino acid insertion in the first intracellular domain. The CTR which has been isolated from a human ovarian carcinoma cell line belongs to type 3. Using RT-PCR with primers whose sequences correspond to the human CTR cDNA, we analyzed the expression of the CTR transcripts in seven human tumor cell lines and surgical specimens. The CTR m-RNA were found in all samples. Transcripts which were 48bp shorter than that of the type 3 human CTR were detected, but not transcripts of type 2 and type 3. Since the structure of this CTR is same as that of the type 1 rat and porcine CTRs, we termed it the human type 1 CTR. PCR studies using human genomic DNA as a template revealed that the 48bp sequence constitutes an exon. These results indicate that the type 1 and the type 3 human CTRs are generated by alternative splicing and a majority of human CTR transcripts is type 1.

The transcriptional regulation of human arachidonate 12-lipoxygenase gene by NF kappa B/Rel

As examined by the luciferase assay, a negative regulatory region including the NF kappa B motif was found in the 5'-flanking region of the 12-lipoxygenase gene in human erythroleukemia cells. The negative control was abolished by a site-specific mutation of the NF kappa B motif. Probes including the NF kappa B region gave positive bands upon a gel-shift assay. The bands were super-shifted by antibodies for NF kappa B p50, NF kappa B p65 and c-Rel, and were lost by a NF kappa B competitor DNA. Furthermore, the NF kappa B sequence was protected in DNase I footprinting. Thus, two kinds of heterodimer (p50 and p65; p50 and c-Rel) seemed to control the over-expression of the human 12-lipoxygenase gene.

Molecular cloning and characterization of a cDNA encoding monoclonal nonspecific suppressor factor

The monoclonal nonspecific suppressor factor (MNSF) is a lymphokine product of a murine T-cell hybridoma that inhibits the generation of lipopolysaccharide-induced immunoglobulin-secreting cells in an antigen-nonspecific manner. A cDNA clone encoding MNSF beta (an isoform of MNSF) was isolated and expressed in bacteria. The sequence obtained is virtually identical to the Fau protein, a product of the ubiquitously expressed fau gene with unknown function. Northern blot analysis demonstrated a single, 0.6-kb transcript. Specific polyclonal antibodies against synthetic peptides corresponding to the deduced amino acid sequences were elicited in rabbits. Immunoprecipitation experiments with these antibodies showed that MNSF beta is released extracellularly in an aggregate form, albeit it lacks a signal peptide sequence. The anti-MNSF beta affinity eluate from the MNSF-producing murine hybridoma (E17) and concanavalin A-activated splenocyte culture supernatants inhibited the immunoglobulin production by lipopolysaccharide-activated splenocytes. Recombinant MNSF beta also showed a similar biologic activity. Thus, ubiquitin-like protein(s) may be involved in the regulation of the immune responses.

Human peripheral eosinophils have a specific mechanism to express gp91-phox, the large subunit of cytochrome b558

Eosinophils as well as neutrophils, monocytes and B lymphocytes are noted for lacking normal cytochrome b558 in patients with X-linked chronic granulomatous disease. The eosinophils of an X-linked male patient, however, fully expressed surface cytochrome b558, generated superoxide anion to a normal extent and definitely expressed the large subunit of cytochrome b558 (gp91-phox). His mononuclear leukocytes contained a diminished amount of gp91-phox mRNA with normal coding sequences. All the coding sequences and a putative poly (A) signal of his gp91-phox gene were normal. These results indicate that eosinophils have a specific mechanism to express gp91-phox and suggest that the mechanism lies at the transcriptional step of the gene.

Effect of angiotensin II receptor blocker on angiotensin II stimulated DNA synthesis of cultured human aortic smooth muscle cells

To examine the role of the renin-angiotensin system on human vascular smooth muscle cell (VSMC) replication, we studied the effect of DUP 753, an angiotensin II (ANG II) type 1 receptor antagonist, on ANG II stimulated tritiated-thymidine (3H-Tdr) incorporation into cultured human aortic VSMC. ANG II stimulated DNA synthesis of VSMC in a dose-dependent manner as estimated by 3H-Tdr incorporation (control; 2993 +/- 486 cpm, 10(-8)M; 3360 +/- 350 cpm, 10(-7)M; 3474 +/- 516 cpm, 10(-6)M; 4889 +/- 320 cpm, P < 0.01). The effects of ANG II were clearly inhibited by 10(-7) M DUP 753 (ANG II 10(-8) M; 3360 +/- 350 vs 509 +/- 39 cpm, 10(-7) M; 3474 +/- 516 vs 661 +/- 36 cpm, 10(-6) M; 4889 +/- 320 vs 806 +/- 76 cpm, each P < 0.01). This receptor antagonist decreased the basal 3H-Tdr incorporation of VSMC from 2933 +/- 486 to 411 +/- 78 cpm (P < 0.01). Furthermore, DUP 753 decreased 10(-7) M ANG II-stimulated 3H-Tdr incorporation of VSMC in a dose-dependent manner (control; 2627 +/- 256 cpm, 10(-9) M; 2145 +/- 143 cpm, 10(-8) M; 1047 +/- 543 cpm, 10(-7) M; 639 +/- 169 cpm, 10(-6) M; 642 +/- 59 cpm, P < 0.01). These observations suggest that, in human VSMC, ANG II type 1 receptors are important for the regulation of both stimulated and basal cell proliferation. It may therefore be worth while to examine the clinical usefulness of DUP 753 for preventing abnormal VSMC growth.

Mechanism of chromium(VI) toxicity in Escherichia coli: is hydrogen peroxide essential in Cr(VI) toxicity?

To investigate the role of hydrogen peroxide in Cr(VI) toxicity in vivo toward bacterial cells, we examined the effect of Cr(VI), hydrogen peroxide, sodium azide, and mannitol on the viability of Escherichia coli. Bacterial cells were incubated for 1 h with shaking in the presence of Cr(VI), hydrogen peroxide, sodium azide as catalase inhibitor, and/or mannitol as radical scavenger. The colony-forming ability and double-strand DNA degradation were examined. The viability assays revealed that Cr(VI) toxicity depended on hydroxyl radicals generated in the reaction involving hydrogen peroxide and chromium. Moreover, incubation of E. coli cells with 10 mM Cr(VI) and 3 mM hydrogen peroxide caused the degradation of double-strand DNA in vivo, which was suppressed by the addition of mannitol. These results indicated that hydroxyl radicals generated in the incubation degraded DNA of E. coli cells, resulting in cell death. In the absence of added hydrogen peroxide, the intracellular concentration of hydrogen peroxide in E. coli was low (below 1 microM). A catalase-defective strain incubated in the absence of added hydrogen peroxide remained fully viable after 1 h but showed decreased viability after prolonged incubation (4-8 h). The addition of mannitol suppressed this decrease, suggesting that hydroxyl radicals may be involved in the expression of Cr(VI) toxicity even without added hydrogen peroxide.

Screening for QT prolongation using a new exponential formula

We prospectively screened 14,227 school-aged children for evidence of QT prolongation using a exponential formula (eQTc = (QT interval)/(RR interval)0.31) and criteria (ie: abnormal eQTc was defined as being equal to or greater than 0.430 and 0.435 for male and female first-graders, respectively, and 0.440 and 0.445 for male and female seventh-graders, respectively). We previously reported that this new exponential correction of the QT interval may be useful for eliminating the effect of heart rate in school-aged children. Computer analyses detected 13 children with abnormally prolonged eQTc. All of the children who had abnormal QTc values by conventional QTc criteria also had abnormal eQTc values using the new criteria. Nine of these 13 children were ultimately confirmed to have a prolonged QT interval. Six cases of QT prolongation were detected that would not have been found if conventional screening criteria were used, since these cases had heart rates greater than 75 beats/min. One child had parents who were deaf. This case would not have been detected if only conventional screening were used. These results suggest that exponential correction of the QT interval (eQTc) is useful for prospectively screening large populations for evidence of QT prolongation.

Characterization of the superoxide-generating system in human peripheral lymphocytes and lymphoid cell lines

In B lymphocytes, but not T lymphocytes, isolated from human peripheral blood, we detected the four protein components essential for "the respiratory burst" by immunoblot analyses using peptide-directed antibodies. These are two membrane proteins, namely, 91- and 22-kDa subunits of cytochrome b558, and two cytosolic proteins with molecular masses of 47 and 65 kDa. Like in neutrophils, cytochrome b558 was expressed on the cell surface of peripheral B lymphocytes. Mean amounts (n = 8) of the 91-, 22-, 47-, and 65-kDa proteins, respectively, in peripheral B lymphocytes calculated from intensity of the blots were 0.011 +/- 0.003, 0.026 +/- 0.006, 0.179 +/- 0.022, and 0.039 +/- 0.013 relative to those in neutrophils on the basis of cell number. Epstein-Barr virus (EBV)-transformed cell lines derived from normal B lymphocytes and some B cell lines also possessed cytochrome b558 and two cytosolic proteins. Isolated human peripheral B lymphocytes generated the superoxide anion upon cross-linking of surface antigens such as IgM, IgD, IgG, HLA-DR, and CD19. EBV-transformants derived from normal peripheral B lymphocytes and B lymphoid cell lines also generated the superoxide anion when stimulated with various antibodies against surface antigens. These results indicate that peripheral B lymphocytes have substantial amounts of a superoxide-generating system identical to that in phagocytes and that the system is stimulated to generate the superoxide anion by the cross-linking of clonally expressed surface immunoglobulins or of certain surface antigens.

Prolonged but not acute fluoxetine administration produces its inhibitory effect on hippocampal seizures in rats

This study assessed the effects of acute as well as long-term administration of fluoxetine, a selective serotonin (5-HT) reuptake inhibitor with anti-depressant properties, on hippocampal (HIP) seizures elicited by electrical stimulation in rats. The fluoxetine effect on HIP seizures was also assessed following long-term treatment with gepirone, a 5-HT1A receptor agonist. Acute single administration of fluoxetine (1, 10 mg/kg; IP) was found to produce no significant effect on HIP seizure activity. Following daily IP administration of fluoxetine (10 mg/kg per day) or gepirone (10 mg/kg per day) for 21 days, animals were given a 7-day drug-free period and then challenged with an acute dose of 10 mg/kg fluoxetine. These treatment regimens resulted in a significantly increased afterdischarge threshold of HIP seizures in response to acute fluoxetine administration. The inhibitory effect of fluoxetine, however, was not present 4 weeks after long-term treatment with either fluoxetine or gepirone. The present results indicate that long-term treatment with these compounds enhances the antiepileptic effect of subsequent fluoxetine administration on the generation of HIP seizures. This effect is possibly related to the well-demonstrated evidence that fluoxetine and gepirone, on long-term treatment, facilitate net 5-HT neurotransmission through desensitization of presynaptic 5-HT autoreceptors.

Determination of magnesium ion by use of the coupled-enzyme method with pyruvate kinase and lactate dehydrogenase

We developed a new convenient method for determination of magnesium ion concentrations by use of magnesium ion-dependent enzymes; pyruvate kinase and lactate dehydrogenase. This method is based on the determination of the reaction rate of pyruvate kinase which uses MgADP- as substrate. The reaction rate of pyruvate kinase is dependent upon the formation of the complex with ADP and magnesium ion and the amount of the complex is dependent upon that of magnesium ion. The reaction rate of pyruvate kinase can be easily and spectrophotometrically determined by using lactate dehydrogenase and NADH as the decreased amount of absorbance at 340 nm.

Cloning of the Rhizopus niveus pyr4 gene and its use for the transformation of Rhizopus delemar

We have cloned a pyr4 gene encoding orotidine-5'-monophosphate decarboxylase of the filamentous fungus Rhizopus niveus. The pyr4 gene of R. nivens has an open reading frame composed of 265 amino-acid residues and has two putative introns. We have also isolated a pyr4 mutant of Rhizopus delemar from 5-fluoroorotic acid-resistant mutants and transformed it with the pyr4 gene of R. niveus as a selectable marker. Introduced DNA was integrated into the chromosome in a multiple tandem array. The mitotic stability of the introduced DNA was increased by a repeated sporulation process. The expression of the Escherichia coli beta-glucuronidase gene in R. delemar was successfully obtained under the control of the pgk2 gene promoter of R. niveus by co-transformation with the pyr4 gene.

Morphological studies on the kidney of the spontaneous nephrotic (ICGN) mice in the late stage

Spontaneous nephrotic (ICGN) mice develop proteinuria, hypoproteinemia and hypercholesterolemia. These symptoms steadily progress to chronic renal failure. Details of the changes of the kidney, in the late stage (more than 5 months old) were investigated by both light and electron microscopy. The kidney exhibited a slightly whitish, granular surface and the cortex became thinner and contained fibrous lesions, in which clusters of unaffected and occluded renal tubules were randomly scattered. In the juxtamedullary and outer medullary zone, there were highly dilated renal tubules, which sometimes contained urinary casts. The glomerulus exhibited basement membrane thickening in the capillary loops and the capillary lumen was narrowed in size and sometimes occluded. No detachment of the podocyte from the basement membrane was observed and the podocyte foot-processes were extensively fused, causing their characteristic slits to be lost. The thickened basement membranes were found both in the glomerulus and around the occluded renal tubules, while the basement membrane in the dilated renal tubule appeared normal. Therefore, the basement membranes of the glomerulus and renal tubules appear to react differently in the pathogenesis of the condition. In conclusion, ICGN mice are a good model for not only the nephrotic syndrome but also for chronic renal failure.

[A case of hemophagocytic syndrome manifesting adult Still's disease and acute hepatitis]

We report a 20 year-old woman with hemophagocytic syndrome. In February 1993, she developed high fever, arthralgia, salmon-like pink eruption, leukocytosis and splenomegaly. She was diagnosed as adult Still's disease and successfully treated with intravenous immunoglobulin and oral prednisolone. In September 1993, she was re-admitted to our hospital complaining of general fatigue and low grade fever and treated with oral prednisolone at a daily dose of 15 mg. On October 2, 1993, she suddenly developed high fever and salmon-like pink eruption on her leg followed by the marked increase of serum transaminase and LDH levels (GOT 3,270 IU/l, GPT 1,880 IU/l, LDH 5,480 IU/l) on October 7. Since hepatic failure progressed, we started methylprednisolone pulse therapy and plasmapheresis. However, because of the progression of pancytopenia caused by hemophagocytosis, the treatment with VP-16 was initiated. However, she died of DIC on November 2, 1993. Autopsy revealed submassive necrosis of the hepatocytes with moderate infiltration of histiocytes. She was retrospectively diagnosed as hemophagocytic syndrome whose manifestations are very similar to those in adult Still's disease and acute viral hepatitis.

Correction of the QT interval in children

We evaluated the usefulness of 11 formulas for correcting the QT interval in children, including the square root, cubic root, logarithmic, linear, exponential, and inverse formulas using the Mean-squared residual (MSR) values and Akaike Information Criterion (AIC) in 8,086 first-graders, 9,989 seventh-graders, and 5,786 tenth-graders. The subjects were divided into six groups according to age and sex. MSR and AIC values were lowest in all of the groups for the exponential formula (eQTc) and Fridericia's formula (fQTc). We then evaluated the relative usefulness of these two formulas by determining the optimal value for parameter k using the following exponential model: eQTc = (QT interval)/(RR interval)k. The best-fit value for k was different for each group. However, the tentative abnormal eQTc and fQTc values, determined by statistical analysis, were equivalent in all groups when 0.31 was used as the exponential parameter k. These results suggest that the exponential formula and Fridericia's formula are equally useful for screening for QT prolongation.

Regulation of follistatin messenger ribonucleic acid in cultured rat granulosa cells

The regulation of the follistatin mRNA by hormones and endocrine manipulations was examined in granulosa cell cultures. The follistatin mRNA accumulation was stimulated in a dose-dependent manner by follicle-stimulating hormone (FSH) with a maximal response twice as great as in control cultures at a dose of 100 ng/ml FSH. The time course of the FSH effect on follistatin mRNA had a biphasic effect in which FSH increased follistatin mRNA within 2 h, and subsequently reduced it to below the control level. 8-Br-8 brom-adenosine 3,5-cyclic monophosphate (cAMP) (2 mM) and phorbol 12-myristate 13-acetate (PMA) (10 nm) induced a time-dependent increase in follistatin mRNA levels, with the maximal response at 6 h and 2 h, respectively. Co-treatment of the granulosa cells with cAMP and PMA demonstrated that 0.2 mM of 8-Br-cAMP suppressed the follistatin mRNA of the control and the samples with a small amount of PMA in the granulosa cells. Follistatin expression is therefore regulated by protein kinase A and protein kinase C pathways in rat granulosa cells. A more dramatic stimulation of follistatin mRNA was observed when this culture was treated with activin, and follistatin also blocked the effect of activin on the follistatin mRNA.

Functional analysis of the human interleukin 2 receptor gamma chain gene promoter

The third component of the interleukin (IL) 2 receptor, gamma chain, is essential not only for IL-2- but also for IL-4-, IL-7-, IL-9-, and IL-15-induced proliferation of lymphocytes. To elucidate the mechanisms by which the gamma chain is expressed, we have analyzed the promoter region of the gamma chain gene. The 633-base pair fragment upstream of the initiation codon showed the promoter activity in human hematopoietic cell lines, Jurkat and THP-1, when linked to the luciferase gene. With a series of 5'-deletion mutants, the basal promoter activity was found in a fragment from nucleotide 80 to 58 upstream from the RNA start site, including an Ets binding sequence. Treatment of cells with either 12-O-tetradecanoylphorbol-13-acetate or phytohemagglutinin but not forskolin induced transcription from the gamma chain gene promoter. A viral trans-acting transcriptional activator, Tax, of human T-cell leukemia virus type I elevated expression of the gamma chain gene. In contrast, IL-2 decreased transcription from the IL-2 receptor gamma chain promoter. These results suggest that expression of the gamma chain is regulated at the transcription level by extracellular stimuli and may be implicated in immune response.

Quantitation of IL-1 beta mRNA by a combined method of RT-PCR and an ELISA based on ion-sensitive field effect transistor

A method for quantitative RT-PCR using ELISA detection was developed and applied to the quantitation of IL-1 beta mRNA in clinical samples. To compensate for the 'tube effect' of RT-PCR, a synthetic RNA, pRSET RNA, was added to sample solutions as an internal standard and co-amplified with IL-1 beta mRNA. Sense primers for IL-1 beta and pRSET were labeled with digoxigenin and FITC, respectively, while anti-sense primers for both were labeled with biotin. Double-stranded PCR products were captured by two solid-phase pipettetips. One was coated with an anti-digoxigenin antibody and another with an anti-FITC antibody, and sandwiched by avidin-urease, and their activities were measured by coupling them with a pH-FET in a pH-measuring cell containing urea solution. The ratio of the signal intensity for IL-1 beta to that for pRSET was used to quantify the concentration of IL-1 beta mRNA. A calibration curve was obtained by using a known amount of AW 109 RNA as an external standard of IL-1 beta RNA. It was found that 10(2)-10(6) copies of IL-1 beta mRNA were measurable by the present method. Expression levels of IL-1 beta mRNA in clinical samples, such as monocytes of peripheral blood or synovial cells from patients with RA or OA, were determined.

The role of cyclic AMP in the lipopolysaccharide-induced suppression of thymidine kinase activity in macrophage

We observed that lipopolysaccharide (LPS, 1 micrograms/ml) can suppress [3H]thymidine incorporation into acid-insoluble fraction in a mouse macrophage cell line J774 (over 70% at 6 h) without affecting the uptake of [3H]thymidine or DNA polymerase activity. Paralleling this suppression, a decrease in the thymidine kinase (TK) activity, but not of thymidine monophosphate (TMP) kinase and thymidine diphosphate (TDP) kinase, was observed. LPS dose-dependently increased intracellular cAMP levels to about 3.5-times basal at 6 h, proportionally to the decrease of the TK activity. Elevation of intracellular cAMP by several reagents also decreased TK activity. Apparently LPS treatment elevates cAMP concentration by decreasing the low Km cAMP phosphodiesterase activity (58% at 6 h). The time course of cAMP-dependent protein kinase (PK-A) activity during the first 6 h after LPS treatment correlated with that of cAMP concentration. Treatment with a PK-A inhibitor restored about 63% of LPS-induced reduction of TK activity at 6 h. At longer times, however, there was a discrepancy between the change of cAMP concentration or PK-A activity and the reduction of TK activity. Therefore, protein kinase activation caused by the accumulation of intracellular cAMP probably triggers some mechanism responsible for the reduction of the TK activity.

Myosin-actin interaction plays an important role in human immunodeficiency virus type 1 release from host cells

We examined the potential role of myosin and actin in the release of human immunodeficiency virus type 1 (HIV-1) from infected cells. Wortmannin (100 nM to 5 microM), an effective inhibitor of myosin light chain kinase, blocked the release of HIV-1 from infected T-lymphoblastoid and monocytoid cells in a concentration-dependent manner. Cytochalasin D, a reagent that disrupts the equilibrium between monomeric and polymeric actin, also partially inhibited the release of HIV-1 from the infected cells. At the budding stage, myosin and HIV-1 protein were detected in the same areas on the plasma membrane by using dual-label immunofluorescence microscopy and immunoelectron microscopy. In the presence of 5 microM wortmannin, viral components were observed on the plasma membrane by using immunofluorescence microscopy and electron microscopy, implying that wortmannin did not disturb the transport of viral proteins to the plasma membrane but rather inhibited budding.

[Stereotactic radiosurgery using a linear accelerator (LINAC): simulation and positioning]

Stereotactic radiosurgery using a Gamma unit obtains good results for small intracranial diseases, arteriovenous malformation (AVM) and acoustic neurinoma. In stereotactic radiosurgery using a linear accelerator (LINAC), many fundamental problems are to be solved. 1) accuracy of a LINAC, 2) making the collimators for high energy X-ray narrow beams, 3) dosimetry for high energy X-ray narrow beams, 4) irradiation methods for stereotactic radiosurgery, 5) fixation of a patient's head and 6) simulation of a target. The usefulness of our method for simulation of a target and for positioning for radiosurgery was investigated. High energy X-ray narrow beams obtained with the collimators for narrow beams (field sizes: 9mm phi, 18mm phi and 27mm phi) satisfy clinical requirements for stereotactic radiosurgery, as indicated by dose profiles and isodose curves. No dosimetry method for high energy X-ray narrow beams has been established yet. Of the main irradiation methods for stereotactic radiosurgery, the method using multiple non-coplanar converging arcs needs no drastic reconstruction for use with LINAC. A patient's head was completely fixed by the stereotactic frame (Patil stereotaxic system or Leksell micro-stereotactic system). Simulation of a target was performed under CT scan. On CT image, the center of a target was determined and the three-dimensional coodinate on the stereotactic head frame target was settled so that the target would be reached. The three-dimensional coordinate for the target was coincided with the isocenter of a LINA by the laser beams of three-directional pointers. Afterwards, the target position was finely adjusted, by using the target positioner manipulator system.(ABSTRACT TRUNCATED AT 250 WORDS)

Hypothalamic hamartoma: anatomic, immunohistochemical and ultrastructural features

Four patients with hypothalamic hamartoma were examined by CT and/or MR imaging, immunohistochemistry and electron microscopy. The hamartomas arose from the hypothalamus and extended inferiorly. LH-RH neurons were detected in three cases by immunohistochemistry. Electron microscopy revealed large myelinated axons, axon terminals containing dense-core vesicles and axon terminals with clear vesicles forming asymmetrical synapses. The development of hypothalamic hamartoma and its functional manifestations (precocious puberty and laugh attacks) are discussed in reference to the migration of LH-RH neurons from the olfactory placode.

Follow-up of 2,733 Japanese patients with myocardial infarction

Two thousand, seven hundred and thirty-three patients with acute myocardial infarction (AMI) who were admitted to our 11 institutions between 1983 and 1988, examined by coronary arteriography and discharged alive, were followed for an average of 2.9 years. During the follow-up period, 212 patients (7.6%) died. The factors that governed the prognosis of myocardial infarction after discharge were advanced age, female gender, obesity, previous infarction, angina pectoris more than 1 month before the onset of AMI, post-infarction angina, multiple-vessel diseases, advanced stage by Killip's and/or Forrester's classification on admission, elevated pulmonary capillary arterial pressure, decreased cardiac index, decreased left ventricular ejection fraction, increased left ventricular end-diastolic volume and left ventricular aneurysm before hospital discharge. Patients with ventricular tachycardia or ventricular fibrillation during hospitalization showed a poor prognosis. In contrast, patients who received intracoronary thrombolysis, or emergent and/or elective percutaneous transluminal coronary angioplasty showed a favorable prognosis.

Effects of lateral pterygoid muscle hyperactivity on differentiation of mandibular condyles in rats

BACKGROUND

The effects of biomechanical stress on the growth and development of the mandibular condyle have been studied by many investigators. However, the role of the lateral pterygoid muscle in this development is not clear.

METHODS

Hyperfunction of the lateral pterygoid muscles of male 3-week-old Sprague-Dawley rats was induced by electrical stimulation, and the responses of the mandibular condyles were compared to control tissues by a double-fluorescent staining technique using polyclonal antibodies against type I and type II collagen. Electrical stimulation consisted of repeated application (5 seconds on/5 seconds off) of a 5 Hz current for up to 7 days.

RESULTS

In the first 2 days, cartilaginous tissues rich in type II collagen disappeared in the anterior and posterior areas, which were loaded by tensional force due to direct and indirect attachment of the lateral pterygoid muscles. Tissues in these areas were replaced by intramembranous bone that was reactive for type I collagen at 7 days. By the end of the experiment, the trabecula of the condyle was remodeled more perpendicularly, thus resisting the compressive force due to hyperfunction of the lateral pterygoid muscles.

CONCLUSIONS

These results suggest that the activity of the lateral pterygoid muscle might play a significant role in the differentiation of progenitor cells and in the maturation and calcification of chondrocytes in mandibular condyles.