Retro-dental reactive lesions related to development of myelopathy in patients with atlantoaxial instability secondary to Os odontoideum

STUDY DESIGN

A retrospective analysis of 13 patients with atlantoaxial instability secondary to Os odontoideum who underwent posterior atlantoaxial fusion.

OBJECTIVE

To assess the relationships between the development of myelopathy and plain radiographic parameters in patients with atlantoaxial instability secondary to Os odontoideum and to determine whether the pathologic structures, which compress the spinal cord, are visualized using magnetic resonance imaging.

SUMMARY OF BACKGROUND DATA

The development of myelopathy, which is the most serious complication associated with Os odontoideum, was thought to be related to either the degree of instability or direction of instability, or a decrease in the space available for the cord. However, such indirect radiographic parameters measured using plain radiographs cannot provide direct information concerning the causes of myelopathy in patients with atlantoaxial instability secondary to Os odontoideum.

METHODS

Thirteen patients who underwent posterior atlantoaxial fusion for clinical symptoms due to Os odontoideum were classified into two groups depending on whether they had (n = 9) or did not have (n = 4) myelopathy. Four radiographic parameters were measured using flexion and extension lateral radiographs; the degree of instability, the direction of instability, and the space available for the cord in flexion and extension. MRI was performed on all patients in the myelopathy group. The radiologic and clinical data were compared for the two groups.

RESULTS

There were no significant statistical differences in the degree of instability (6.83 vs. 7.38, P = 0.816), space available for the cord in flexion (6.94 vs. 7.13, P = 0.938), and space available for cord in extension (7.56 vs. 5.75, P = 0.434) between the two groups. There was a poor agreement between the direction of instability and the development of myelopathy (kappa = 0.268, P = 0.308). Magnetic resonance imaging did demonstrate, however, cord compression caused by retro-dental reactive lesions in the myelopathy; cystic masses were present in two patients; and fibrocartilaginous masses were present in seven.

CONCLUSION

The current study suggests that the value of plain radiographic parameters should be reevaluated as a means of evaluating myelopathy in patients with atlantoaxial instability secondary to Os odontoideum, and that retro-dental reactive lesions should be considered as the potential cause of myelopathy.

Molecular cloning and sequencing of rat Cdc42 GTPase cDNA

Cdc42 is a member of the Rho family of small GTP-ase and plays an important role in intracellular signaling pathways regulating cell morphology, motility and stimulation of DNA synthesis. We have isolated cDNA encoding Cdc42 from a rat brain cDNA library using PCR-cloning strategy. The sequence of isolated gene revealed an open reading frame of 576 nucleotides with the potential to encode a protein of 191 amino acids with a predicted molecular weight of 21 kD. The resulting sequence was incorporated into the GenBank with accession number, AF205635. Sequence analysis revealed that overall cDNA sequence identity is 96% with human G25K and 52% with rat Chp, a homologue of the GTPase human Cdc42Hs, and having one nucleotide difference from the mouse Cdc42. However, putative protein sequence was identical to the mouse and human brain Cdc42Hs. On expression of the cDNA in COS-7 cells, a protein molecular weight of 21 kD was detected in immunoblotting using anti-human Cdc42 antibodies. Therefore, these results suggest that the cDNA we are reporting is most likely the rat homologue of the GTPase human Cdc42.

Differential activation of c-Jun NH2-terminal kinase and p38 mitogen-activated protein kinases by methyl methanesulfonate in the liver and brain of rats: implication for organ-specific carcinogenesis

Methyl methanesulfonate (MMS), a direct-acting alkylating agent, is a strong brain carcinogen but a poor hepatocarcinogen in rats. To elucidate the mechanism(s) leading to tissue-specific carcinogenesis in response to MMS, we compared the activation of the stress-activated protein kinases (SAPKs), the c-Jun NH2-terminal kinase (JNK) and p38, in the liver and brain of rats after i.p. injection of MMS. p38 was activated in both the liver and brain, but JNK was activated only in the liver in a dose- and time-dependent manner. The activation of JNK was preceded by the activation of SAPK or extracellular signal-regulated protein kinase kinase 1/mitogen-activated protein kinase kinase 4 in the liver, but no activation of SAPK or extracellular signal-regulated protein kinase kinase 1/mitogen-activated protein kinase kinase 4 was observed in the brain. The activation of JNK in the liver was accompanied by increased phosphorylation of activating transcription factor 2 and followed by an increase in the phosphorylation and level of c-Jun protein, in contrast to no such changes in the brain. To study the physiological consequences of these differential molecular events in the liver and brain, we examined MMS-induced apoptosis, a process shown to involve stress kinase activation. A significant increase in apoptotic cell death was detected in the liver but not in the brain after a MMS injection, which correlated with the patterns of JNK activation in the liver. Taken together, our results demonstrate that a tissue-specific signaling pathway(s) leading to distinct physiological responses in the liver and brain of rats exposed to MMS exists, suggesting a possible explanation for tissue-specific carcinogenic effects exerted by MMS in vivo.

Effect of Korea red ginseng on the blood pressure in conscious hypertensive rats

The change of blood pressure and heart rate after intravenous injection of Korea red ginseng (KRG) were studied in the conscious normotensive and one-kidney, one-clip Goldblatt hypertensive (1K, 1C-GBH) rats. Crude saponin (CS) of KRG (50, 100 mg/kg i.v.) induced a hypotensive effect and bradycardia in a dose-dependent manner in the anesthetized rats. On the other hand, CS of KRG (100 mg/kg) induced a hypotensive effect and reflex tachycardia in the conscious rats. Saponin-free fraction (SFF) of KRG did not affect them in the anesthetized normotensive rats (P>.05). The maximal hypotensive effect by CS of KRG in the conscious 1K, 1C-GBH hypertensive rats and L-nitroarginine methyl ester (L-NAME, 40 mg/kg)-treated conscious hypertensive rats was not different from that of conscious normotensive rats (Delta 31.6+/-6.3, Delta 27.5+/-5.8 vs. Delta 26.7+/-4.3 mmHg, P>.05). However, pretreatment of L-NAME significantly inhibited the reflex tachycardia by CS of KRG (70.8+/-7.0 vs. 30.6+/-15.0 bpm, P<.05). Hemolysate-sensitive nitric oxide (NO) current by the CS of KRG was greater than that of the SFF of KRG (651.9+/-128.2 pA for CS and 164.9+/-92.5 pA for SFF, P<.001). These findings suggest that KRG has a hypotensive effect and its effect may be due to saponin fraction of KRG in the conscious rats. The releasing effect of NO of KRG, like NO donor, may be partly contributed to the hypotensive effect of KRG.

Localization of the cyclic ADP-ribose-dependent calcium signaling pathway in hepatocyte nucleus

CD38 is a type II transmembrane glycoprotein found on both hematopoietic and non-hematopoietic cells. It is known for its involvement in the metabolism of cyclic ADP-ribose (cADPR) and nicotinic acid adenine dinucleotide phosphate, two nucleotides with calcium mobilizing activity independent of inositol trisphosphate. It is generally believed that CD38 is an integral protein with ectoenzymatic activities found mainly on the plasma membrane. Here we show that enzymatically active CD38 is present intracellularly on the nuclear envelope of rat hepatocytes. CD38 isolated from rat liver nuclei possessed both ADP-ribosyl cyclase and NADase activity. Immunofluorescence studies on rat liver cryosections and isolated nuclei localized CD38 to the nuclear envelope of hepatocytes. Subcellular localization via immunoelectron microscopy showed that CD38 is located on the inner nuclear envelope. The isolated nuclei sequestered calcium in an ATP-dependent manner. cADPR elicited a rapid calcium release from the loaded nuclei, which was independent of inositol trisphosphate and was inhibited by 8-amino-cADPR, a specific antagonist of cADPR, and ryanodine. However, nicotinic acid adenine dinucleotide phosphate failed to elicit any calcium release from the nuclear calcium stores. The nuclear localization of CD38 shown in this study suggests a novel role of CD38 in intracellular calcium signaling for non-hematopoietic cells.

Cardiac phospholipase D2 localizes to sarcolemmal membranes and is inhibited by alpha-actinin in an ADP-ribosylation factor-reversible manner

Myocardial phospholipase D (PLD) has been implicated in the regulation of Ca(2+) mobilization and contractile performance in the heart. However, the molecular identity of this myocardial PLD and the mechanisms that regulate it are not well understood. Using subcellular fractionation and Western blot analysis, we found that PLD2 is the major myocardial PLD and that it localizes primarily to sarcolemmal membranes. A 100-kDa PLD2-interacting cardiac protein was detected using a protein overlay assay employing purified PLD2 and then identified as alpha-actinin using peptide-mass fingerprinting with matrix-assisted laser desorption/ionization mass spectroscopy. The direct association between PLD2 and alpha-actinin was confirmed using an in vitro binding assay and localized to PLD2's N-terminal 185 amino acids. Purified alpha-actinin potently inhibits PLD2 activity (IC(50) = 80 nm) in an interaction-dependent and ADP-ribosylation factor-reversible manner. Finally, alpha-actinin co-localizes with actin and with PLD2 in the detergent-insoluble fraction from sarcolemmal membranes. These results suggest that PLD2 is reciprocally regulated in sarcolemmal membranes by alpha-actinin and ARF1 and accordingly that a major role for PLD2 in cardiac function may involve reorganization of the actin cytoskeleton.

Presentation and mortality of primary biliary cirrhosis in older patients

OBJECTIVES

many patients with primary biliary cirrhosis present for the first time aged over 65, but it is unclear whether the disease is different in older patients. We have examined presentation and mortality in relation to age at which primary biliary cirrhosis was first suspected clinically.

DESIGN

we identified 1023 patients from our regional primary biliary cirrhosis database with definite or probable primary biliary cirrhosis (689 definite); 397 (39%) presented aged > or =65. Definite primary biliary cirrhosis was defined as a positive antimitochondrial antibody titre > or =1/40, abnormal liver enzymes and compatible/diagnostic histology; probable as the presence of two of these indications.

RESULTS

there was no difference in presenting clinical features between the older and younger groups. Older patients were significantly less likely than younger to have had liver biopsy (50% vs 78%; P < 0.001). The 1023 patients had been followed for 8561 patient years. Follow-up was shorter (5.9+/-4 vs 9.8+/-5.5 years; P < 0.001) in the older group because of higher cumulative mortality (59% vs 33%; P < 0.001). Liver-related deaths were significantly commoner in the older group (18% vs 13%; P < 0.05). The mortality ratio for liver deaths (liver deaths per year of follow-up) was 2.4 times higher in the older group (0.031 vs 0.013).

CONCLUSIONS

patients with primary biliary cirrhosis who are over and under 65 have similar features on presentation. The annual risk of liver death is 2.4 times higher in those presenting over 65, reaffirming the importance of age as an independent prognostic factor in an unselected primary biliary cirrhosis population.

Mutation and expression of the p27KIP1 and p57KIP2 genes in human gastric cancer

Cyclin-dependent kinase inhibitors (CDKI) are negative regulators of cell cycle progression by binding the cyclin-CDK complex and inhibiting the CDK activity. Genetic alteration in the CDKI genes has been implicated for carcinogenesis. To test the genetic alteration in the p27 and p57 genes, KIP family CDKI genes, 30 gastric tumor-normal pairs and 8 gastric cancer cell lines were analyzed for mutations by polymerase chain reaction-single strand conformational polymorphism (PCR-SSCP). No mutation was detected in these genes although length polymorphisms in the proline-alanine repeat of the p57 gene were detected. When the p27 and p57 mRNAs were analyzed in gastric cancer cell lines by RT-PCR, the p27 mRNA was expressed considerably high in tumor cells but expression of the p57 mRNA was much low in gastric cancer cell lines compared to that of normal cells. The result suggests that inactivation of gene expression rather than mutations in the p57 gene accounts possibly for the involvement of this gene in tumorigenesis of gastric cancer. However, expression of the p27 gene seems to be essential for cell survival.

Precoating of ultrahigh molecular weight polyethylene with polymethylmethacrylate: interfacial strength

Fixation of polymeric implants, especially an ultrahigh molecular weight polyethylene (UHMWPE) acetabular cup, to a host bone site has been a challenge since its first conception from the Charnley low friction total hip arthroplasty. Destabilization of the acetabular cup, similar to the well-documented cases of femoral stems, is caused mainly by aseptic loosening; the mobile loosened particles further contribute to the progression of aseptic loosening. Although the obvious fixation problems lie in the bone-bone cement interface, little work has been done to reduce the loosening by improving the acetabular components as a whole in cemented procedures. Most of the grooved outer surface, external fixation devices, and metal backings have been introduced to avoid problematic fixation of the cup to bone cement; nevertheless, the designs themselves to some degree became the source of the loosening problems. One possible way to improve the adhesion of acrylic bone cement to the UHMWPE acetabular cup is precoating the surface with polymethylmethacrylate (PMMA). This study successfully precoated the UHMWPE surface with PMMA, showing good chemical and mechanical stability, and suggests the optimal conditions of variables involved in the newly developed precoating process. The highest interfacial tensile strength was 11.51 +/- 0.65 MPa, which is stronger than those of UHMWPE and metal in metal-backed cups (6.3 MPa) and bone-bone cement (8.5 MPa). Further chemical analysis and mechanical testing are in progress, yet the present result of the mechanical tensile strength test showed that the precoating process for the UHMWPE surface could be a viable means toward stable fixation of the polymeric implants by using PMMA bone cement.

Materials and design of spinal implants--a review

Man-made devices have been implanted into the body to relieve pain, to restore function, and to facilitate healing. The subjects of this review are the materials, and to a lesser extent, the design aspects of the numerous implants that are available to the surgeon in dealing with the ailing spine. Often it is the material aspects of such devices that are responsible for their success or failure. It may be that osteoconductive properties are desired for implants to assist fusion, whereas as inert a material as possible would be preferred for interpositional barriers. The materials composing the instrumentation used to facilitate healing of spinal fractures would ideally have properties that optimize strength and biocompatibility, while at the same time minimizing imaging artifacts and allowing a gradual transfer of load from the instrumentation to the vertebral body (i.e., viscoelastic effects). The application of biomaterials and biomechanics to the design of spinal devices is obvious; what may be more subtle though is what the in vivo interactions of these will be. The study of such aspects must continue in order to better evolve the designs and subsequent results of implanted spinal devices.

Interfacial strength between molded UHMWPE and PMMA-MMA monomer treated UHMWPE

To solve aseptic loosening of cemented acetabular cup and tibial plateaus of hips and knee joint prostheses in total joint replacement, adhesion between the polymeric prostheses made of ultra-high molecular weight polyethylene (UHMWPE) and bone cement made of polymethyl-methacrylate (PMMA) has been investigated. Previous studies using xylene, PMMA, and MMA monomer solution to treat bulk surfaces of UHMWPE resulted in 11.5 +/- 0.65 MPa as the maximum interfacial strength between the treated UHMWPE and bone cement. The present study eliminates the use of xylene; instead, UHMWPE powders were treated with MMA monomer and PMMA-MMA solution, dried, and then compression-molded with untreated UHMWPE powders. The interfacial tensile strengths were measured and the best molding conditions investigated by varying temperature, pressure, and time. Temperature was the predominant factor when compared to that of pressure or time. The maximum interfacial strength between the treated UHMWPE and untreated UHMWPE was 16.3 +/- 0.94 MPa with the molding conditions of 166.5 degrees C, 38.7 MPa, and 1 h. Scanning electron microscopic (SEM) pictures show the coating of the nodules and fibrils of UHMWPE powder with PMMA. Pulled out aggregated nodular space and coated PMMA after fracture could be seen easily from PMMA-MMA treated UHMWPE powder.

Effects of antihypertensive therapy on hypertensive vascular disease

Hypertension is associated with alterations in the structure, function, and mechanical properties of large and small arteries. Changes in the endothelium, smooth muscle cell, extracellular matrix, and possibly the adventitia, contribute to complications of hypertension. In large arteries, vascular hypertrophy is found, often with increased stiffness of media components. In small arteries, particularly in mild hypertension, rearrangement of smooth muscle cells around a smaller lumen without changes in media volume (eutrophic remodeling) occurs; in more severe hypertension, hypertrophic remodeling with increased vascular stiffness can be found. Vascular remodeling is accompanied by an increase in the extracellular matrix, particularly collagen deposition. Recent studies have demonstrated that vascular remodeling and endothelial dysfunction of small and large vessels may be normalized by treatment with some antihypertensive agents (angiotensin converting enzyme inhibitors, angiotensin AT(1) receptor antagonists, and long-acting calcium channel blockers). Angiotensin converting enzyme inhibitors have now been shown to improve outcomes in hypertensive patients, an effect that may in part be related to the vascular protective effects reviewed here.

Activation of astroglial phospholipase D activity by phorbol ester involves ARF and Rho proteins

Primary cultures of rat cortical astrocytes express phospholipase D (PLD) isoforms 1 and 2 as determined by RT-PCR and Western blot. Basal PLD activity was strongly (10-fold) increased by 4beta-phorbol-12beta,13alpha-dibutyrate (PDB) (EC(50): 56 nM), an effect which was inhibited by Ro 31-8220 (0.1-1 microM), an inhibitor of protein kinase C (PKC), and by brefeldin A (10-100 microg/ml), an inhibitor of ADP-ribosylating factor (ARF) activation. Pretreatment of the cultures with Clostridium difficile toxin B-10463 (0.1-1 ng/ml), which inactivates small G proteins of the Rho family, led to a breakdown of the astroglial cytoskeleton; concomitantly, PLD activation by PDB was reduced by up to 50%. In contrast, inactivation of proteins of the Ras family by Clostridium sordellii lethal toxin 1522 did not affect PLD activation. In parallel experiments, serum-induced PLD activation was sensitive to brefeldin A, but not to Ro 31-8220 and not to clostridial toxins. We conclude that, in astrocytes, the PLD isoform which is activated by phorbol ester requires PKC, ARF and Rho proteins for full activity and probably represents PLD1.

Intracellular accumulation of ascorbic acid is inhibited by flavonoids via blocking of dehydroascorbic acid and ascorbic acid uptakes in HL-60, U937 and Jurkat cells

In HL-60, U937 and Jurkat cells, the intracellular accumulation of ascorbic acid occurred via uptakes of both dehydroascorbic acid (an oxidized metabolite of ascorbic acid) and ascorbic acid (vitamin C). Dehydroascorbic acid and ascorbic acid were transported into cells by sodium-independent glucose transporters (GLUT 1 and GLUT 3) and sodium-dependent ascorbic acid transporters, respectively. Flavonoids inhibited the intracellular accumulation of ascorbic acid by blocking dehydroascorbic acid and ascorbic acid uptakes in the transformed cells. At flavonoid concentrations of 10-70 micromol/L, approximately 50% of dehydroascorbic acid uptake was inhibited in the cells. In Jurkat cells, two potent flavonoids (myricetin and quercetin) competitively inhibited dehydroascorbic acid uptake, and K(i) values were approximately 14 and 15 micromol/L, respectively. Because GLUT 1 and GLUT 3 transport dehydroascorbic acid, the inhibition of dehydroascorbic acid uptake by flavonoids was investigated by using Chinese hamster ovary cells overexpressing rat GLUT 1 or human GLUT 3. Myricetin at concentrations of 22 and 18 micromol/L, respectively, inhibited half of dehydroascorbic acid uptake in the cells overexpressing GLUT 1 and GLUT 3. Myricetin also inhibited ascorbic acid uptake; inhibition was noncompetitive with K(i) = 14 micromol/L in Jurkat cells. These data indicate that flavonoids inhibit both ascorbic acid and dehydroascorbic acid uptake but do so by different mechanisms. These data may contribute to new understanding of the biological effect of flavonoids on the intracellular accumulation of ascorbic acid in human cells.

Intraosseous calcifying pseudotumor of the axis: a case report

STUDY DESIGN

A case report and review of the literature.

OBJECTIVE

To present the first case of intraosseous calcifying pseudotumor arising from the axis.

SUMMARY OF BACKGROUND DATA

Calcifying pseudotumor is a very rare disease. Only 24 cases have been previously reported.

METHODS

A case of calcifying pseudotumor involving the body, dens, and laminae of the axis in a 60-year-old male patient was managed with total laminectomy of the axis and instrumented occipitocervical fusion, followed by the curettage of the body and dens of the axis and autogenous iliac bone graft. Medical records, imaging studies, microscopic findings, and related literature are reviewed.

RESULTS

Microscopic examination showed amorphous, basophilic, and chondroid calcifying masses surrounded with palisading histiocytes and foreign body-type giant cells. The findings were consistent with those of calcifying pseudotumors previously reported in other sites of the body. At 24 months after operation, a significant reduction of neck pain was achieved. But there was evidence of local recurrence of the lesion in the body and dens of the axis with a local progression of the preexisting lesion in the facet joints.

CONCLUSION

This is the first report of intraosseous calcifying pseudotumor arising from the axis.

Correction of arterial structure and endothelial dysfunction in human essential hypertension by the angiotensin receptor antagonist losartan

BACKGROUND

Structural and functional alterations of the vasculature may contribute to complications of hypertension. Because angiotensin II may be pivotal in some of these vascular abnormalities, we tested the hypothesis that the angiotensin type 1 (AT(1)) receptor antagonist losartan, in contrast to the beta-blocker atenolol, would correct resistance artery abnormalities in patients with essential hypertension.

METHODS AND RESULTS

Nineteen untreated patients with mild essential hypertension (47+/-2 years, range 30 to 65 years; 57% male) were randomly assigned in double-blind fashion to losartan or atenolol treatment for 1 year. Nine age/sex-matched normotensive subjects were also studied. Both treatments reduced blood pressure to a comparable degree (losartan, from 149+/-4.1/101+/-1.6 to 128+/-3.6/86+/-2.2 mm Hg, P<0.01; atenolol, from 150+/-4.0/99+/-1.2 to 130+/-3.2/84+/-1.4 mm Hg, P<0.01). Resistance arteries (luminal diameter 150 to 350 microm) dissected from gluteal subcutaneous biopsies were studied on a pressurized myograph. After 1 year of treatment, the ratio of the media width to lumen diameter of arteries from losartan-treated patients was significantly reduced (from 8.4+/-0.4% to 6.7+/-0.3%, P<0.01). Arteries from atenolol-treated patients exhibited no significant change (from 8. 3+/-0.3% to 8.8+/-0.5% after treatment). Endothelium-dependent relaxation (acetylcholine-induced) was normalized by losartan (from 82.1+/-4.9% to 94.7+/-1.1%, P<0.01) but not by atenolol (from 80. 4+/-2.7% to 81.7+/-4.6%). Endothelium-independent relaxation (by sodium nitroprusside) was unchanged after treatment.

CONCLUSIONS

The AT(1) antagonist losartan corrected the altered structure and endothelial dysfunction of resistance arteries from patients with essential hypertension, whereas the beta-blocker atenolol had no effect.

An in vitro assessment of the flow characteristics of spiral-ridged and smooth-walled JJ ureteric stents

OBJECTIVE

To assess drainage through spiral-ridged and smooth-walled JJ ureteric stents (designed to ensure upper tract drainage) and thus determine whether drainage preferentially occurs around rather than through the spiral-ridged stent, promoting renal flow and potentially facilitating the passage of urinary stone fragments. Materials and methods A mechanical ureteric model was constructed to mimic the funnel characteristics of the renal pelvis. A motor pump was used to help simulate respiratory and skeletal movement, resulting in differential motion between the intraluminal stent and the surrounding ureteric wall. Tubes of varying internal diameters were used to simulate different sizes of ureter. Flow rates of standard 7 F smooth-walled stents were compared with 7 F spiral-ridged stents with and without occluded lumens, and with and without standardized excursions.

RESULTS

Extraluminal flow (mean rates) with and without movements simulating respiratory excursions were significantly higher with the spiral stent for all stent diameters evaluated. All flow rates increased as the ureteric diameter increased. Total flow past the spiral stent was significantly greater than flow with the smooth-walled stent under all conditions tested. Flows measured around the spiral stent under conditions of excursion were the highest of all categories, 20-fold higher than in smooth-walled, closed, stationary stents.

CONCLUSION

Spiral-ridged JJ stents provided substantially greater flow in this in vitro model. Extraluminal flow was markedly increased with the spiral-ridged configuration. The difference in flow rates was more pronounced at the smaller pseudo-ureteric tube diameters, simulating dimensions found in clinical practice. The flow rate also was increased when the central lumen remained open, and was greater still when there was dynamic excursion with respiratory movements.

Synovial cyst of the transverse ligament of the atlas in a patient with os odontoideum and atlantoaxial instability

STUDY DESIGN

A case report and review of the literature.

OBJECTIVE

To describe the diagnosis and successful treatment of a synovial cyst arising from the transverse ligament in a patient with os odontoideum and atlantoaxial instability.

SUMMARY OF BACKGROUND DATA

Synovial cysts arising from the transverse ligament of the atlas are extremely rare. Development of a synovial cyst is thought to be attributable to degenerative changes of the C1-C2 facet joints or to microtrauma. Direct excision of the cyst is the only treatment cited in previous reports.

METHODS

A synovial cyst arising from the transverse ligament of the atlas in a 45-year-old man with os odontoideum and atlantoaxial instability was treated surgically with posterior atlantoaxial fusion alone. The magnetic resonance images, surgical treatment, and related literature are reviewed.

RESULTS

Preoperative magnetic resonance images of the cervical spine showed a large cystic mass located ventral to the cord arising at the level of the transverse ligament of the atlas: the mass was of low signal intensity on T1-weighted images, was of high signal intensity on T2-weighted images, and was enhanced marginally with gadolinium-DTPA on T1-weighted images. Spontaneous regression of the cyst was identified on the follow-up magnetic resonance images taken 3 months after C1-C2 posterior wiring and fusion.

CONCLUSIONS

A patient with a synovial cyst arising at the C1-C2 junction ventrally at the level of the transverse ligament showed spontaneous regression of the lesion after C1-C2 posterior wiring and fusion.

Reduction of resistance artery stiffness by treatment with the AT(1)-receptor antagonist losartan in essential hypertension

In spontaneously hypertensive rats resistance artery structure, endothelial dysfunction and geometry-independent wall stiffness were reduced by an angiotensin AT(1)-receptor antagonist. In previous studies of human hypertension, interruption of the renin-angiotensin system corrected small artery structure and endothelial dysfunction, whereas the beta-blocker atenolol did not. We hypothesized that the AT(1)R antagonist losartan, but not the beta-blocker atenolol, would reduce stiffness of gluteal subcutaneous small arteries in essential hypertensive patients. Seventeen untreated mild essential hypertensive patients (47+/-2 years; 75% male) were randomly assigned in double-blind fashion to losartan or atenolol treatment for one year. Small, resistance size arteries were studied on pressurized myographs. Blood pressure (mmHg) was reduced (p<0.01) from 145 +/- 4/101 +/- 2 and 147 +/- 6/98 +/- 2 to 128 +/- 4/86 +/- 2 and 131 +/- 3/84 +/- 1 by losartan and atenolol, respectively. The media/lumen ratio of small arteries was unaffected by atenolol (8.3+/-0.3% before and 8.8+/-0.5% after treatment). In contrast, losartan reduced media/lumen ratio from 8.4+/-0.4% to 6.7+/-0.3% (p<0.01). Whereas isobaric elastic modulus was unaffected by either treatment, geometry-independent stiffness (slope of elastic modulus vs. stress) was reduced from 9.7+/-1.2 to 6.1+/-0.9 (P<0.05) under losartan treatment, but was unchanged by atenolol (8.2+/-1.3 to 7.8+/-0.6). In conclusion, treatment with losartan reduced stiffness and structural alterations of subcutaneous resistance arteries of previously untreated essential hypertensive patients, whereas atenolol failed to do so.

The activation of B-Raf and Raf-1 after electroconvulsive shock in the rat hippocampus

We demonstrated that ECS activates the kinase activity of B-Raf and Raf-1 in the rat hippocampus. The activity was maximal at one minute after ECS and temporally coincided with the increased membrane translocation of Rafs and the reported activity of MAPK, but not with the phosphorylation of Rafs.

Characterization of the promoter of the human ribonucleotide reductase R2 gene

We describe here cloning and characterization of the promoter region of the human ribonucleotide reductase R2 gene. Primer extension and sequence data indicated that two different transcripts were produced via using two different promoter regions. Promoter activity of the 5' flanking region of the first transcript was approximately 100-fold higher than controls, and that of the second transcript was approximately 30-fold higher than controls. Particularly, the proximal region of the first transcript, -125 to +1 bp, was responsible for approximately a 50-fold increase in promoter activity, compared to controls. This region had three CCAAT sequences, each of which contributed similarly to promoter activity. When all three CCAAT sequences were mutated, promoter activity declined 80%. In addition, the promoter region -125 to +1 bp was responsible for cell-cycle-specific expression. These data provided essential information concerning regulatory mechanisms of cell-cycle-specific expression of human ribonucleotide reductase R2.

Mechanism for inactivation of the KIP family cyclin-dependent kinase inhibitor genes in gastric cancer cells

The mechanism for inactivation of the KIP family cyclin-dependent kinase inhibitor (CDKI) genes, the p21, p27, and p57 genes, in gastric cancer cells was tested by treating the cells with either the DNA demethylation agent, 5-aza-2'-deoxycytidine or the histone deacetylase inhibitor, n-butyric acid or trichostatin A. RNA expression of the gene was determined by reverse transcription PCR. The p21 gene was activated only by histone deacetylase inhibitor. The p57 gene was activated by histone deacetylase inhibitors in all of the gastric cancer cell lines and by 5-aza-2'-deoxycytidine in five of eight gastric cell lines. However, the p27 gene was not inactivated in gastric cancer cell lines. The methylation status of the promoter of the p21 and p57 genes was also tested by digestion with the methylation-sensitive restriction enzymes and a subsequent PCR. The promoter of the p21 gene has no methylation. The promoter of the p57 gene is, however, methylated in five of eight gastric cancer cell lines as expected from the result of the treatment with 5-aza-2'-deoxycytidine. Formation of the inactive chromatin through histone deacetylation seems to be the general mechanism for inactivation of both the p21 and the p57 genes in gastric cancer cells. Hypermethylation of promoter region seems to be an alternative pathway for inactivation of the p57 gene.

Inhibition of trifluoperazine-induced DNA fragmentation by cyclic AMP mediated signaling

Trifluoperazine (TFP), a phenothiazine antipsychotic agent with calmodulin antagonist property, induces DNA fragmentation in a dose- and time-dependent manner in PC12 cells. Various agents affecting calcium mediated intracellular signal transduction such as calcium chelators, calcium ionopores, inhibitors of phospholipase C, and activators/inhibitors of protein kinase C did not block TFP-induced DNA fragmentation. Some of these agents themselves induced DNA fragmentation in the conditions under which they were examined. However, cholera toxin (selective Gs activator), forskolin (adenylate cyclase activator) or dibutyryl cyclic AMP (cyclic AMP analogue) inhibited TFP-induced DNA fragmentation in a dose-dependent manner. These results suggest that it is not the calcium but the Gs and adenylate cyclase pathways that play an important role in TFP-induced DNA fragmentation in PC12 cells.

Antithrombotic activities of green tea catechins and (-)-epigallocatechin gallate

The antithrombotic activities and mode of action of green tea catechins (GTC) and (-)-epigallocatechin gallate (EGCG), a major compound of GTC, were investigated. Effects of GTC and EGCG on the murine pulmonary thrombosis in vivo, human platelet aggregation in vitro, and ex vivo, and coagulation parameters were examined. GTC and EGCG prevented death caused by pulmonary thrombosis in mice in vivo in a dose-dependent manner. They significantly prolonged the mouse tail bleeding time of conscious mice. They inhibited adenosine diphosphate- and collagen-induced rat platelet aggregation ex vivo in a dose-dependent manner. GTC and EGCG inhibited ADP-, collagen-, epinephrine-, and calcium ionophore A23187-induced human platelet aggregation in vitro dose dependently. However, they did not change the coagulation parameters such as activated partial thromboplastin time, prothrombin time, and thrombin time using human citrated plasma. These results suggest that GTC and EGCG have the antithrombotic activities and the modes of antithrombotic action may be due to the antiplatelet activities, but not to anticoagulation activities.

Development of a non-transformed human liver cell line with differentiated-hepatocyte and urea-synthetic functions: applicable for bioartificial liver

There is a need to develop human hepatocyte cell lines which retain both replicating capacity and highly differentiated functions to facilitate the development of an efficient bioartificial liver. The present study was undertaken to differentiate, using sodium butyrate, the actively replicating immortalized human liver cell line. The effects of butyrate on cell growth and cell cycle were analyzed, and the albumin synthesis, cytochrome P450 and ammonia-detoxifying activity of the butyrate-treated cells were measured. Butyrate treatment resulted in G2/M arrest of the cell cycle and polygonal changes in the cell morphology. Neither the control nor the butyrate-treated cells showed transformed characteristics. Butyrate treatment increased the amount of albumin secretion, cytochrome P450 activity, and the urea production rate of the cells. The present study provides non-transformed human hepatocytes, which can replicate unlimitedly and then restore differentiated hepatocyte-specific functions by butyrate, and therefore, have applications for the development of an efficient bioartificial liver.

A qualitative process system for modeling NF-kappaB and AP-1 gene regulation in immune cell biology research

An experiment-oriented integrated model of the regulation of the biologically ubiquitous NF-kappaB and AP-1 gene transcription promoters was built by extending a previously developed qualitative process system for simulating cell behavior in the immune system. The core knowledge base (KB) implemented a deep biological ontology including molecular, ultrastructural, cytological, histological, and organismic definitions. KB states, relationships, predicates, and heuristics also represented process interactions between reactive oxygen species, growth factors, and a variety of kinases phosphorylating intermediate molecules in the NF-kappaB and AP-1 regulatory signaling pathways. The system successfully simulated the molecular process steps underlying outcomes of eight different molecular genetics laboratory experiments, including those dealing with NF-kappaB and AP-1 regulation in immunodeficiency virus infection and tumor necrosis factor responses.

Characterization of two fungal-elicitor-induced rice cDNAs encoding functional homologues of the rab-specific GDP-dissociation inhibitor

By using the mRNA differential display approach to isolate defense signaling genes active at the early stage of fungal infection two cDNA fragments with high sequence homology to rab-specific GDP-dissociation inhibitors (GDIs) were identified in rice (Oryza sativa L.) suspension cells. Using polymerase-chain-reaction products as probes, two full-length cDNA clones were isolated from a cDNA library of fungal-elicitor-treated rice, and designated as OsGDI1 and OsGDI2. The deduced amino acid sequences of the isolated cDNAs exhibited substantial homology to Arabidopsis rab-GDIs. Northern analysis revealed that transcripts detected with the 3'-gene-specific DNA probes accumulated to high levels within 30 min after treatment with a fungal elicitor derived from Magnaporthe grisea. The functionality of the OsGDIs was demonstrated by their ability to rescue the Sec19 mutant of Saccharomyces cerevisiae which is defective in vesicle transport. The proteins, expressed in Escherchia coli, cross-reacted with a polyclonal antibody prepared against bovine rab-GDI. Like bovine rab-GDI, the OsGDI proteins efficiently dissociated rab3A from bovine synaptic membranes. Using the two-hybrid system, it was shown that the OsGDIs specifically interact with the small GTP-binding proteins belonging to the rab subfamily. The specific interaction was also demonstrated in vitro by glutathione S-transferase resin pull-down assay.

Dissociation of RalA from synaptic membranes by Ca2+/calmodulin

Ras-related small GTP-binding proteins execute many cellular functions, such as cell growth, differentiation, cytoskeletal reorganization, membrane trafficking, and membrane fusion. RalA belongs to the superfamily of Ras-related small GTP-binding proteins. Synaptic vesicles (SV) contain small GTP-binding proteins, where RalA, Rab3A, and Rab5A are the major GTP-binding proteins. It has been postulated that a cycling of these proteins between membrane-bound and soluble states is required for regulating cellular functions. Calmodulin (CaM) was found to dissociate Rab3A from SV membranes by forming a 1:1 complex with Ca2+/CaM. RalA was also found to be a Ca2+/CaM-binding protein. Therefore, we examined if Ca2+/CaM can also cause the RalA to dissociate from SV membranes. In this study, we identified that Ca2+/CaM dissociates RalA as well as Rab3A from synaptic vesicles.

Blood pressure and small arteries in DOCA-salt-treated genetically AVP-deficient rats: role of endothelin

Hypertension is associated with structural and mechanical abnormalities of resistance arteries. We have recently reported that vasopressin may be involved in the blood pressure elevation and remodeling of resistance arteries in deoxycorticosterone acetate (DOCA)-salt hypertension, perhaps by modulating vascular endothelin-1 expression. We tested this hypothesis further by examining DOCA-salt hypertension in homozygous vasopressin-deficient Brattleboro (BB) rats in comparison with Long-Evans (LE; control) rats. Mesenteric resistance arteries (lumen <300 microm) were studied on pressurized myographs. After 5 weeks, systolic blood pressure was greater in LE DOCA-salt-treated rats (189+/-5 mm Hg) compared with uniephrectomized (UNx) LE control rats (117+/-4 mm Hg; P<0.01). The increase in blood pressure induced by DOCA-salt treatment was attenuated in vasopressin-deficient rats, such that BB DOCA-salt-treated rats exhibited only a slight elevation of blood pressure (134+/-6 mm Hg) compared with BB-UNx rats (111+/-4 mm Hg; P<0.05). Resistance arteries in LE DOCA-salt-treated rats had a smaller lumen diameter and a larger media width, media cross-sectional area, and media-lumen ratio compared with LE-UNx rats. Isobaric stiffness was unaltered in resistance arteries from LE DOCA-salt-treated rats, despite stiffening of the arterial wall components as indicated by a significant increase in the slope of the media stress-incremental elastic modulus relationship. DOCA-salt treatment in the absence of endogenous vasopressin, ie, in homozygous di/di BB rats, failed to alter vascular structure or wall component stiffness and resulted in a lesser degree of blood pressure elevation. Reverse transcription-polymerase chain reaction analysis revealed that DOCA-salt treatment enhanced endothelin gene expression in LE rats but failed to do so in BB rats. These data indicate that vasopressin plays a critical role in modulating vascular structure and mechanics, as well as blood pressure, in DOCA-salt-induced hypertension. Moreover, these effects of vasopressin are in part mediated by enhancement of endothelin expression.

Phosphatidic acid is important to the translocation of Rab3A from the cytosol to phospholipid membranes

RAB3A, a Ras-related GTP-binding protein, is found in a rat neuronal cytosol in the form of complex with RabGDI or located on the synaptic vesicles and it cycles between the cytosol and the membranes. However, the regulatory mechanism of the translocation of Rab3A has not been clearly understood. To understand the mechanism of the translocation of Rab3A from the cytosol to the membranes, we examined which membranenous phospholipid is required for the translocation of Rab3A. Phosphatidic acid (PA) was found to be required for the translocation of Rab3A to the membranes and GTPgammaS stimulated the translocation of Rab3A.

Biomechanical and morphometric analysis of hydroxyapatite-coated implants with varying crystallinity

PURPOSE

The level of crystallinity in hydroxyapatite (HA) is thought to be responsible for its degradation in the physiologic milieu. The purpose of this study was to compare the in vivo bony response to HA coatings of varying levels of crystallinity and determine the optimum composition for promoting osseointegration.

MATERIALS AND METHODS

Cylindrical implants of sand-blasted CP titanium and HA-coated titanium of 50% (low), 70% (medium), and 90% (high) crystallinity were inserted into the canine femur for 1, 4, 12, and 26 weeks. Morphometric analysis of undecalcified sections determined the percentage of bone contact with the implant surface. A pullout test was used to measure the interfacial attachment strength of the bone-implant interface. Scanning electron microscope (SEM) examination of the implant surface aided in identifying the failure mode. Coating thickness was measured under light microscopy to determine whether degradation occurred.

RESULTS

No significant differences could be found in the percentage of bone contact and interfacial attachment strength between the three types of HA-coated implants throughout the four implantation periods. A significantly higher percentage of bone contact on HA-coated implants than on uncoated titanium implants was noted at 4 weeks. (ANOVA, P<.05). HA-coated implants were also found to have significantly higher interfacial attachment strength than titanium implants at 4, 12, and 26 weeks. Coating thickness decreased gradually with time. The most noticeable reduction was found on the low-crystallinity coatings during the first 4 weeks. Failure of the bone-coating-implant complex occurred mostly within the coating or near the coating-implant interface.

CONCLUSIONS

HA coatings on metal implants enhance osseointegration in the early stage of bone healing and provide strong bone-bonding capability, although titanium implants had about the same level of bone contact in the later stage of healing. Crystallinity of HA coatings has no significant influence over the bone formation capacity and the bone bonding strength. However, an HA coating of higher crystallinity is more desirable in providing durability and maintaining osteoconductive properties.

Differential activation of c-Jun N-terminal protein kinase and p38 in rat hippocampus and cerebellum after electroconvulsive shock

Electroconvulsive shock (ECS), an effective treatment for psychiatric diseases, has been reported to induce immediate-early genes (IEGs) and to activate p42 and p44 MAPKs (ERK-1 and ERK-2) in rat brain. In this study, we examined the activation of the other members of MAPK family, c-Jun N-terminal protein kinase (JNK/SAPK) and p38. Following ECS, the phosphorylation of p38 was substantially increased in both hippocampus and cerebellum, but the increase of JNK phosphorylation was observed only in hippocampus. We also investigated the phosphorylation of their upstream kinases, SEK-1, MKK6 and MKK3. In both hippocampus and cerebellum, the phosphorylation of MKK6 showed closer correlation with p38 phosphorylation than that of MKK3. However, SEK-1, known as upstream kinase of JNK and p38 in vitro, corresponded with none of MAPKs. These results, with previous reports on the activation of ERK, indicate that ECS activates three MAPKs differentially in rat hippocampus and cerebellum, and suggest the possibility that unknown MAPKK may be involved in the activation of JNK in rat brain after ECS.

Phosphorylation and activation of phospholipase D1 by protein kinase C in vivo: determination of multiple phosphorylation sites

Protein kinase C (PKC) is an important regulator of phospholipase D1 (PLD1). Currently there is some controversy about a phosphorylation-dependent or -independent mechanism of the activation of PLD1 by PKC. To solve this problem, we examined whether PLD1 is phosphorylated by PKC in vivo. For the first time, we have now identified multiple basal phophopeptides and multiple phorbol myristate acetate (PMA) induced phosphopeptides of endogenous PLD1 in 3Y1 cells as well as of transiently expressed PLD1 in COS-7 cells. Down regulation or inhibition of PKC greatly attenuated the PMA-induced phosphorylation as well as the activation of PLD1. In the presence of PMA, purified PLD1 from rat brain was also found to be phosphorylated by PKCalpha in vitro at multiple sites generating seven distinct tryptic phosphopeptides. Four phosphopeptides generated in vivo and in vitro correlated well with each other, suggesting direct phosphorylation of PLD1 by PKCalpha in the cells. Serine 2, threonine 147, and serine 561 were identified as phosphorylation sites, and by mutation of these residues to alanine these residues were proven to be specific phosphorylation sites in vivo. Interestingly, threonine 147 is located in the PX domain and serine 561 is in the negative regulatory "loop" region of PLD1. Mutation of serine 2, threonine 147, or serine 561 significantly reduced PMA-induced PLD1 activity. These results strongly suggest that phosphorylation plays a pivotal role in PLD1 regulation in vivo.

Production and characterization of isotype-specific monoclonal antibodies to bovine brain Rab GDI

Small GTPases of the Rab family play a key role in controlling vesicular transport, and the Rab GDP-dissociation inhibitor (GDI) is a regulatory protein for the Rab proteins. Here we report the production and characterization of isotype-specific monoclonal antibodies (MAbs) to Rab GDI. Rab GDI was purified from bovine brain in several steps of column chromatography and was injected into BALB/c mice intraperitoneally. The resulting MAbs specifically recognized a single protein band of 55 kDa, which comigrates with purified bovine Rab GDI. To localize Rab GDI, we processed cells from different sources for indirect immunofluorescence microscopy. Interestingly, the MAb stained cytosol and vesicular structures in brain cells, whereas it predominantly stained cytosol in nonbrain cells. Next, we investigated the cross-reactivities of brain Rab GDI from some mammals. The immunoreactive bands on Western blots appeared to be the same in molecular mass, 55 kDa, in all mammalian species tested including human. In summary, we produced a panel of MAbs that are GDI-alpha/1 form-specific and we believe that the MAbs will be valuable tools in elucidating the function of Rab GDI isoforms.

Flavonoids are potential inhibitors of glucose uptake in U937 cells

Flavonoids are a group of polyphenolic compounds ubiquitously found in plants including fruits, and vegetables. Broad ranges of the biological activities of flavonoids have been reported using in vitro studies. I report that several natural flavonoids blocked glucose uptake in myelocytic U937 cells. Although there were some variations in the blocking activity of individual flavonoids, approximately half of the glucose uptake was blocked by flavonoids at the concentrations of 8-50 microM. The decreasing order of the blocking activity was fisetin >/= myricetin >/= quercetin >/= apigenin > genistein > cyanidin > daidzein >/= hesperetin > naringenin > catechin. Fisetin showed approximately 50% inhibition of glucose uptake at a concentration of 8 microM. Similar patterns of the inhibition were observed in lymphocytic Jurkat cells. Fisetin and quercetin inhibited glucose transport in a competitive manner. K(i) values for fisetin and quercetin were proximately 9 and 12 microM, respectively. This study showed that some types of natural flavonoids block glucose uptake in U937 cells and that natural flavonoids could be used as alternative blockers of glucose uptake in vitro.

Deposition of eosinophil-granule major basic protein and expression of intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 in the mucosa of the small intestine in infants with cow's milk-sensitive enteropathy

BACKGROUND

Cow's milk-sensitive enteropathy (CMSE) is an important cause of chronic diarrhea and failure to thrive in infancy. The immunopathology of the mucosal lesion associated with CMSE has not yet been described.

OBJECTIVES

This study investigated the eosinophil activation and the role of adhesion molecules in the pathogenesis of intestinal mucosal damage associated with CMSE.

METHODS

Twenty-one patients with chronic diarrhea and abnormal mucosa on duodenal biopsy specimens were included. The patients had negative responses to skin prick tests and RASTs with milk. Fourteen patients were diagnosed with CMSE by milk challenge test and were designated as the CMSE group. Seven patients with no milk intolerance were defined as the non-CMSE group. Four infants with frequent vomiting and no mucosal abnormalities were also studied as the control group. Immunohistochemical stains for eosinophil major basic protein (MBP), vascular cell adhesion molecule-1 (VCAM-1), and intercellular adhesion molecule-1 on endoscopic duodenal biopsy specimens were performed.

RESULTS

The degree of eosinophil degranulation, as evidenced by localization of extracellular MBP, was significantly greater in the CMSE group compared with the non-CMSE and control groups (P <.05). Expression of VCAM-1 on mononuclear cells was higher in the CMSE group compared with the non-CMSE and control groups (P <.05). The severity of villous atrophy was positively correlated with the deposition of MBP (r = 0.79, P <.001).

CONCLUSION

These results strongly suggest eosinophils and VCAM-1 are implicated in the pathogenesis of mucosal damage associated with CMSE.

Criteria and recommendations for vitamin C intake

Recommendations for vitamin C intake are under revision by the Food and Nutrition Board of the National Academy of Sciences. Since 1989 when the last recommended dietary allowance (RDA) of 60 mg was published, extensive biochemical, molecular, epidemiologic, and clinical data have become available. New recommendations can be based on the following 9 criteria: dietary availability, steady-state concentrations in plasma in relationship to dose, steady-state concentrations in tissues in relationship to dose, bioavailability, urine excretion, adverse effects, biochemical and molecular function in relationship to vitamin concentration, direct beneficial effects and epidemiologic observations in relationship to dose, and prevention of deficiency. We applied these criteria to the Food and Nutrition Board's new guidelines, the Dietary Reference Intakes, which include 4 reference values. The estimated average requirement (EAR) is the amount of nutrient estimated to meet the requirement of half the healthy individuals in a life-stage and gender group. Based on an EAR of 100 mg/d of vitamin C, the RDA is proposed to be 120 mg/d. If the EAR cannot be determined, an adequate intake (AI) amount is recommended instead of an RDA. The AI was estimated to be either 200 mg/d from 5 servings of fruits and vegetables or 100 mg/d of vitamin C to prevent deficiency with a margin of safety. The final classification, the tolerable upper intake level, is the highest daily level of nutrient intake that does not pose risk or adverse health effects to almost all individuals in the population. This amount is proposed to be less than 1 g of vitamin C daily. Physicians can tell patients that 5 servings of fruits and vegetables per day may be beneficial in preventing cancer and providing sufficient vitamin C intake for healthy people, and that 1 g or more of vitamin C may have adverse consequences in some people.

Application of extracorporeal shock wave lithotripter (ECSWL) in orthopaedics. II. Dose-response and pressure distribution measurements

In order to apply the extracorporeal shock wave lithotripter (ECSWL) technique to the loosening of the bone-cement interface for the extraction of the cement during revision arthroplasty it is essential to know the dose-response characteristics. The present study shows that the number of shocks needed to break the interface between a 2- and 6-mm-thick bovine femoral bone and bone cement is similar to the fatigue behavior of a material, that is, Log(N) = C(kV) + D, where N is the number of shock impulses, kV is the power setting of the lithotripter machine in kilovolts, and C and D are constants. Iso-pressure distribution of the traveling shock wave front through a simulated bone in a Plexiglass tube using Fuji pressure film showed quantitative pressure contours from which one can understand the effective area of shock wave and its distribution. The most effective area of the shock wave was about 1.5 cm in diameter at 23 and 25 kV with pressure at least 7.0 MPa which is more than sufficient to break the bone-cement interface in tension.

Application of extracorporeal shock wave lithotripter (ECSWL) in orthopaedics. III. In vitro and in vivo studies

The present study was conducted to compare the push-out strength of the treated and control samples obtained after implantation of intramedullary rod in canine femurs with bone cement to simulate the femoral stem implantation for 2 weeks, 3 and 6 months. Contralateral femur served as control. The result showed a significant decrease in push-out interfacial strength after shock wave treatment (average 48.4% decrease compared with control, p less than 0.0001) which is similar to the in vitro results. There was no significant difference if the shock treatment was applied and left for 2 weeks or 4 weeks compared to the ones tested immediately after sacrifice. There were some soft tissue damage immediately following shock treatment in the focal area but this returned to normal in 2 weeks. Human cadaveric femoral bone experiment results showed that results are similar for both human cadaveric femoral bones and the canine bone (the dosage level was higher for the human bone than canine). The number of impacts used to extract the bone cement plug out of a human femur segment (5-cm long) decreased about 68% at 23 and 25 kV treatment power level. These preliminary studies indicate that the shock wave can be utilized to reduce the interfacial strength of the bone and bone cement although more studies are needed to assess its efficacy in terms of cost, long-term effect on patients and the exact mechanism of the loosening before this technique can be used clinically.

Application of extracorporeal shock wave lithotripter (ECSWL) in orthopedics. I. Foundations and overview

In this paper we have reviewed the feasibility of using a shock wave lithotripter to loosen the interface between the bone and acrylic bone cement for revision arthroplasty. We have reviewed the physics of shock wave and its applications in medicine, especially its interaction with tissues. The calculations show that the energy is greatly reduced at the interface both in the soft tissue-bone interface and cement-bone interface. On the other hand, a tensile and compressive pressure can be operated at the cement-bone interface that can cause the interface to break if the pressure exceeds the tensile strength of the cement-bone interface. Subsequent papers will deal with in vitro and in vivo application of the shock wave in the treatment of the cement from the intramedullary canal.

Effect of thermal treatment on heating characteristics of Ni-Cu alloy for hyperthermia: preliminary studies

Ferromagnetic Ni-Cu alloy wires were characterized in order to obtain well-defined thermoseeds for application in interstitial hyperthermia of prostate cancer. Thermoseeds have been produced which possess Curie points in the therapeutic hyperthermia range, approximately 40 to 50 degrees C. The effect of thermal treatment and composition on the heating characteristics of the thermoseeds were investigated. The preliminary study shows that the recrystallization is crucial for altering thermoseeds' heating characteristics. Obtaining thermoseeds which behave as desired depends on changes in annealing times and temperatures. One may increase the maximum heating temperature (similar to Curie temperature) by increasing the annealing time and cooling time. Decreasing the lower annealing plateau temperature also increases the maximum seed heating temperature. Higher nickel content compositions did not affect rise time but increased the maximum heating temperature.

Phospholipase D1 in caveolae: regulation by protein kinase Calpha and caveolin-1

Caveolae are small plasma membrane invaginations that have been implicated in cell signaling, and caveolin is a principal structural component of the caveolar membrane. Previously we have demonstrated that protein kinase Calpha (PKCalpha) directly interacts with phospholipase D1 (PLD1), activating the enzymatic activity of PLD1 in the presence of phorbol 12-myristate 13-acetate (PMA) [Lee, T. G., et al. (1997) Biochim. Biophys. Acta 1347, 199-204]. In this study, using a detergent-free procedure for the purification of a caveolin-enriched membrane fraction (CEM) and immunoblot analysis, we show that PLD1 is enriched in the CEMs of 3Y1 rat fibroblasts. Purified PLD1 directly bound to a glutathione S-transferase-caveolin-1 fusion protein in in vitro binding assays. The association of PLD1 with caveolin-1 could be completely eliminated by preincubation of PLD1 with an oligopeptide corresponding to the scaffolding domain (amino acids 82-101) of caveolin-1, indicating that caveolin-1 interacts with PLD1 through the scaffolding domain. The peptide also inhibited PKCalpha-stimulated PLD1 activity and the interaction between PLD1 and PKCalpha with an IC50 of 0.5 microM. PMA elicits translocation of PKCalpha to the CEMs, inducing PLD activation through the interaction of PKCalpha with PLD1 in the CEMs. Caveolin-1 also coimmunoprecipitated with PLD1 in the absence of PMA, and the amounts of coimmunoprecipitated caveolin-1 decreased in response to treatment with PMA. Taken together, our results suggest a new mechanism for the regulation of the PKCalpha-dependent PLD activity through the molecular interaction between PLD1, PKCalpha, and caveolin-1 in caveolae.

Application of biological monitoring to the quantitative exposure assessment for neuropsychological effect by chronic exposure to organic solvents

OBJECTIVE

Quantitative exposure assessment became more common as a result of attempts to reduce nondifferential exposure misclassification and to observe a steeper exposure-response relationship. Several exposure variables were compared in a demonstration of the exposure-response relationship between neuropsychological abnormality and long-term exposure to organic solvents in workers at one shipyard.

METHOD

Environmental monitoring and biological monitoring were performed to evaluate the exposure of the workers to organic solvents. Cumulative exposure (CE) and lifetime-weighted average exposure variables were developed with both environmental and biological monitoring data. A neuropsychological questionnaire and a function test for confirmation of a disorder or dysfunction in attention, executive function, visuospatial, and constructional abilities, learning and memory, and psychomotor function were performed.

RESULTS

The abnormal rate in neuropsychological diagnosis was 9.3% in the exposed group, which was much higher than the 2.1% rate obtained in the nonexposed group (P<0.01). The neuropsychological abnormal rate showed a significant dose-response association with CE created with biological monitoring data. The results also suggest that biological monitoring can provide impressive and effective information for quantitative exposure assessment, even in epidemiology studies.

Phospholipase D1 is located and activated by protein kinase C alpha in the plasma membrane in 3Y1 fibroblast cell

The subcellular location of phospholipase D1 (PLD1) and its activation by protein kinase C alpha (PKC alpha) were examined by subcellular fractionation and by microscopic observation of green fluorescent protein-fused PLD1 (GFP-PLD1) or PKC alpha (GFP-PKC alpha) in fibroblastic 3Y1 cells. Major PLD1 immunoreactivity and PKC alpha-stimulated PLD activity segregated with a plasma membrane marker, even though a significant amount was co-fractionated with markers for endoplasmic reticulum (ER) and Golgi. Upon treatment with phorbol myristate acetate (PMA), PKC alpha translocated from the cytosolic fraction to the membrane fraction to which PLD1 also localized. GFP-PLD1 was found in the plasma membrane as well as a in a perinuclear compartment consistent with ER and Golgi and in other dispersed vesicular structures in the cytoplasm. However, most of GFP-PKC alpha was translocated from the cytosol to the plasma membrane after treatment with PMA. From these results, we concluded that the plasma membrane is the major site of PLD1 activation by PKC alpha in 3Y1 cells.

Gaegurin 4, a peptide antibiotic of frog skin, forms voltage-dependent channels in planar lipid bilayers

Gaegurin 4 (GGN4) is a cationic peptide of 37 amino acids (MW 3748) isolated from the skin of Rana rugosa. It has shown a broad spectrum antimicrobial activity in vitro against Gram-negative and -positive bacteria, fungi and protozoa. To understand its mechanism of antimicrobial action, we examined the effect of GGN4 on the membrane conductance and the electrical properties of GGN4-induced pores in planar lipid bilayers under voltage clamp. Natural and synthetic GGN4 (0.01-1 microg/mL) increased the membrane conductance in a concentration-dependent manner, but GGN4 (1-23), an N-terminal fragment of the peptide with little antimicrobial activity, failed to increase the conductance. At symmetrical 100 mM KCI, unitary conductances of about 120 pS were frequently observed. Their current-voltage relations were linear and open state probabilities were close to 1, but longer closing events were seen more frequently at negative voltages. In addition, GGN4-induced pores were selective for cation over anion, the permeability ratio of K+ to Cl- being 6: 1 in neutral and 7: 1 in acidic lipid bilayers. In conclusion, our results indicate that GGN4 forms voltage-dependent and cation-selective pores in planar lipid bilayers. The ionophoric property of GGN4 is likely to contribute to its antimicrobial activity.

Optical responses evoked by single-pulse stimulation to the dorsal root in the rat spinal dorsal horn in slice

Neuronal excitation evoked after dorsal-root (DR) stimulation in the spinal dorsal horn (DH) of rats was visualized with a high-resolution optical-imaging method, and the propagation mechanism was studied. Transverse slices of the spinal cord were obtained from 2-4 week-old rats and stained with the voltage-sensitive dye RH-482. Single-pulse stimulation to the primary-afferent A fibers in the DR attached to the slice evoked a weak, brief (<10 ms) excitatory optical response in the laminae I and III-V. When the stimulus intensity and duration were increased to activate both A and C fibers, an additional, much greater, and longer-lasting (>100 ms) excitatory response was generated in the laminae I-III, most intensely in the lamina II. A treatment with excitatory amino acid (EAA) antagonists, dl-2-amino-5-phosphonovaleric acid and 6-cyano-7-nitroquinoxaline-2, 3-dione, significantly reduced the amplitude and duration of the response in the lamina II. The optical response in the antagonists-containing solution was quite similar to that recorded in a Ca2+-free solution that blocked afferent synaptic transmission. The late component (>10 ms) was, however, slightly greater than that in the Ca2+-free solution. Treatment with the ATP-receptor antagonist, suramin, had a minimal effect on the response in the presence of EAA antagonists. These results suggested that the propagation of the DR-stimulus-elicited excitation was contributed largely by EAA receptors, but also by other receptors to a much lesser extent.

MK-801, a non-competitive NMDA receptor antagonist, prevents postischemic decrease of inositol 1,4,5-trisphosphate receptor mRNA expression in mongolian gerbil brain

Changes of inositol 1,4,5-trisphosphate receptor (IP3R) mRNA expression after transient brain ischemia and the effect of MK-801, a non-competitive N-methyl-D-aspartic acid (NMDA) receptor antagonist, on the IP3R mRNA expression was studied in mongolian gerbil brain by in situ hybridization. Transient ischemia was induced by ligating left common carotid artery for 10 min, and the animals were allowed recovery from 15 min to 24 h. MK-801 was introduced intraperitoneally 30 min before ischemia. IP3R mRNA expression was decreased in dentate gyrus and hippocampus from 90 min until 24 h after ischemia. MK-801 pretreatment prevented the change of IP3R mRNA expression after ischemia. These results suggest that IP3R mRNA expression in ischemia may be related with NMDA receptor.

MKP-1 induced in rat brain after electroconvulsive shock is independent of regulation of 42- and 44-kDa MAPK activity

Electroconvulsive shock (ECS) activates MAPKs in rat brain and also induces immediate early genes. We investigated whether ECS induces MKP-1, a specific MAPK phosphatase and an immediate early gene, for feedback regulation of MAPK activity. ECS induced MKP-1 in the cortex, but MAPK activity returned to its basal level before MKP-1 protein increased, within 10 min of ECS. MKP-1 protein amount peaked 1 hr after ECS. MKP-1 induced did not lower the basal level of MAPK activity or attenuate MAPK activation by second ECS. MAPK activation in cerebellum was very weak, but the MKP-1 induction was faster and more prominent than in the cortex. These results suggest that ECS induces MKP-1 in various rat brain regions, however, the induction may not be related to the activation of MAPK and the MKP-1 induced may be independent of the regulation of MAPK activity after ECS.