p21 promotes ceramide-induced apoptosis and antagonizes the antideath effect of Bcl-2 in human hepatocarcinoma cells

p21, a potent cyclin-dependent kinase inhibitor, has been known to induce cell cycle arrest in response to DNA-damaging agents. Although p21 has been reported to play an important role in the regulation of apoptosis, the postulated role for p21 in apoptosis is still controversial. Previously, we reported that p21 was induced in a p53-independent manner during ceramide-induced apoptosis in human hepatocarcinoma cell lines. In the present study, we investigated the precise role of p21 in ceramide-induced apoptosis in human hepatocarcinoma cells by using a tetracycline-inducible expression system. Overexpression of p21 by itself did not induce apoptosis in p53-deficient Hep3B cells. However, Hep3B/p21 cells were more sensitive to ceramide-induced apoptosis. In these cells, p21 overexpression did not result in G1 arrest. The expression level of Bax was increased in Hep3B/p21 cells treated with ceramide and its expression was more accelerated under the p21-overexpressed condition compared to that of the p21-repressed condition. Overexpression of Bax induced apoptosis in Hep3B cells. On the other hand, the levels of p21 and Bax protein were increased by ceramide in another hepatocarcinoma cell line, SK-Hep-1, while the Bcl-2 protein level was not changed. Overexpression of Bcl-2 not only suppressed apoptosis but also completely prevented induction of p21 and Bax caused by ceramide in SK-Hep-1 cells. Furthermore, overexpression of p21 antagonized the death-protective function of Bcl-2 and upregulated expression of Bax protein. These results suggest that p21 promotes ceramide-induced apoptosis by enhancing the expression of Bax, thereby modulating the molecular ratio of Bcl-2:Bax in human hepatocarcinoma cells.

Diffuse and focal adenomyosis: MR imaging findings

Adenomyosis is a common gynecologic disorder that affects women during their menstrual life. Preoperative magnetic resonance (MR) images obtained in 45 patients with pathologically proved adenomyosis who underwent hysterectomy were retrospectively reviewed. Diffuse adenomyosis was seen in 30 cases (66.7%) and focal adenomyosis in 15 cases (33.3%). On T2-weighted MR images, diffuse adenomyosis usually manifested as diffuse thickening of the endometrial-myometrial junctional zone (7-37 mm; mean, 16 mm) with homogeneous low signal intensity. T2-weighted MR images were superior to contrast material-enhanced T1-weighted images in the evaluation of junctional zone thickening. High-signal-intensity foci were observed on T2-weighted images only in nine cases and on both T1- and T2-weighted images in three cases. Focal adenomyosis manifested on both T2-weighted and contrast-enhanced T1-weighted MR images as a localized, low-signal-intensity round or oval mass with a diameter of 2-7 cm (mean, 3.8 cm). All but one of the focal lesions had ill-defined margins. High-signal-intensity foci were noted in all cases of focal adenomyosis, either on T2-weighted images only (four cases) or on both T1- and T2-weighted images (11 cases). MR imaging is useful in diagnosing adenomyosis, differentiating adenomyosis from uterine myoma, and planning appropriate treatment.

Cemento-ossifying fibroma presenting as a mass of the parapharyngeal and masticator space

We report a case of cemento-ossifying fibroma that presented as a large extraosseous mass in the masticator and parapharyngeal space. CT scanning and MR imaging showed a large extraosseous mass with central conglomerated, well-matured ossified nodules and fatty marrow. The central matured ossified nodules were of low density on CT scans and high signal intensity on T1- and T2-weighted MR images. Multiplanar reformatted CT scans revealed the origin of the mass to be at the extraction site of the right lower second molar tooth.

Structure of a fructose-1,6-bis(phosphate) aldolase liganded to its natural substrate in a cleavage-defective mutant at 2.3 A(,)

Class I fructose-1,6-bis(phosphate) aldolase is a glycolytic enzyme that catalyzes the cleavage of fructose 1,6-bis(phosphate) through a covalent Schiff base intermediate. Although the atomic structure of this enzyme is known, assigning catalytic roles to the various enzymic active-site residues has been hampered by the lack of a structure for the enzyme-substrate complex. A mutant aldolase, K146A, is unable to cleave the C3-C4 bond of the hexose while retaining the ability to form the covalent intermediate, although at a greatly diminished rate. The structure of rabbit muscle K146A-aldolase A, in complex with its native substrate, fructose 1,6-bis(phosphate), is determined to 2.3 A resolution by molecular replacement. The density at the hexose binding site differs between subunits of the tetramer, in that two sites show greater occupancy relative to the other two. The hexose is bound in its linear, open conformation, but not covalently linked to the Schiff base-forming Lys-229. Therefore, this structure most likely represents the bound complex of hexose just after hemiketal hydrolysis and prior to Schiff base formation. The C1-phosphate binding site involves the three backbone nitrogens of Ser-271, Gly-272, and Gly-302, and the epsilon-amino group of Lys-229. This is the same binding site previously found for the analogous phosphate of the product DHAP. The C6-phosphate binding site involves three basic side chains, Arg-303, Arg-42, and Lys-41. The residues closest to Lys-229 were relatively unchanged in position when compared to the unbound wild-type structure. The major differences between the bound and unbound enzyme structures were observed in the positions of Lys-107, Arg-303, and Arg-42, with the greatest difference in the change in conformation of Arg-303. Site-directed mutagenesis was performed on those residues with different conformations in bound versus unbound enzyme. The kinetic constants of these mutant enzymes with the substrates fructose 1, 6-bis(phosphate) and fructose 1-phosphate are consistent with their ligand interactions as revealed by the structure reported here, including differing effects on k(cat) and K(m) between the two substrates depending on whether the mutations affect C6-phosphate binding. In the unbound state, Arg-303 forms a salt bridge with Glu-34, and in the liganded structure it interacts closely with the substrate C6-phosphate. The position of the sugar in the binding site would require a large movement prior to achieving the proper position for covalent catalysis with the Schiff base-forming Lys-229. The movement most likely involves a change in the location of the more loosely bound C6-phosphate. This result suggests that the substrate has one position in the Michaelis complex and another in the covalent complex. Such movement could trigger conformational changes in the carboxyl-terminal region, which has been implicated in substrate specificity.

The 2.1 A structure of a cysteine protease with proline specificity from ginger rhizome, Zingiber officinale

A cysteine protease from ginger rhizome (GP-II) cleaves peptides and proteins with proline at the P(2) position. The unusual specificity for proline makes GP-II an attractive tool for protein sequencing and identification of stably folded domains in proteins. The enzyme is a 221 amino acid glycoprotein possessing two N-linked oligosaccharide chains (8% glycosylated by weight) at Asn99 and Asn156. The availability of the sequence of these glycosyl chains afforded the opportunity to observe their structure and impact on protein conformation. The three-dimensional structure of GP-II has been determined by X-ray crystallography to a resolution of 2.1 A (overall R-factor = 0.214, free R = 0.248). The overall structure of GP-II is similar to that of the homologous cysteine proteases papain, actinidin, and glycyl endopeptidase, folding into two distinct domains of roughly equal size which are divided by a cleft. The observed N-linked glycosyl chains (half the total carbohydrate sequence) participate in both crystallographic and noncrystallographic contacts, tethering the proteins together via hydrogen bonds to the carbohydrate residues without intervening ordered water molecules. The putative S(2) binding pocket (the proline recognition site) was identified by superposition of the GP-II structure with structures of four previously determined papain-inhibitor complexes. The particular enzymic amino acids forming the S(2) pocket of GP-II (Trp, Met, and Ala) are similar to those found in the proline binding pockets of the unrelated enzymes alpha-lytic protease and cyclophilin. However, there is no conserved three-dimensional arrangement of these residues between the three enzymes (i.e., no proline binding motif). Thus, the particular amino acids found at S(2) are consistent with a binding pocket for a moiety with the steric characteristics and charge distribution of proline. Size exclusion is also a mechanism for selectivity compared to the S(2) binding pocket of papain. The S(2) binding pocket of GP-II greatly restricts the size of the side chain which could be bound because of the occurrence of a tryptophan in place of the corresponding tyrosine in papain. In light of the nature of the binding pocket, the specificity of GP-II for proline over other small nonpolar amino acids may be attributed to a direct effect of proline on the substrate peptide backbone conformation.

Chondroblastoma: MR characteristics with pathologic correlation

PURPOSE

The purpose of this study was to describe the MR findings of chondroblastoma with pathologic correlation.

METHOD

In 22 patients with pathologically proven chondroblastoma, MR signal characteristics were correlated with pathological findings.

RESULTS

On T2-weighted images, 12 (55%) lesions were hyperintense with hypointense areas in 9 lesions, whereas 10 (45%) were hypointense. Therefore, 19 of 22 (86%) lesions with pathologic correlation had hypointense areas entirely (n = 10) or partly (n = 9) on T2-weighted images. On gadolinium-enhanced images, 13 (59%) lesions showed lobular enhancement and 9 (41%) showed marginal and septal enhancement. Low signal intensity on T2-weighted MR images was most strongly associated with an abundance of immature chondroid matrix, hypercellularity of the chondroblasts, calcifications, and hemosiderin on histology.

CONCLUSION

Chondroblastoma was found to show hypointense portions on T2-weighted images. Signal intensity on T1- and T2-weighted MR images in chondroblastoma was dependent on the amounts of histopathological components.

Current status of peritoneal dialysis in Korea: efforts to achieve optimal outcome

Since its introduction in 1981, peritoneal dialysis (PD) has become firmly established as an effective mode of renal replacement therapy and serves an increasing patient population in Korea. The latest registry data indicate that about 3700 end-stage renal disease patients are maintained on chronic PD, representing 24.1% of the country's dialysis population. The majority (93.3%) of these patients are on continuous ambulatory peritoneal dialysis (CAPD) using the two-bag disconnect system, while only 3.3% are on automated PD. Under current renal reimbursement policies, most dialysis patients have to pay 20% of dialysis fees. Thus CAPD patients on 4 x 2-L daily exchanges pay about US$200 per month, not including medication and travel costs. Traditionally, most PD centers in Korea have used the "standard" prescription of 4 exchanges of 2 L of solution for most of their patients. A recent survey of 1467 patients who commenced CAPD in 1997 revealed that 84% of these patients were initially prescribed 4 x 2-L exchanges, while 12% were given a daily volume of 6 L. With this standard prescription, the percentages of Korean CAPD patients initially achieving the adequacy target of Kt/V urea > or = 2.0 and standardized creatinine clearance (SCCr) > or = 60 L/week/1.73 m2, were 74.4% and 82.1%, respectively. It is likely that, among current Korean CAPD patients, a much lower percentage will achieve the clearance targets compared to this initial outcome, but the precise data are not available. However, it is not clear whether the levels of small-solute clearance recommended for optimal PD outcomes, and proposed by the NKF-DOQI guidelines, will bring the expected benefits to Korean patients. Overall survival of Korean PD patients appears to be as good as, or even better than, that in most other countries. Recently, a single large PD center reported patient survival of 92.1%, 85.6%, 81.4%, and 67.6% at 1, 2, 3, and 5 years respectively. Other centers also reported similar outcomes. As in other countries, cardiovascular deaths predominate among Korean patients: death was due to cardiac causes in 29%, to vascular causes in 21%, and to infectious causes in 24%. Peritonitis is the most important barrier to prolonged use of CAPD in Korea, and more PD patients transfer to hemodialysis because of peritonitis than in other countries. To further reduce the morbidity and mortality of Korean PD patients, various control measures need to be implemented that can reduce or prevent peritonitis and other infectious complications. Also, to further improve long-term patient outcome, Korean nephrologists need to establish and practice optimal clearance targets in the chronic care of these patients.

Aldolase A Ins(1,4,5)P3-binding domains as determined by site-directed mutagenesis

We substituted neutral amino acids for some positively charged residues (R42, K107, K146, R148 and K229) that line the active site of aldolase A in an effort to determine binding sites for inositol 1, 4,5-trisphosphate. In addition, D33 (involved in carbon-carbon bond cleavage) was mutated. K229A and D33S aldolases showed almost no catalytic activity, but Ins(1,4,5)P(3) binding was similar to that determined with the use of wild-type aldolase A. R42A, K107A, K146R and R148A had markedly decreased affinities for Ins(1,4,5)P(3) binding, increased EC(50) values for Fru(1,6)P(2)-evoked release of bound Ins(1,4,5)P(3) and increased K(i) values for Ins(1,4, 5)P(3)-evoked inhibition of aldolase activity. K146Q (positive charge removal) had essentially no catalytic activity and could not bind Ins(1,4,5)P(3). Computer-simulated docking of Ins(1,4,5)P(3) in the aldolase A structure was consistent with electrostatic binding of Ins(1,4,5)P(3) to K107, K146, R148, R42, R303 and backbone nitrogens, as has been reported for Fru(1,6)P(2) binding. Results indicate that Ins(1,4,5)P(3) binding occurs at the active site and is not dependent on having a catalytically active enzyme; they also suggest that there is competition between Ins(1,4,5)P(3) and Fru(1, 6)P(2) for binding. Although Ins(1,4,5)P(3) binding to aldolase involved electrostatic interactions, the aldolase A Ins(1,4, 5)P(3)-binding domain did not show other similarities to pleckstrin homology domains or phosphotyrosine-binding domains known to bind Ins(1,4,5)P(3) in other proteins.

Comparison of two kinds of Biolog microplates (GN and ECO) in their ability to distinguish among aquatic microbial communities

We compared the abilities of Biolog's GN and ECO plates to distinguish among aerobic and heterotrophic bacterial communities in samples from six aquatic environments. The Biolog system is based on interpreting patterns of sole-carbon substrate utilization indicated by color development in a 96-well microtiter plate. Whether of fresh or saltwater origin, bacterial communities utilized > 95% of substrates in both types of plates. Samples from any one environment exhibited similar time courses of average well color development (AWCD) in both GN and ECO plates. Principal component analysis was performed on data sets resulting from combinations of algorithms (AWCD and curve-integration methods) and levels of color development (end-point and set-point approaches). In all cases, the two types of plates demonstrated an equal capacity to discriminate among the heterotrophic expressions of the six microbial communities. Substantial deviation from an anticipated 1:1 correspondence occurred when color development of 25 substrates common to both types of plates was compared. The discrepancies likely are related to the different formulations of low-nutrient media in GN and ECO plates.

MRI of tuberculous pyomyositis

PURPOSE

The purpose of this article is to describe the findings of MRI in tuberculous pyomyositis (PM).

METHOD

The MR images of four proven cases of tuberculous PM were retrospectively reviewed and analyzed with clinical and laboratory findings. The location, signal intensity on T1- and T2-weighted spin echo images, presence of abscess, signal intensity of peripheral rim, patterns of contrast enhancement, and associated findings were evaluated.

RESULTS

On MR images, all cases demonstrated low signal intensity on T1-weighted images and high signal intensity on T2-weighted images in a single muscle. Abscess was seen in all cases. Peripheral rim showed subtle hyperintensity on T1-weighted images and hypointensity on T2-weighted images. After gadolinium infusion, peripheral rim enhancement was observed in all cases. Cellulitis was associated in one case. The patients clinically presented with a palpable mass of long duration.

CONCLUSION

Tuberculous PM shows characteristic findings of a well demarcated abscess with rim enhancement at MRI and can be distinguished from other soft tissue masses.

Treatment delay and reliance on private physicians among patients with sexually transmitted diseases in China

We examined health-care seeking practices among patients with sexually transmitted diseases (STDs) in south China. In 1995, we recruited a consecutive sample of 939 STD patients attending the STD clinics of the Municipal STD Control Centers of Guangzhou and Shenzhen, 'special economic zones' near Hong Kong. Attending physicians interviewed patients face-to-face using a standard survey questionnaire. Twenty-seven per cent of all subjects had sought treatment elsewhere for their presenting complaints, before visiting a study clinic. The main sources of prior treatment were private physicians followed by public clinics and drugstores. Women were more likely than men to delay in presenting their current symptoms to a study clinic (32% vs 25%, P=0.046). Factors associated with treatment delay differed by gender. Among men, seeking prior treatment from private physicians (OR=3.31; 95% CI=1.70, 6.43), having no urethral discharge (OR=4.00; 95% CI=2.33, 6.85), having engaged in sex trade (OR=1.64; 95% CI=1.03, 2.63), or being a resident in Shenzhen (OR=1.80; 95% CI=1.12, 2.89) were more likely to delay seeking treatment. Among women, only living in Shenzhen (OR=2.86; 95% CI=1.56, 5.25) was associated with treatment delay. Promotion of appropriate health-seeking behaviours and better management of STDs must be a top priority to slow a rapid spread of STD/HIV in China. Health education, improvement of STD care in the public and private sectors, and regulations of unauthorized private physicians, may help with STD control and HIV prevention.

CT features of systemic lupus erythematosus in patients with acute abdominal pain: emphasis on ischemic bowel disease

PURPOSE

To evaluate the computed tomographic (CT) features of systemic lupus erythematosus (SLE) in patients with acute abdominal pain. Special emphasis was placed on the analysis of ischemic bowel disease.

MATERIALS AND METHODS

The authors retrospectively reviewed the images from 39 abdominal CT examinations performed in 33 patients with SLE and acute abdominal pain. Images were evaluated for bowel wall changes, mesenteric changes, fluid collection, retroperitoneal lymphadenopathy, peritoneal enhancement, and hepatomegaly as well as for changes in other abdominal organs. Ischemic bowel disease was diagnosed if at least three of the following signs were seen: bowel wall thickening, target sign, dilatation of intestinal segments, engorgement of mesenteric vessels, and increased attenuation of mesenteric fat.

RESULTS

Thirty-one (79%) of the 39 examinations had CT findings diagnostic of ischemic bowel disease, including symmetric bowel wall thickening (n = 29), target sign (n = 26), and mesenteric vascular engorgement and haziness (n = 31). In 24 cases, bowel wall thickening was multifocal, with variable length, and did not appear to be confined to a single vascular territory.

CONCLUSION

The most common CT finding in patients with SLE and acute abdominal pain is ischemic bowel disease. CT is useful for detecting the primary cause of gastrointestinal symptoms, planning treatment, and monitoring for infarction or perforation.

Risk factors influencing the decline of residual renal function in continuous ambulatory peritoneal dialysis patients

OBJECTIVE

To assess the nature of the decline in residual renal function (RRF) after the initiation of peritoneal dialysis, and to identify risk factors influencing the preservation of RRF.

DESIGN

A retrospective single-center study.

SETTING

Tertiary medical center.

PATIENTS

Eighty patients who were clinically stable and had been on continuous ambulatory peritoneal dialysis (CAPD) for a minimum of 6 months.

MAIN OUTCOME MEASURES

All subjects had at least three measurements of RRF, which was calculated as the average of creatinine clearance (Ccr) and urea clearance from a 24-hour urine collection. All measurements of RRF were plotted on a logarithmic scale and a linear scale against the duration of CAPD. Covariables used in the correlation analyses were age, sex, the presence of diabetes mellitus, mean blood pressure, mean diastolic blood pressure, hematocrit and Ccr at the start of peritoneal dialysis, peritoneal membrane transport characteristics by peritoneal equilibration test (PET), and the rate of peritonitis.

RESULTS

A significant correlation was found between CAPD duration and RRF decline represented on a logarithmic scale with a correlation coefficient (r) of 0.355 (p < 0.001). In contrast, on a linear scale, the correlation coefficient was only 0.273 (p < 0.01). By linear multiple regression analysis, the only independent risk factor for the decline of RRF was the rate of peritonitis (r = -0.446, p < 0.001).

CONCLUSION

These results suggest that RRF declines exponentially rather than linearly with time, and that the rate of peritonitis is an independent risk factor for the decline of RRF in CAPD patients.

The validity of random urine specimen albumin measurement as a screening test for diabetic nephropathy

To assess the validity of urine albumin concentration (UAC) and the urine albumin:creatine ratio (UACR) in a random urine specimen (RUS) for screening diabetic nephropathy in Korea, a total of 105 ambulatory diabetes mellitus patients (male:female, 52:53), ages 40-75 years (median 59 years) collected 105 RUSs after completing a timed 24 hour urine collection. Albumin was measured by immunonephelometry. According to the timed urinary albumin excretion rate (UAER) measured in the 24 hour collection (criterion standard), samples were classified normoalbuminuric (UAER < 20 micrograms/min; n = 50), microalbuminuric (UAER 20-200 micrograms/min; n = 30), and macroalbuminuric (UAER > 200 micrograms/min; n = 25). The receiver operating characteristics (ROC) curve of UAC and UACR in a RUS for screening of microalbuminuria (normo- and microalbuminuric samples; n = 80) and macroalbuminuria (micro- and macroalbuminuric samples; n = 55) were plotted. Pearson's coefficients of correlation of 24 hour UAER vs. UAC and UACR were 0.81 and 0.75, respectively (P < 0.001). The point of intersection with a 100%-to-100% diagonal for microalbuminuria were as follows: 31.0 mg/l for UAC and 32.5 mg/g for UACR; for macroalbuminuria 181 mg/l for UAC and 287.3 mg/g for UACR. The sensitivity and specificity of the cut-off points for microalbuminuria were 77% and 82% for UAC and 77% and 92% for UACR. The sensitivity and specificity of the cut-off points for macroalbuminuria were 84% and 90% for UAC and 88% and 90% for UACR. In present study, no difference was observed when comparing the performance of UAC and UACR based on a statistical comparison by McNemar test. The repeated measurements of UAC and UACR in the same individual were statistically similar and were correlated with each other. Based on these results, albumin measurements (UAC and UACR) in a RUS were considered as a valid test for screening diabetic nephropathy.

Results of kidney transplantation from 1979 to 1997 at Yonsei University

1. Long-term graft survival markedly improved after the introduction of CsA as the main immunosuppressant in living-donor kidney transplantation at our institution. 2. HLA-identical LRD kidney transplantation provided the best long-term graft survival rate, probably due to a decreased incidence of graft loss from rejection. 3. We could achieve good long-term graft survival in LURD kidney transplantation compared with that of HLA-haploidentical LRD kidney transplantation. 4. Because of the striking discrepancy between organ donation and the increasing demand for transplantation, distant relative donors and LURDs, including swap donors, should be considered as an alternative way to increase the number of available donors when accompanied by a careful evaluation process.

Membranoproliferative glomerulonephritis associated with HCV infection in native kidneys and renal allograft

Hepatitis C viral infection occurs relatively low in Korea compared to hepatitis B. However, it progresses into chronic hepatitis and cirrhosis more frequently than HBV. It may be associated with cryoglobulinemia and glomerulonephritis, both in native and transplanted kidneys. We report three cases of membrano-proliferative glomerulonephritis type I in anti-HCV positive, but cryoglobulin-negative patients, presenting massive proteinuria, two in native kidneys and one in an allograft. HCV-RNA was positive in sera of two patients. Two were cirrhotic and ALT was mildly elevated in two. In addition to the characteristic membranoproliferative feature, two native kidneys overlapped with features of diabetic nephropathy. Immunofluorescence demonstrated mainly IgM and C3 deposits along the peripheral capillary walls. Subendothelial electron dense deposits were present in the glomeruli of all three cases with subepithelial and intramembranous deposits in two. HCV-RNA was associated not only with a greater amount of immune deposits but also with subepithelial and intramembranous deposits, indicating the role of active infection.

Nonossifying fibroma: characteristics at MR imaging with pathologic correlation

PURPOSE

To correlate the findings of nonossifying fibroma at magnetic resonance (MR) imaging with those at pathologic examination.

MATERIALS AND METHODS

In 19 patients (age range, 8-25 years; mean age, 14 years) with pathologically proved nonossifying fibroma, MR images were analyzed for signal intensity and patterns of contrast enhancement. Findings at MR imaging and biopsy were correlated.

RESULTS

On T1-weighted images, all nonossifying fibromas had low signal intensity compared with that of skeletal muscle. On T2-weighted images, 15 lesions (79%) were hypointense and four (21%) were hyperintense. On gadolinium-enhanced images, intense contrast enhancement was seen throughout 15 lesions (heterogeneous pattern in 12 and homogeneous in three) and in the margins and septa in four. Extensive hypercellular fibrous tissue and hemosiderin seen at pathologic examination were depicted with low signal intensity on T2-weighted MR images.

CONCLUSION

The distinguishing features of nonossifying fibroma included hypointensity and septation on T2-weighted images. Signal intensity on T1- and T2-weighted MR images and the patterns of contrast enhancement were dependent on the amounts of hypercellular fibrous tissue, hemosiderin, hemorrhage, collagen, foamy histiocytes, and bone trabeculae.

Naphthoquinone analogs as inactivators of cdc25 phosphatase

cdc25A and cdc25B were significantly overexpressed in certain types of cancers, and they represent potential therapeutic targets for anticancer drug. In this study, naphthoquinone analogs as cdc25A phosphatase inactivators were investigated.

The plica syndrome: diagnostic value of MRI with arthroscopic correlation

PURPOSE

Our goal was to evaluate the diagnostic value of MRI in plica syndrome.

METHOD

MR images of a patient group (n = 55) with arthroscopically confirmed pathologic mediopatellar plicae were retrospectively analyzed and compared with those of a control group (n = 100). We obtained axial multiplanar gradient-recalled (MPGR), axial T1-weighted, and sagittal T2-weighted MR images. MR images were assessed for the width and length of all medial plicae.

RESULTS

In the diagnosis of plica syndrome, sensitivity and specificity were 73 and 78% on axial MPGR images, 71 and 83% on sagittal T2-weighted images, and 95 and 72% on combination of both images, respectively. The incidence of pathologic medial plica increased with a criterion of extension beyond the medial end of the patella on axial MPGR images.

CONCLUSION

MRI is a useful screening method in the diagnosis of plica syndrome.

Effects of niacin deficiency on the levels of soluble proteins and enzyme activities in various tissues of Japanese quail

The effects of niacin deficiency on the levels of soluble proteins and enzyme activities of Japanese quail have been investigated. SDS-polyacrylamide gel electrophoresis revealed that in the pectoral muscle the soluble proteins with molecular masses corresponding to 181, 128, 93, 76, 72, 62, 56, 43, 41, 28 and 20 kDa were present in lower amounts but those of 60, 50 and 37 kDa were present in higher amounts. In the heart the soluble proteins with a molecular mass of 181 kDa were present in lower amounts and in the brain those of 43 kDa were present in lower amounts but those of 221 kDa were present in higher amounts. In the intestine the soluble proteins with molecular masses corresponding to 181, 102, 83, 74, 72, 44 and 40 kDa were present in lower amounts but those of 41 kDa and 18 kDa were present in higher amounts. There was a marked reduction in the level of NAD and NADPH in the pectoral muscle of niacin deficient quail but not in other tissues. The specific activity of glyceraldehyde-3-phosphate dehydrogenase decreased markedly both in the liver and pectoral muscle of niacin deficient quail whereas that of 6-phosphogluconate dehydrogenase and malic enzyme decreased markedly in the liver or pectoral muscle, respectively. In contrast, the specific activity of acetylcholinesterase and carboxypeptidase increased markedly in the liver or the pectoral muscle, respectively. The results suggest that a severe niacin deficiency exerted specific effects on levels of some soluble proteins particularly in the pectoral muscle and intestine and on activities of certain enzymes in the liver and the pectoral muscle.

Induction of p21 during ceramide-mediated apoptosis in human hepatocarcinoma cells

Ceramide acts as a mediator of programmed cell death in various cell types, but its molecular mechanisms linked to the cell cycle are poorly understood. In this study, we investigated the expression of the p21 gene and its relationship to apoptosis induced by ceramide. In SK-HEP-1 cells, the addition of C6-ceramide resulted in a dose- and time-dependent growth suppression and DNA fragmentation characteristics of apoptosis. p21 protein was induced during that process, while the protein level of p53, known as a transcriptional activator of p21, was not elevated under the same condition. This apoptotic cell death with p21 induction was also observed in the Hep 3B cells lacking functional p53 after exposure to C6-ceramide. These findings suggest that ceramide-induced apoptosis is associated with the upregulation of p21 mRNA and protein in a p53-independent pathway.

Clinical results of 24 pituitary macroadenomas with linac-based stereotactic radiosurgery

PURPOSE

To determine the impact of stereotactic radiosurgery (SRS) on the clinical course, hormonal status, and follow-up CT/MRI scan of pituitary macroadenomas.

METHODS AND MATERIALS

From July 1988 to March 1996, 24 pituitary macroadenomas had been treated using 6 MV linear accelerator based SRS. They consisted of 11 (45.8%) prolactinomas, 2 (8.3%) growth hormone (GH)-secreting tumors, 1 (4.2%) Cushing's disease, 8 (33.3%) nonsecreting (nonfunctioning: NF) tumors, and 2 (8.3%) mixed prolactin-growth hormone (PRL-GH)-secreting tumors (M:F = 12:12; aged 21-61 years). Postoperative irradiation was performed in all cases except for the instance of Cushing's disease. The prescribed dose to tumor center varied from 10 to 27 Gy (mean 21.1 Gy) using a collimator size of 0.5 to 2.5 cm. The follow-up duration ranged from 13 to 89 months (mean 49.2 months). Results from these patients were compared to our results using conventional radiation.

RESULTS

Visual acuity and field defect were improved or became normal in 19 (79.2%) cases. Four (16.7%) remained unchanged after the treatment. One (4.1%) progressed 6 years after SRS and subsequently had repeat surgery with conventional boost irradiation. Of the 13 (46.4%) prolactinomas, including two mixed PRL-GH secreting tumors, 11 (84.1%) revealed normal hormonal levels within 1 year after SRS. In contrast, it took 2 years to become normal after conventional radiation therapy. In four GH-secreting tumors including two mixed PRL-GH secreting tumors, SRS and conventional methods showed similar responses. On follow-up imagings of the 21 patients, the mass was completely resolved in 4 (16.7%), including 3 PRLs and one NF, decreased in 11 (45.8%), and unchanged in 5 (16.7%) with central necrosis or cysts. One (4.2%) progressed and was reoperated 6 years after treatment. The complications related to SRS were comparable to those from conventional method.

CONCLUSION

Radiosurgery can be used effectively in patients with pituitary adenoma. In this study, a more rapid hormonal and clinical response was achieved with radiosurgery than with conventional pituitary irradiation treatment.

Serum C-reactive protein: a predictor of mortality in continuous ambulatory peritoneal dialysis patients

OBJECTIVE

To evaluate the predictive value of a single baseline serum C-reactive protein (sCRP) as a marker of mortality in continuous ambulatory peritoneal dialysis (CAPD) patients.

DESIGN

A review of prospectively collected data in a 2-year follow-up study.

SETTING

Tertiary medical center.

PATIENTS

The study included 106 patients who were stable and had been on CAPD for a minimum of 3 months.

MAIN OUTCOME MEASURES

Patient survival rate was the main outcome measure of this study. Other outcome measures were technique survival rate, peritonitis rate, and hospitalized days. Covariables used in the survival analysis were age, sex, the presence of cardiovascular disease or diabetes mellitus, sCRP, serum albumin, hematocrit, cholesterol, HDL-cholesterol, malnutrition by subjective global assessment (SGA), weekly Kt/V urea, and weekly standardized creatinine clearance (SCCr).

RESULTS

The 2-year patient survival rate was significantly lower in the increased sCRP group than in the normal sCRP group (66.7% vs 94.1%, p = 0.001), although there was no significant difference in technique failure, peritonitis rate, and hospitalized days between the two groups. By Cox proportional hazards analysis, independent predictors of mortality were: cardiovascular disease (relative risk, RR = 8.96, p < 0.005); increased sCRP level (RR = 1.19, p < 0.05); and high hematocrit (RR = 1.18, p < 0.05).

CONCLUSION

Serum CRP at enrollment is an independent predictor of 2-year patient survival in CAPD patients.

HIV prevention among Asian and Pacific Islander American men who have sex with men: a critical review of theoretical models and directions for future research

Nationally, the incidence of AIDS is increasing at a higher rate among Asian and Pacific Islander American men who have sex with men (API MSM) than among white MSM. Furthermore, current HIV prevention efforts are inadequate to slow the rapidly rising HIV epidemic in the gay API community, and little attention has been paid to the applicability of existing behavior change models to APIMSM. This paper reviews the five major models of health behavior change used in HIV prevention for the MSM population: the health belief model, theory of reasoned action, social learning theory, diffusion theory, and the AIDS risk reduction model. Although some of these models have been useful in designing risk reduction programs for API MSM, recent empirical data suggest that the models do not adequately address environmental influences affecting API MSM and limit our choices in prevention strategies to the level of the individual. We propose an ecological model for health promotion as a potentially useful theoretical framework, and suggest prevention strategies directed at the individual, the family, the general API community, and the mainstream gay community to reduce HIV risk among API MSM.