Screening method for detecting staphylococci with reduced susceptibility to teicoplanin

The incidence of infections caused by staphylococci with decreased susceptibility to teicoplanin (MIC>/=8 microg/ml) is increasing, but the disk diffusion test has difficulty detecting this low level of resistance. In addition, detection is complicated because of the heterogeneous phenotypes for teicoplanin. In this study, we evaluated an agar screening method to detect staphylococci with decreased susceptibility to teicoplanin or heterogeneous resistance. First, to investigate the inoculum density and teicoplanin concentration of screening agar, we used 10(5) and 10(6) CFU/ml and Mueller-Hinton agars supplemented with 6 and 8 microg of teicoplanin/ml to test 39 genetically distinct staphylococcal strains (15 strains with teicoplanin MICs>/=8 microg/ml and 24 strains with teicoplanin MICs</=4 microg/ml). On the basis of the results obtained, a final inoculum of 10(6) CFU/spot and a teicoplanin concentration of 8 microg/ml were selected. By this screening method, all strains having teicoplanin MICs>/=8 microg/ml or showing heteroresistance could be detected. These findings indicate that the method can be used as a reliable screening method for detecting staphylococci with reduced susceptibility to teicoplanin.

Assessment of coronary flow reserve with transthoracic Doppler echocardiography: comparison with intracoronary Doppler method

To evaluate the feasibility and usefulness of transthoracic Doppler echocardiography (TTDE) as a non-invasive method in recording distal anterior descending (LAD) coronary flow velocity, we compared coronary flow reserve (CFR) measured by TTDE with measurements by intracoronary Doppler wire (ICDW). Twenty-one patients without LAD stenosis were studied. ICDW performed at baseline and after intracoronary injection of 18 microg adenosine. TTDE was performed at baseline and after intravenous adenosine (140 microg/kgmin for 2 min). Adequate Doppler recordings of coronary flow velocities during systole were obtained in 14 of 21 study patients (67%) and during diastole in 17 (81%) patients. Baseline and hyperemic peak diastolic flow velocities measured by TTDE were significantly smaller than those obtained by ICDW (p<0.05). However, diminishing trends of diastolic and systolic velocity ratio after hyperemia were similarly observed in both methods. CFR obtained by TTDE (3.0+/-0.5), was higher than the value calculated by ICDW (2.5+/-0.4). There were significant correlations between the values obtained by the two methods (r=0.72, p<0.01). It is concluded that TTDE is a feasible method in measuring coronary flow velocity and appears to be a promising non-invasive method in evaluating CFR.

Glycation impairs high-density lipoprotein function

AIMS/HYPOTHESIS

To examine the effects of incubation of high-density lipoprotein (HDL) under hyperglycaemic conditions on several functions of HDL in vitro.

METHODS

Human HDL (5 mg protein) was incubated for 1 week at 37 degrees C in the presence or absence of 25 mmol/l glucose. Additional samples of human HDL were incubated in butylated hydroxytoluene to control for oxidation.

RESULTS

High-density lipoprotein incubated for 1 week in 25 mmol/l glucose had significant increases in the glycation product, fructoselysine and in the advanced glycation end product, N epsilon-(carboxymethyl)-lysine. High-density lipoprotein apolipoprotein AI and AII concentrations were not altered but glycated HDL had a 65% reduction in paraoxonase enzymatic activity. Glycated HDL did not inhibit monocyte adhesion to human aortic endothelial cells in response to oxidised low-density lipoprotein in vitro (43 +/- 4 monocytes bound vs 21 +/- 2 monocytes for control HDL, p < 0.0001). Hepatic lipase-mediated non-esterified fatty acid release from HDL lipids was enhanced in glycated HDL compared with control HDL (25 +/- 1 vs 16 +/- 1 nmol non-esterified fatty acid hydrolysed/min, respectively, p < 0.0001). Direct glycation of purified paraoxonase protein by incubation in 25 mmol/l glucose caused a 40% reduction in enzymatic activity. This glycated paraoxonase did not inhibit monocyte adhesion to human aortic endothelial cells in vitro (68 +/- 3 monocytes vs 49 +/- 2 monocytes bound for control paraoxonase, respectively, p < 0.001). We also measured a 40% reduction in paraoxonase activity in patients with Type II (non-insulin-dependent) diabetes mellitus and documented coronary artery disease compared with non-diabetic subjects, p < 0.0001.

CONCLUSIONS/INTERPRETATION

Alterations in function of HDL caused by exposure to hyperglycaemic conditions could contribute to the accelerated atherosclerosis observed in Type II diabetes.

Carotid artery stenting in patients with symptomatic coronary artery disease

Carotid artery stenting has been accepted as a potential alternative to carotid endarterectomy in patients with significant carotid artery stenosis. The objective of this study was to evaluate the feasibility, safety and long-term outcome of percutaneous stenting of carotid artery stenosis in patients with coexisting symptomatic coronary disease. Between May 1996 and May 1999, we performed carotid artery stenting at 48 lesions in 36 patients with carotid stenosis of 60% and symptomatic coronary artery stenosis. Twenty-one patients (58%) had neurologic symptoms. Carotid stenting was performed in 43 internal, 2 external and 3 common carotid lesions. We used Wallstent in 46 lesions, Palmaz stent in 2 lesions and Microstent II in 1 lesion. Staged or combined coronary intervention was performed in 18 patients (50%) and staged coronary artery bypass surgery was performed in 6 patients (17%). In the other 12 patients (33%), medical treatments were performed. Carotid stenting was successful in all lesions. Simultaneous bilateral carotid stenting was performed in 11 patients (31%). One major and 1 minor stroke developed during the procedure. There were no deaths during the procedures and within 30 days post-procedure. During the follow-up of 14 +/- 7 (3 to 40) months, there were no deaths or neurological events. On follow-up (6 +/- 1 months) angiography and/or duplex sonography of 44 eligible lesions in 32 patients, there were 2 cases of asymptomatic restenosis (4.5%) which developed in Palmaz stents implanted at the external carotid artery and the common carotid artery, respectively. In conclusion, carotid artery stenting in patients with coexistent carotid and coronary artery disease is feasible, safe and shows favorable follow-up outcomes.

Clinical characteristics of Peutz-Jeghers syndrome in Korean polyposis patients

Peutz-Jeghers syndrome is an autosomal dominant inherited disorder characterized by hamartomatous polyps in the small bowel and mucocutaneous pigmentation. Patients with Peutz-Jeghers syndrome often present as surgical emergencies with complications of the polyps, such as intussusception, bowel obstruction, and bleeding. Recently an increased risk of malignancies has also been reported. This study was initiated to determine the clinical features of Peutz-Jeghers syndrome in Korean patients, with special attention to the development of malignancies. Thirty patients with Peutz-Jeghers syndrome were investigated; their median age was 23.5 years, and symptoms appeared at a median age of 12.5 years. Family history was positive in one-half of cases, and mucocutaneous pigmentation was observed in almost all patients (93%). The jejunoileum was the most frequent site of the polyps, and there were generally 10-100 polyps. Multiple laparotomies were performed in a substantial portion of the patients, due mainly to polyp-induced bowel obstruction, and the surgical interventions were begun at a relatively young age (average 21.4 years). Four cases of small-bowel cancer and one case of breast cancer were detected in probands, at a relatively young age (mean 36 years). Cancers of the small bowel, stomach, colon, breast and cervix were diagnosed in the first relatives of the probands. Close follow-up from an early age should thus be performed in patients with Peutz-Jeghers syndrome as they are at high risk of surgical emergency and development of malignancy.

Characterization of a bioflocculant produced by Citrobacter sp. TKF04 from acetic and propionic acids

A bacterial strain, TKF04, capable of producing a bioflocculant from acetic and/or propionic acids was isolated from a biofilm formed in inside a kitchen drain. It was identified as a Citrobacter based on its morphological and physiological characteristics and the partial sequences of its 16S rRNA. TKF04 produced the bioflocculant during the logarithmic phase of growth, and the optimum temperature and pH for the bioflocculant production were 30 degrees C and 7.2-10.0, respectively. It could utilize some organic acids and sugars for its growth as the sole carbon sources when yeast extract was supplemented; however, only acetate and propionate were found to be good substrates for the bioflocculant production. The crude bioflocculant could be recovered from the supernatant of the culture broth by ethanol precipitation and dialysis against deionized water. It was found to be effective for flocculation of a kaolin suspension, when added at a final concentration of 1-10 mg/l, over a wide range of pHs (2-8) and temperatures (approximately 3-95 degrees C), while the co-presence of cations (Na+, K+, Ca2+, Mg2+, Fe2+, Al3+ or Fe3+) did not enhance the flocculating activity. It could efficiently flocculate a variety of inorganic and organic suspended particles, including kaolin, diatomite, bentonite, activated carbon, soil and activated sludge. It contained glucosamine as the major component, and the molecular weight was estimated to be between 232 and 440 kDa by gel filtration. The observation that the flocculating activity was completely lost following chitinase treatment and its analysis with a Fourier transform infrared spectrometer suggested that the bioflocculant is a biopolymer structurally-similar to chitin or chitosan.

Infantile fibromatosis in childhood: findings on MR imaging and pathologic correlation

AIM

The objective of this study was to analyse the MR imaging findings of infantile fibromatosis of childhood and to correlate them with histopathological features.

MATERIALS AND METHODS

Seven patients with histologically proven infantile fibromatosis were included in this study. The findings on MR images were retrospectively evaluated and then correlated with the pathological features. Findings on MR imaging evaluated included signal intensity, extent of hyperintense area on T2-weighted images, margins of the lesion, the degree and pattern of enhancement and the presence of fatty tissue. Pathological features evaluated included cellularity, collagenization, and myxoid change. A five point scale was used for the evaluation of the extent of hyperintense area on MR imaging, and each of pathological features.

RESULTS

On T1-weighted images, the lesions were iso-intense in two patients; iso- and hypointense in three; and iso-, hypo- and hyperintense in two. On T2-weighted images, iso-, hypo- and hyperintense areas were mixed in all patients, the hyperintense area being the largest portion of the lesion. The margins of the lesions were infiltrative in four patients (57%), smooth in two (29%) and mixed in one (14%). Enhancement was marked in five patients (72%) and diffuse in five (71%). Regardless of the hyperintense signal intensity on T2-weighted images, the grades of each pathologic feature were variable.

CONCLUSION

Infantile fibromatosis on MR imaging causes an enhancing mass, that is largely hyperintense on T2-weighted images. Areas of high signal intensity on T2-weighted images corresponded to variable grades of cellularity, collagenization, or myxoid change.

Macroamylasemia in a patient with acute appendicitis: a case report

Macroamylasemia is a condition of persistent, elevated serum amylase activity with no apparent clinical symptoms of a pancreatic disorder. In Korea, however, no such case has been reported to date. We report a case of a 17-year-old female diagnosed with macroamylasemia and acute appendicitis. One day earlier, she developed epigastric and right lower quadrant abdominal pain. She was characterized by high level of serum amylase, but normal lipase. Amylase isoenzyme analysis demonstrated increased fraction of salivary type and follow-up amylase level was persistently increased. Immunofixation disclosed the macroamylase binding with an immunoglobulin, consisting of IgA and kappa chain. The patient was treated by appendectomy, and the abdominal pain subsided.

Brachial plexopathy caused by subclavian artery aneurysm in Behçet's disease

As the cause of brachial plexopathy, an aneurysm of the subclavian artery is rare and mostly related to trauma. Early diagnosis and treatment is very important because the arterial aneurysm itself is life-threatening and nerve injury can be reversible in cases of early treatment. We report a patient with Behçet's disease having a right brachial plexopathy caused by a nontraumatic aneurysm of the right subclavian artery.

Human basophils express CD22 without expression of CD19

BACKGROUND

Even modern automatic cell counters cannot count basophils precisely. Therefore, we need a rapid, accurate, precise, and easy method for counting basophils.

METHODS

Using flow cytometry, basophils (CD22+/CD19-) and B cells (CD22+/CD19+) were counted. Within a large lymphocyte light scatter gate, % basophils (G%baso) and % B cells (G%B) were determined from the total count. Another method of analysis was to make two regions (R1 for basophils and R2 for B cells) and to determine in those the % basophils (R1%baso) and % B cells (R2%B) without gating. The flow cytometric basophil counts of the blood of 21 normal controls and 43 chronic myelogenous leukemia (CML) patients were compared with manual basophil count (Ma%baso) and basophil count by Coulter electronic cell counter (Hialeah, FL) (Auto%baso). CD22+/CD19- cells were sorted by a FACSCalibur (Becton Dickinson, San Jose, CA).

RESULTS

The G%baso of all samples was 4.66 +/- 5.35%, and R1%baso was 4.23 +/- 4.88%, and they were well-correlated (r = 0.996, P < 0.001). The G%B of all samples was 1.55 +/- 1.68%, and R2%B was 1.59 +/- 1.67%, and they were also well-correlated (r = 0.993, P < 0.001). Their correlation was better in normal controls than in CML. G%baso was well-correlated to Ma%baso (r = 0.827) and Auto%baso (r = 0.806), and R1%baso was well-correlated to Ma%baso (r = 0.831) but showed poor correlation to Auto%baso (r = 0.734). Auto%baso revealed the poorest correlation to Ma%baso (r = 0.692). The sorted CD22+/CD19- cells were all basophils (99.48 +/- 0.30%), and they revealed CD13, CD33, and dim CD45 expression, whereas CD3, CD14, CD16, and HLA-DR were not detected on them.

CONCLUSIONS

We discovered a specific marker combination to identify basophils (CD22+/CD19-), and we suggest that flow cytometric analysis using these markers is an easy, reliable, and accurate method of basophil counting.

DNA computing the Hamiltonian path problem

The directed Hamiltonian path (DHP) problem is one of the hard computational problems for which there is no practical algorithm on a conventional computer available. Many problems, including the traveling sales person problem and the longest path problem, can be translated into the DHP problem, which implies that an algorithm for DHP can also solve all the translated problems. To study the robustness of the laboratory protocol of the pioneering DNA computing for the DHP problem performed by Leonard Adleman (1994), we investigated how the graph size, multiplicity of the Hamiltonian paths, and the size of oligonucleotides that encode the vertices would affect the laboratory procedures. We applied Adleman's protocol with 18-mer oligonucleotide per node to a graph with 8 vertices and 14 edges containing two Hamiltonian paths (Adleman used 20-mer oligonucleotides for a graph with 7 nodes, 14 edges and one Hamiltonian path). We found that depending on the graph characteristics such as the number of short cycles, the oligonucleotide size, and the hybridization conditions that used to encode the graph, the protocol should be executed with different parameters from Adleman's.

Clinical analysis of 12 Korean Lambert-Eaton myasthenic syndrome (LEMS) patients

The Lambert-Eaton myasthenic syndrome (LEMS) heralds the occurrence of malignancy, especially small-cell lung cancer (SCLC), but it can also occur in the absence of cancer. Twelve patients were diagnosed as LEMS by clinical features and the classical electrophysiological triad, which includes a low amplitude of compound muscle action potentials (CMAP), decremental responses on low-rate stimulation, and incremental responses on high-rate stimulation on the repetitive nerve stimulation (RNS) test. There were 6 male and 6 female patients, ranging in age from 49 to 66 years. Malignancy(all were SCLC) was found in 7 patients. Males predominantly expressed the paraneoplastic form; whereas the primary autoimmune form was found only in women, who showed a good response to corticosteroid treatment. The neurological features were similar in both groups: proximal lower limb weakness, depressed muscle stretch reflexes, and dryness of mouth in nearly all patients. Bulbar dysfunction and limb paresthesia were a little more frequent in the paraneoplastic form. In RNS tests, the characteristic electrophysiological abnormalities were found in all patients and were more profound in the paraneoplastic form. We concluded that LEMS is commonly associated with malignancy, especially SCLC, but it should also be stressed that there are many female LEMS patients who do not harbor any malignancy at all, and that other treatment strategies such as immunotherapy should be considered for these patients.

Sinus histiocytosis (Rosai-Dorfman disease) clinically limited to the skin

Sinus histiocytosis with massive lymphadenopathy (SHML) is an idiopathic proliferation of unique histiocytes that have vesicular nuclei and voluminous pale cytoplasm, often with emperipolesis. Pure cutaneous involvement is very rare. We describe a patient with SHML limited to the skin whose lesion has spontaneously regressed. A 35-year-old Korean male visited the Department of Dermatology due to facial rash for 2 months. A 3 x 3.5 cm-sized well-demarcated dark erythematous nontender plaque was noted on the right cheek. Skin biopsy showed dense, nodular infiltrates of histiocytes with abundant cytoplasm and vesicular nuclei rimmed by lymphoplasma cell aggregates throughout the upper and mid-dermis. The histiocytes were immunohistochemically positive for S-100 protein and CD68, but negative for CD1a. Laboratory tests and a thorough physical examination revealed no abnormalities. These findings suggested that this was a case of SHML clinically limited to the skin. The skin lesion was initially resistant to steroid therapy, but began to regress 10 months after the onset without further treatment.

Intramuscular vascular malformations of an extremity: findings on MR imaging and pathologic correlation

OBJECTIVE

To analyze the findings of intramuscular vascular malformations of an extremity on MR imaging and to correlate these findings with histopathologic examination.

DESIGN AND PATIENTS

The findings on MR imaging and the medical records of 14 patients with an intramuscular vascular malformation of the extremity were retrospectively studied. All patients underwent surgical excision. Diagnoses were based on the results of pathologic examination. Findings on MR imaging were noted and correlated with the histopathologic findings.

RESULTS

Intramuscular vascular malformations of an extremity showed multi-septate, honeycomb, or mixed appearance on MR imaging. Multi-septate areas correlated with dilated and communicating vascular spaces with flattened endothelium. Honeycomb areas corresponded to vascular spaces with inconspicuous small lumina and thickened vascular walls. Areas of increased signal intensity on T2-weighted images were found in all intramuscular vascular malformations. Infiltrative margins were more commonly seen in intramuscular lymphaticovenous malformations. Adherence to neurovascular structures and orientation of the lesion along the long axis of the affected muscle were more commonly seen in intramuscular venous malformations.

CONCLUSIONS

Intramuscular vascular malformations showed either a multi-septate, honeycomb, or mixed appearance, reflecting the size of the vascular spaces and the thickness of the smooth muscles of the vessel walls. Prediction of the subtype of an intramuscular vascular malformation of an extremity on MR imaging seems to be difficult, although there are associated findings that may be helpful in the differential diagnosis of each subtype.

Phenotypic characteristics of Enterococcus faecium variants confirmed by intergenic ribosomal polymerase chain reaction and E. faecium polymerase chain reaction

Enterococcus faecium has recently emerged as a serious nosocomial pathogen. The emergence of multiple antimicrobial agent-resistant E. faecium has been remarkable; with its strains it is one of the most phenotypically heterogeneous of all enterococcal species. About 15% of enterococcal strains isolated from human clinical specimens were found to have atypical biochemical characteristics. In order to determine if these strains were E. faecium variants, intergenic ribosomal polymerase chain reaction (ITS-PCR) and E. faecium PCR (EfPCR) were performed in 45 atypical strains, and the two PCR results were used to analyze phenotypic characteristics of the strains. As many as 60% (27/45) of the atypical strains were identified as E. faecium. Thus, it is concluded that if an enterococcal strain shows positive reaction to arabinose, arginine, and ribose and negative reaction to methyl-alpha-D-glucopyranoside and pigment, it should be identified as E. faecium.

Congenital intraorbital optic nerve cyst. Case report

Congenital cystic lesions of the optic nerve are exceedingly rare; only one case is reported in the world literature. The authors describe a case of congenital simple glial cyst in the intraorbital portion of the optic nerve with a brief review of the literature and comment on its histogenesis. A 45-day-old male infant was admitted to the hospital because of progressive proptosis and hypotropia in the left eye, which had been present since birth. Magnetic resonance imaging of the left orbit revealed an ovoid, well-demarcated, homogeneous cystic mass in the intraconal retrobulbar area. The mass compressed the left eyeball with downward and lateral displacement. The wall of the cystic mass was very thin, and a needle puncture of the cyst released clear, colorless, watery fluid. The cystic wall was lined by loose astroglial nerve fibers with some scattered glial cells.

The efficacy of low-dose oral corticosteroids in the treatment of vitiligo patients

BACKGROUND

One of the most probable pathogeneses of vitiligo is autoimmunity. Systemic corticosteroids suppress immunity and may arrest the progression of vitiligo and lead to repigmentation. The clinical efficacy of low-dose oral corticosteroids was assessed to minimize the side-effects in actively spreading vitiligo patients.

METHODS

Eighty-one patients with vitiligo were evaluated. The patients took daily doses of oral prednisolone (0.3 mg/kg body weight) initially for 2 months; the dosage was then reduced to half of the initial dose for the third month and was halved again for the fourth and final month. The effects of treatment were evaluated using photographs of before and after the study. Side-effects were assessed at the first, second, third and fourth month of treatment.

RESULTS

Arrested progression of vitiligo and repigmentation were noted in 87.7% and 70.4% of patients respectively. Male sex, a patient age of 15 years or under, and a duration of disease of 2 years or less showed increased repigmentation with statistical significance. The side-effects of treatment were minimal and did not affect the course of treatment.

CONCLUSIONS

Low-dose oral corticosteroids are effective without serious side-effects in preventing the progression and inducing repigmentation of actively spreading vitiligo, which is difficult to treat with topical corticosteroids or photochemotherapy.

Serum levels of folic acid and vitamin B12 in Korean patients with vitiligo

The association of vitiligo and pernicious anemia has been previously documented. The low levels of folic acid and vitamin B12 were thought to be related to vitiligo. To date, there have been very few reports about the serum levels of folic acid and vitamin B12 in patients with vitiligo. Using radioimmunoassay, we measured the serum levels of folic acid and vitamin B12 in 100 Korean patients with vitiligo. The mean serum levels of folic acid and vitamin B12 were 6.31 +/- 2.82 ng/ml and 630.25 +/- 230.94 pg/ml, respectively, in patients with vitiligo. These levels showed no significant difference compared to the normal control group, suggesting that folic acid and vitamin B12 do not appear to play a role in the pathogenesis of vitiligo.

Influence of a replication enhancer on the hierarchy of origin efficiencies within a cluster of DNA replication origins

DNA replication origins in animal cells sometimes occur in clusters. Often one of the multiple origins within these clusters fires more frequently than the others. The reason for this hierarchy remains unknown. Similar origin clusters occur in the fission yeast, Schizosaccharomyces pombe. One such cluster is located near the ura4 gene on chromosome III and contains three origins: ars3002, ars3003, and ars3004. In their natural chromosomal context (ars3003 is about 2.5 kb upstream of ars3002 and ars3004 is adjacent to ars3002 on the downstream side) their initiation frequencies display a striking hierarchy: ars3002 >> ars3003 >> ars3004. Here, we describe experiments that reveal a 400 bp replication enhancer within ars3004, adjacent to ars3002. The enhancer is essential for ars3004 origin function in a plasmid, but even with the enhancer ars3004 is an inefficient origin. The enhancer is not essential for ars3002 plasmid origin activity, but dramatically stimulates this activity, converting ars3002 from an inefficient plasmid origin to a very efficient one. It also stimulates the plasmid origin activity of ars3001 and ars3003 at all tested positions and orientations on both sides of each autonomously replicating sequence (ARS) element. If ars3002 is redefined to include the enhancer, then the relative activities of the three ARS elements as single origins within separate plasmids or as origins when all three ARS elements are present in a single plasmid is the same as the chromosomal hierarchy. Thus, this replication enhancer defines the relative activities of the three origins in the ura4 origin region. Similar enhancers may affect relative activities in the origin clusters of animal cells.

The oxidative and nitrosative chemistry of the nitric oxide/superoxide reaction in the presence of bicarbonate

The primary product of the interaction between nitric oxide (NO) and superoxide () is peroxynitrite (ONOO-), which is capable of either oxidizing or nitrating various biological substrates. However, it has been shown that excess NO or can further react with ONOO- to form species which mediate nitrosation. Subsequently, the controlled equilibrium between nitrosative and oxidative chemistry is critically dependent on the flux of NO and. Since ONOO- reacts not only with NO and but also with CO2, the effects of bicarbonate () on the biphasic oxidation profile of dihydrorhodamine-123 (DHR) and on the nitrosation of both 2,3-diaminonaphthalene and reduced glutathione were examined. Nitric oxide and were formed with DEA/NO [NaEt2NN(O)NO] and xanthine oxidase, respectively. The presence of did not alter either the oxidation profile of DHR with varying radical concentrations or the affinity of DHR for the oxidative species. This suggests that the presence of CO2 does not affect the scavenging of ONOO- by either NO or. However, an increase in the rate of DHR oxidation by ONOO- in the presence of suggests that a CO2-ONOO- adduct does play a role in the interaction of NO or with a product derived from ONOO-. Further examination of the chemistry revealed that the intermediate that reacts with NO is neither ONOO- nor cis-HOONO. It was concluded that NO reacts with both trans-HOONO and a CO2 adduct of ONOO- to form nitrosating species which have similar oxidation chemistry and reactivity with and NO.

Evaluation of the viscoelastic properties of pharyngeal tissue

The viscoelastic properties of the human pharyngeal tissue in tension were evaluated, based on both an experimental protocol-consisting of cyclic load, tensile stress relaxation, and incremental step load tests-and a quasilinear viscoelastic theory. The physical properties of the pharyngeal tissue were evaluated to facilitate the biomechanical modeling of human pharynx. The methodology described has potentially significant clinical importance when one considers engineering a similar type of tissue having the same material properties in the future. Qualitatively, the characteristic features of viscoelastic properties of human pharyngeal tissue were experimentally obtained. Then, the reduced stress relaxation function and the elastic response of the pharyngeal tissue were derived from the experimental results specifically obtained from this tissue, by applying the quasilinear viscoelastic theory. The mathematical expression for analyzing nonlinear viscoelastic properties of human pharyngeal tissue is presented, as is the experimental protocol to evaluate the tissue properties. The characteristic features of the tissue need to be considered when attempting to engineer this tissue equivalent, and the data generated can be utilized to evaluate the function of tissue when it is engineered.

Targeting tumors with iodine-123 labeled deoxyuridine: distribution and DNA binding

5-lodo-2'-deoxyuridine (IUdR), a thymidine analog, is transported through cell membrane and is incorporated into newly synthesized DNA during the S phase of mitotic cells. In rapidly growing brain tumors such as glioma, radioiodinated IUdR may be an efficient diagnostic as well as therapeutic agent and may provide a means to determine the proliferative activity of the tumor. IUdR was labeled with 123I (t1/2 = 13.3 h, gamma = 159 KeV, 83%) and injected i.v. into nude mice bearing human colorectal carcinoma LS174T. At 3 and 20 h postinjection, tumor uptake was 2.6 +/- 0.9% and 0.5 +/- 0.2%, respectively, of the injected dose per gram of tissue. Radioactivity in other tissues also declined as a function of time, but much more rapidly, yielding tumor-to-blood ratios of 16.4 +/- 2.2 and tumor-to-muscle ratios of 22.2 +/- 7.7 at 20 h postinjection. Of the radioactivity in the tumor, 12.6 +/- 0.9% was bound to DNA at 3 h and 25.2 +/- 2% at 20 h postinjection. A high (7 +/- 1.1% i.d.) uptake in thyroid at 3 h postinjection indicated dehalogenation in vivo.

A case of pancytopenia secondary to low-dose pulse methotrexate therapy in a patient with rheumatoid arthritis and renal insufficiency

Most reports on serious MTX toxicity have focused on hepatic abnormalities, while other effects, including hematologic reactions, have not been emphasized. We experienced a case of pancytopenia secondary to MTX therapy in a patient with RA and renal insufficiency. A 67-year-old woman with a 12-year history of active seropositive RA that was a response to non-steroidal anti-inflammatory drugs, hydroxychloroquinine and intra-articular steroid injections, had been followed up and was diagnosed as early chronic renal failure in October, 1993. Recently, because of significant morning stiffness and polyarthralgia, the decision was made to institute MTX treatment. This was begun as a single oral dose of 5mg/week. After 2 doses, the patient was admitted to the hospital with general weakness. Laboratory tests showed a hemoglobin level of 7.9 g/dl, WBC count 1800/mm3 and platelet count of 64000/mm3. The serum creatinine level was 6.1 mEq/dl and the BUN level was 82 mEq/dl. Liver function test results were normal, but the serum albumin level was 2.7 g/dl. The patient subsequently developed fever and blood transfusions, granulocyte colony stimulating factor (G-CSF) and intravenous prophylactic antibiotic therapy were required. Her condition was improved. In summary, Low-dose MTX-related adverse hematologic side effects, including fatal pancytopenia, are rare but are a cause of increasing concern in patients with RA and renal insufficiency. Close monitoring of associated risk factors, particularly impaired renal function, should be mandatory for all patients who are receiving MTX therapy.

The effects of oxygen radicals on the activity of nitric oxide synthase and guanylate cyclase

Reactive oxygen species such as superoxides, hydrogen peroxide (H2O2) and hydroxyl radicals have been suggested to be involved in the catalytic action of nitric oxide synthase (NOS) to produce NO from L-arginine. An examination was conducted on the effects of oxygen radical scavengers and oxygen radical-generating systems on the activity of neuronal NOS and guanylate cyclase (GC) in rat brains and NOS from the activated murine macrophage cell line J774. Catalase and superoxide dismutase (SOD) showed no significant effects on NOS or GC activity. Nitroblue tetrazolium (NBT, known as a superoxide radical scavenger) and peroxidase (POD) inhibited NOS, but their inhibitory actions were removed by increasing the concentration of arginine or NADPH respectively, in the reaction mixture. NOS and NO-dependent GC were inactivated by ascorbate/FeSO4 (a metal-catalyzed oxidation system), 2'2'-azobis-amidinopropane (a peroxy radical producer), and xanthine/xanthine oxidase (a superoxide generating system). The effects of oxygen radicals or antioxidants on the two isoforms of NOS were almost similar. However, H2O2 activated GC in a dose-dependent manner from 100 microM to 1 mM without significant effects on NOS. H2O2-induced GC activation was blocked by catalase. These results suggested that oxygen radicals inhibited NOS and GC, but H2O2 could activate GC directly.

The free radical-generating function of a familial amyotrophic lateral sclerosis-associated D90A Cu,Zn-superoxide dismutase mutant

The free radical-generating functions of the D90A Cu,Zn-superoxide dismutase (SOD) associated with Swedish familial amyotrophic lateral sclerosis (FALS) patients are investigated. The results show that both the wild-type and mutant enzymes have identical dismutase activity, while the free radical-generating activity of the D90A mutant is enhanced relative to that of the wild-type enzyme. The studies suggest that the active channel of the D90A mutant is larger than that of the wild-type enzyme. A higher free radical-generating activity of the mutant enzyme led to the release of copper ions from the damaged protein. The generation of strand breaks in plasmid DNA was enhanced more effectively by the D90A mutant Cu,Zn-SOD than by the wild-type enzyme. The results suggest that the pathology of FALS may be attributed to oxidative damage caused by the gain-of-function of FALS Cu,Zn-SOD mutant.

Multiple orientation-dependent, synergistically interacting, similar domains in the ribosomal DNA replication origin of the fission yeast, Schizosaccharomyces pombe

Previous investigations have shown that the fission yeast, Schizosaccharomyces pombe, has DNA replication origins (500 to 1500 bp) that are larger than those in the budding yeast, Saccharomyces cerevisiae (100 to 150 bp). Deletion and linker substitution analyses of two fission yeast origins revealed that they contain multiple important regions with AT-rich asymmetric (abundant A residues in one strand and T residues in the complementary strand) sequence motifs. In this work we present the characterization of a third fission yeast replication origin, ars3001, which is relatively small ( approximately 570 bp) and responsible for replication of ribosomal DNA. Like previously studied fission yeast origins, ars3001 contains multiple important regions. The three most important of these regions resemble each other in several ways: each region is essential for origin function and is at least partially orientation dependent, each region contains similar clusters of A+T-rich asymmetric sequences, and the regions can partially substitute for each other. These observations suggest that ars3001 function requires synergistic interactions between domains binding similar proteins. It is likely that this requirement extends to other fission yeast origins, explaining why such origins are larger than those of budding yeast.

The genetics of vitiligo in Korean patients

BACKGROUND

Vitiligo is a common disorder whose exact cause is unknown, but genetic factors are thought to be involved. We analyzed 120 Korean proband families to clarify which genetic factors are involved in the pathogenesis of vitiligo in Korean patients.

METHODS

The genetics of vitiligo were analyzed in 120 Korean proband families out of 1030 vitiligo patients. Each family was analyzed through a proband afflicted with vitiligo.

RESULTS

In 51 (42.5%) of 120 proband families, at least one first-degree relative of the proband had vitiligo. The incidence of those affected among 1755 relatives (first-, second-, and third-degree) was found to be 8.0+/-0.6%. There was a statistically significant departure for segregation analysis which was inconsistent with inheritance as an autosomal or X-linked locus model. On the basis of our results, the inheritance pattern of vitiligo is more likely to tend toward the model of multifactorial inheritance. The threshold trait among first-degree relatives (7.2%) appeared to tend more toward the square root of the frequency in the general population (10%) than towards those of dominant (50%) or recessive (25%) models.

CONCLUSIONS

These results indicate that there are certain genetic factors involved in the etiology of vitiligo, and that vitiligo seems to have a polygenic nature.

Comparison of viscoelastic properties of the pharyngeal tissue: human and canine

The viscoelastic properties of the human and canine pharyngeal tissue in tension were evaluated, based on both an experimental protocol-consisting of cyclic load, tensile stress relaxation, and incremental step load tests-and the quasi-linear viscoelastic theory. The reduced stress relaxation function and the elastic response of the pharyngeal tissues were derived from the experimental results specifically obtained from those tissues. The characteristic features of viscoelastic property were obtained for both human and canine pharyngeal tissues by applying the quasi-linear viscoelastic theory and compared with each other. The material properties of the pharyngeal tissue were sought to facilitate the three-dimensional biomechanical model of the pharyngeal function by using the finite element method.

Vascular leiomyoma of an extremity: MR imaging-pathology correlation

OBJECTIVE

The objective of our study was to analyze MR images of vascular leiomyoma of the extremity and to compare these images with histopathologic findings to determine if a correlation exists.

CONCLUSION

T2-weighted MR images of vascular leiomyoma of an extremity showed a mass with mixed areas that were both hyper- and isointense to skeletal muscle and also revealed a hypointense rim; these images correlate with histopathologic findings of smooth muscle, vessels, fibrous tissue, an intravascular thrombus, and a fibrous capsule.

Comparative assessment of four different Tl-201 tumor uptake indices in the evaluation of brain tumors

The objective of this study was to determine which semi-quantitative thallium-201 brain tumor index correlated best with clinical outcome. Fifty-two patients had Tl-201 brain single-photon emission computer tomography (SPECT) performed for the evaluation of recurrent brain tumor. A semi-quantitative tumor index was calculated utilizing four currently available techniques: 1) the ratio of average counts of the region of interest (ROI) in the lesion area and its mirror image in normal brain tissue, 2) the ratio of maximum counts of the region of interest in the lesion area and its average counts in the mirror image, 3) the ratio of maximum counts of the region of interest in the lesion area and its mirror image and 4) the ratio of the average counts of the region of interest in the lesion area and the region of interest of the scalp. A two-tailed Student's t test was performed. The mean value plus one standard deviation was used to assess the sensitivity and specificity correlated with clinical follow-up evaluation, defined as inactive or active at the time of brain SPECT by the referring neurosurgeons. Results of correlation coefficient, P value, mean, standard deviation, sensitivity, and specificity of each index using cutoff values were obtained. For those patients with recurrence or residual malignant tumor after therapy, the maximum count ratio index correlated best with clinical outcome. It provided a sensitivity of 92% and specificity of 88% in differentiating active from inactive brain tumors.

Effect of superoxide and superoxide-generating systems on the prooxidant effect of iron in oil emulsion and raw turkey homogenates

Mechanisms of superoxide.O2--generating systems on the pro-oxidant effect of iron from various sources were studied. Reaction mixtures were prepared with distilled water, oil emulsion, or meat homogenates. Free ionic iron (ferrous and ferric), ferritin and hemoglobin (Hb) were used as iron sources, and KO2 and xanthine oxidase (XOD) systems were used to produce .O2-. Thiobarbituric acid reactive substances (TBARS) values and iron contents of the reaction mixtures were determined. Ferric iron and ferritin, in the presence or absence of superoxide-generating systems, had no catalytic effect on the oxidation of oil emulsion but became pro-oxidants when reducing agent (ascorbate) was present. Ferrous iron and Hb had strong catalytic effects on the oxidation of oil emulsion as shown by TBARS values. Superoxide and H2O2, generated from superoxide-generating systems, oxidized ferrous iron and ascorbate, and lowered the pro-oxidant effect of ferrous iron in oil emulsion. Addition of ferric or ferrous iron increased but Hb did not have any effect on the TBARS values of raw meat homogenates. The reaction mechanisms of superoxide and the superoxide-generating systems on the prooxidant effect of various iron sources indicated that .O2- was a strong oxidizer rather than a reducing agent, and the antioxidant effect of XOD system in oil was caused by the oxidation of ferrous iron to the ferric form by .O2- and/or H2O2.

Expression, purification, and characterization of a familial amyotrophic lateral sclerosis-associated D90A Cu,Zn-superoxide dismutase mutant

Cu,Zn-superoxide dismutase (SOD) is known to be a locus of mutation in familial amyotrophic lateral sclerosis (FALS). We cloned the FALS mutant, D90A, and wild-type of human Cu,Zn-SOD, overexpressed them in E. coli, purified the proteins, and studied their properties. We investigated their enzymic activities for catalyzing the dismutation of superoxide anions and the generation of free radicals with H2O2 as a substrate. Our results showed that both wild-type and mutant enzymes have identical dismutation activities. However, the hydroxyl radical-generating function of the D90A mutant, as measured using a 2,2'-azinobis-(3-ethylbenzthiazoline-6-sulfonate), was enhanced relative to that of the wild-type enzyme. Catalysis of this reaction by D90A was more sensitive to inhibition by the copper chelators, penicillamine and diethyldithiocarbamate, than was catalysis by wild-type Cu,Zn-SOD. Our study suggests that this gain-of-function of FALS mutant may, in part, be responsible for the development of FALS symptoms.

Identification of toxin A-negative, toxin B-positive Clostridium difficile by PCR

Toxigenic strains of Clostridium difficile have been reported to produce both toxins A and B nearly always, and nontoxigenic strains have been reported to produce neither of these toxins. Recent studies indicate that it is not always true. We established a PCR assay to differentiate toxin A-negative, toxin B-positive (toxin A-, toxin B+) strains from both toxin-positive (toxin A+, toxin B+) strains and both toxin-negative (toxin A-, toxin B-) strains as an alternative to cell culture assay and enzyme-linked immunosorbent assay (ELISA). By using the PCR primer set NK11 and NK9 derived from the repeating sequences of the toxin A gene, a shorter segment (ca. 700 bp) was amplified from toxin A-, toxin B+ strains compared to the size of the segment amplified from toxin A+, toxin B+ strains (ca. 1,200 bp), and no product was amplified from toxin A-, toxin B-strains. We examined a total of 421 C. difficile isolates by PCR. Of these, 48 strains showed a shorter segment by the PCR, were negative by ELISAs for the detection of toxin A, and were positive by cell culture assay. Although the cytotoxin produced by the toxin A-, toxin B+ strains was neutralized by anti-toxin B serum, the appearance of the cytotoxic effects on Vero cell monolayers was distinguishable from that of toxin A+, toxin B+ strains. By immunoblotting, the 44 toxin A-, toxin B+ strains were typed to serogroup F and the remaining four strains were serogroup X. Pulsed-field gel electrophoresis separated the 48 strains into 19 types. The PCR assay for the detection of the repeating sequences combined with PCR amplification of the nonrepeating sequences of either the toxin A or the toxin B gene is indicated to be useful for differentiating toxin A-, toxin B+ strains from toxin A+, toxin B+ and toxin A-, toxin B- strains and will contribute to elucidation of the precise role of toxin A-, toxin B+ strains in intestinal diseases.

Rapid increase of cytosolic content of acetyl-CoA carboxylase isoforms in H9c2 cells by short-term treatment with insulin and okadaic acid

Mammalian acetyl-CoA carboxylase (ACC) is present in two isoforms, alpha and beta, both of which catalyze formation of malonyl-CoA by fixing CO2 into acetyl-CoA. ACC-alpha is highly expressed in lipogenic tissues whereas ACC-beta is a predominant form in heart and skeletal muscle tissues. Even though the tissue-specific expression pattern of two ACC isoforms suggests that each form may have a distinct function, existence of two isoforms catalyzing the identical reaction in a same cell has been a puzzling question. As a first step to answer this question and to identify the possible role of ACC isoforms in myogenic differentiation, we have investigated in the present study whether the expression and the subcellular distribution of ACC isoforms in H9c2 cardiac myocyte change so that malonyl-CoA produced by each form may modulate fatty acid oxidation. We have observed that the expression levels of both ACC forms were correlated to the extent of myogenic differentiation and that they were present not only in cytoplasm but also in other subcellular compartment. Among the various tested compounds, short-term treatment of H9c2 myotubes with insulin or okadaic acid rapidly increased the cytosolic content of both ACC isoforms up to 2 folds without affecting the total cellular ACC content. Taken together, these observations suggest that both ACC isoforms may play a pivotal role in muscle differentiation and that they may translocate between cytoplasm and other subcellular compartment to achieve its specific goal under the various physiological conditions.

Acute lymphoblastic leukemia with maturation--a new entity with clinical significance

The diagnosis of 'ALL with maturation' (ALLm) is proposed. One hundred and one patients with untreated ALL were entered into this study. The diagnosis of ALLm was made when more than 20% of all nucleated elements in the bone marrow showed maturation beyond prolymphocytes by light microscopic examination. The mature-appearing leukemic cells showed the same immunophenotype to remaining lymphoblasts. The number of ALLm cases was 19 (18.8%). The mean age at presentation of ALLm was 29 +/- 18, older than that of 18 +/- 16 of the remaining typical ALL (ALLt) (P = 0.015). Remission was induced with daunorubicin, vincristine, prednisone and L-asparaginase. Only two of 19 ALLm patients achieved CR after 4 weeks induction chemotherapy. In contrast, 57 of 82 (69.5%) ALLt patients achieved CR after the same induction chemotherapy. There was no significant difference in immunophenotype of ALLm compared with ALLt. Labeling index of DNA topoisomerase IIalpha (TopoLI) was studied by immunohistochemistry. Initial TopoLI of ALLm (221 +/- 147) was much lower than that of ALLt (609 +/- 262, P = 0.005). Furthermore, the remaining leukemic cells after chemotherapy were not labeled with anti-DNA topoisomerase IIalpha. The P53 protein was expressed in nine of 18 ALLm cases (50.0%) and P-glycoprotein was not expressed in ALLm cases. Twelve of 19 ALLm cases were studied for carrying bcr/abl fusion by karyotyping and/or fluorescent in situ hybridization. Only two cases revealed bcr/abl fusion. In conclusion, ALLm is a separate entity of ALL which has a very poor clinical course and is independent of other prognostic factors. The morphologically mature leukemic cells are in resting GO phase.

Isolated bilateral abducens nerve palsy due to carotid cavernous dural arteriovenous fistula

Carotid cavernous dural arteriovenous fistula (DAVF) usually presents with conjunctival injection, proptosis, loss of visual acuity and ophthalmoplegia. There have been some carotid cavernous DAVF case reports presenting with isolated oculomotor, abducens and trochlear nerve palsy. We experienced a patient presenting with bilateral abducens nerve palsy and no other ocular signs who was diagnosed as carotid cavernous DAVF after conventional angiography. According to this case, carotid cavernous DAVF should be considered in the differential diagnosis of isolated bilateral abducens nerve palsy, in which case conventional angiography may be helpful in diagnosis.

Computer-assisted myocardial thickening analysis of gated MIBI SPECT images

RATIONALE AND OBJECTIVES

The purpose of this study is to use the relationship between the partial volume effect, count density, matrix size, and reconstruction filter in gated single photon emission computer tomography (SPECT) to recover myocardial thickness, and to validate measurements generated using a computer-assisted automatic contour method with a phantom model and with thickness changes measured by echocardiography.

METHODS

Regional myocardial contour was defined automatically using shape constraints, gray level thresholding, and a gradient method applied to gated technetium-99m (99mTc)-methoxy-isobutyl-isonitile (MIBI) SPECT images. A heart phantom with wall thickness ranging from 0.8 cm to 1.3 cm was constructed. SPECT images were acquired and reconstructed using different matrix sizes, count densities, and filters. Wall thickness determinations derived from the reconstructions made with each combination of matrix size, type of filter, and cutoff frequency were correlated with the measured thicknesses. The best combination was applied to the gated MIBI SPECT images of 55 patients who also had echocardiography and coronary arteriography. Count density measurements were made across each regional myocardial segment to evaluate wall thickness at end-diastole and end-systole. Systolic wall thickening measurements made with this automated computer-assisted contour technique were compared with echocardiographic measurements made from segments with normal perfusion and from regions containing infarcted tissue.

RESULTS

Different reconstruction filters and cutoff frequencies affected the accuracy of measurements of myocardial wall thickness determined from gated myocardial SPECT images. A matrix size of 64 x 64, with a minimum of 10 counts/pixel/frame, and use of a Hanning filter with 0.5 cyc/cm cutoff frequency gave the best combination for myocardial thickness determination and spatial resolution. Application of these factors to the phantom yielded results that correlated very well with the thickness measurements (r = 0.986, P < 0.001). Application of the technique to the clinical SPECT studies yielded measurements of myocardial wall thickening that were not significantly different from that determined by echocardiography.

CONCLUSION

Computer-assisted contour analysis of gated SPECT images enables accurate determination of regional wall thickening using the count density changes within each myocardial segment.

Prooxidant effects of ferrous iron, hemoglobin, and ferritin in oil emulsion and cooked-meat homogenates are different from those in raw-meat homogenates

Oil emulsion and raw and cooked tissue homogenates were used to determine the mechanisms of various iron forms on the catalysis of lipid peroxidation. Flax oil (0.25 g) was blended with 160 mL maleate buffer (0.1 M, pH 6.5) to prepare an oil emulsion. Raw or cooked turkey leg meat was used to prepare meat homogenates. Samples were prepared by adding iron from each of the various sources, reactive oxygen species, or enzyme (xanthine oxidase and superoxide dismutase) systems into the oil emulsion or meat homogenates. In oil emulsion and cooked-meat homogenates, ferrous iron and hemoglobin had strong prooxidant effects, but ferritin became prooxidant only when ascorbate was present. Hemoglobin and ferritin had no prooxidant effect in raw-meat homogenates. The status of heme iron and the released iron from hemoglobin had little effect on the prooxidant effect of hemoglobin in oil emulsion and cooked meat homogenate systems. The prooxidant effect of ferrous iron in oil emulsion and cooked-meat homogenates disappeared in the presence of superoxide (.O2-), H2O2, or xanthine oxidase systems. In raw-meat homogenates, however, ferrous had strong prooxidant effects even in the presence of .O2-, or H2O2. The status of free iron was the most important factor in the oxidation of oil emulsion and cooked-meat homogenates but the impact in raw-meat homogenates was small.

Ribosomal DNA replication in the fission yeast, Schizosaccharomyces pombe

We have employed genetic and two-dimensional (2D) gel electrophoretic methods to identify replication initiation, pausing, and termination sites in the tandem ribosomal DNA (rDNA) repeats of the fission yeast, Schizosaccharomyces pombe. An autonomously replicating sequence (ARS) element, ars3001, maps to a 2.3-kb restriction fragment spanning the junction between the nontranscribed spacer (NTS) and the external transcribed spacer upstream of the ribosomal RNA genes, and 2D gel analysis shows that replication initiates in the NTS portion of the same fragment. A pause region at the 3' end of the rRNA genes inhibits forks from entering these genes counter to the direction of transcription. Thus, most forks move through the genes in the same direction as transcription. In these respects, fission yeast rDNA replication resembles that in the budding yeast, Saccharomyces cerevisiae, and in multicellular eukaryotic organisms. A feature which, so far, has been detected only in fission yeast is the pausing of replication forks in a broad region near the 5.8S rRNA gene.

DNA cleavage by hydroxyl radicals generated in the Cu,Zn-superoxide dismutase and hydrogen peroxide system

To study the catalytic activity of Cu,Zn-superoxide dismutase (SOD) in the generation of hydroxyl radical (.OH) from H2O2, we investigated the mechanism of DNA cleavage mediated by human Cu,Zn-SOD and H2O2. When plasmid DNA was incubated with 5 microM Cu, Zn-SOD and 1.0 mM H2O2, DNA cleavage occurred within 15 min. A spectrophotometric study using a 2,2'-azinobis-(3-ethylbenzthiazoline-6-sulfonate) (ABTS) showed that free .OH formation was proportional to concentrations of Cu,Zn-SOD and H2O2. .OH formation and DNA cleavage were inhibited by hydroxyl radical scavengers such as cyanide, azide, and formate. These results indicated that .OH generated early in the peroxidative reaction of Cu,Zn-SOD with H2O2 was implicated in DNA cleavage. Incubation with H2O2 resulted in a time-dependent release of copper ions from the Cu,Zn-SOD molecule. The released copper ions then likely participated in a Fenton-like reaction to produce .OH that may have caused DNA cleavage. Evidence that DTPA protected the DNA cleavage induced by the Cu,Zn-SOD/H2O2 system supports this mechanism. We suggest that DNA cleavage is mediated in the Cu,Zn-SOD/H2O2 system via the generation of .OH by a combination of the peroxidative reaction of Cu,Zn-SOD and the Fenton-like reaction of free copper ions released from oxidatively damaged SOD.

Fragmentation of human Cu,Zn-superoxide dismutase by peroxidative reaction

We investigated the fragmentation of human Cu,Zn-superoxide dismutase (SOD) by H2O2. When Cu,Zn-SOD was incubated with H2O2, the fragmentation of protein proceeded rapidly within 1 min. The amounts of .OH radical formed in the Cu,Zn-SOD/H2O2 system reached a maximum in about 3 min. This result suggested that .OH was implicated in the fragmentation step. Copper ions released from Cu,Zn-SOD were gradually increased up to 30 min after starting the incubation with H2O2 in a time-dependent manner. However, the fragmentation was not inhibited by 5 mM DTPA. The results suggested that the fragmentation of Cu,Zn-SOD by H2O2 was due to the peroxidative reaction of SOD rather than the Fenton-like reaction by free copper released from oxidatively damaged SOD. A radical scavenger, azide anion, inhibited the fragmentation of Cu,Zn-SOD and the formation of .OH whereas ethanol did not. These results indicated that azide anions had easy access inside the active channel of Cu,Zn-SOD and thus protected the damage of the enzyme by .OH radicals whereas neutral alcohols stayed outside the active channel and could hardly intercept the newly-formed .OH radicals. Thus we conclude that the fragmentation of Cu,Zn-SOD by H2O2, is due to the oxidative damage resulting from free .OH radicals generated by the peroxidative reaction of SOD.

Effect of egg size and strain and age of hens on the solids content of chicken eggs

A study was conducted to determine the effect of egg size and the age and strain of hens on the content of egg solids. Eggs were obtained from commercial farms from four strains of hens with similar age groups and received diets formulated to contain the same dietary energy and protein levels across the strains within a farm. Eggs were collected on 2 different d when the flocks reached the average ages of 28, 55, 75, and 97 wk. The eggs collected form each farm were pooled and sorted by size. Each individual egg was used as a replicate for yolk:white ratio; however, five yolks, five whites, and five whole eggs from each strain at each age period were pooled, homogenized, and then used as a replicate to determine the solids contents of yolk, white, and whole eggs. The yolk:white ratio of eggs from 28-wk-old hens was the lowest, that from 55- and 78-wk-old hens was the highest, and that from 97-wk-old hens was intermediate; however, the solids content (percentage) of whole eggs increased with the age of the hens. The solids content of egg white was highest in eggs from 28-wk-old hens. The white solids content of extra large eggs was greater than that of medium eggs, and yolk solids increased with egg size; however, the solids of whole egg were not affected by egg size. The strain of hens had a significant effect on the solids of whole egg, white, and yolk; however, the strain effect on yolk:white ratio was not significant. The results showed that young (28-wk-old) and old birds (97-wk-old) produced eggs with low solids content and intermediate aged hens (55- to 78-wk-old) produced eggs with high solids content. Therefore, it may be more beneficial for egg producers and processors to use young (28-wk-old) and old birds (97-wk-old) for table egg production and birds of intermediate age (55- to 78-wk-old) for liquid egg production.

Peroxidative activity of human Cu,Zn-superoxide dismutase

In addition to the usual superoxide dismutation activity, Cu,Zn-superoxide dismutase (SOD) has a peroxidative function that utilizes its own dismutation product, H2O2 as a substrate. The peroxidative activity of human Cu,Zn-SOD was studied by using a chromogen, 2,2'-azinobis-(3-ethylbenzthiazoline-6-sulfonate) (ABTS) which reacts with OH radicals to form ABTS+. The optimal pH for the peroxidative activity of human Cu,Zn-SOD was 7.6-9.5. The peroxidative activity retained about 50% of the maximum activity when exposed at 40 degrees C for 5 min. The peroxidative activity showed a typical Michaelis-Menten kinetics for ABTS and H2O2 whose K(m) values were 16 microM and 9.3 mM, respectively. The peroxidative activity of human Cu,Zn-SOD was inhibited about 60% by the copper chelator, diethyldithiocarbamate (DDC) at 10 microM while the dismutation activity was not inhibited under a similar condition. We found that there are differences in the effects of temperature and DDC on the dismutation and peroxidative activities of human Cu,Zn-SOD. These results suggest that the amino acid residues which affect the activities of this enzyme may be different between dismutation and peroxidation.

NMR structure determination of a novel conotoxin, [Pro 7,13] alpha A-conotoxin PIVA

A high-resolution solution conformation of a novel conotoxin, [Pro 7,13] alpha A-conotoxin PIVA, GCCGSYPNAACHPCSCKDROSYCGQ-NH2, has been determined by two-dimensional 1H NMR methods and distance geometry calculations. The total of 324 NOE-derived interproton distance restraints including 33 long-range NOE restraints as well as 11 phi and 7 chi 1 torsion angle restraints was used for computation of structures. Back-calculation from the experimental NOE spectrum has provided 49 new NOE restraints and yielded the final R-factors of Ra = 0.641 and Rb = 0.157. The final RMSD values are 0.90 and 1.16 A for the backbone and the heavy atoms, respectively. The C-terminal half of the molecule involving the residues 12-24 is extremely well-defined with a backbone RMSD value of 0.56 A, whereas the N-terminal 3-11 disulfide loop is relatively flexible, possessing a backbone RMSD value of 1.09 A. The [Pro 7,13] alpha A-conotoxin PIVA does not contain any significant secondary structure although the 21S-24G nearly completes one turn of a 3(10) helix. The overall protein fold is largely maintained by the three disulfide bridges of 2-16, 3-11, and 14-23. The presence of the three disulfide bridges imposes geometric constraints that force the molecule to form six continuous bends involving the following residues: 3C-5S, 7P-10A, 12H-14C, 15S-17K, 17K-19R, and 21S-25Q. The overall shape of the [Pro 7,13] alpha A-conotoxin PIVA can be described as an "iron". Residues 15S-19R form a loop that protrudes out of the "bottom plate" formed by the rest of the protein and constitute the handle of the iron. The N-terminal tip of the molecule is relatively immobile due to attractive electrostatic interactions between the gamma-hydroxyl group of 20 Hyp and the phenolic hydroxyl group of 22Y. The flexible 3-11 disulfide loop consists mostly of hydrophobic residues, while the best-defined 14-23 disulfide loop contains the highly charged hydrophilic 15S-19R "handle" domain exposed to the exterior of the protein. Binding to nicotinic acetylcholine receptor can be mediated through two different types of interactions: one involving the aromatic hydrophobic residues such as 6Y and 12H and the other involving the positively charged hydrophilic side chain of the 19R. The side chain of the 19R in the [Pro 7, 13] alpha A-conotoxin PIVA and that of the 9R of the alpha-conotoxin G1, and also the side chains of the 12H and 6Y in the former and those of 10H and 11Y in the latter can be aligned to point to the same direction when the corresponding backbone atoms are superimposed to an RMSD value of 2.5 A.

Chromosomal numerical aberrations in gastric carcinoma: analysis of eighteen cases using in situ hybridization

Paraffin-embedded tumor cells of 18 cases of gastric carcinoma were hybridized with digoxigenin-labeled repetitive DNA probes specific for the centromeric regions of chromosomes X, Y, 1, 2, 3, 4, 6, 7, 8, 9, 10, 11, 12, 15, 16, 17, 18, and 20. All cases demonstrated numerical chromosomal aberrations. The most exciting aberration, polysomy (five or more copies) of several chromosomes, was found in all cases except a case of mucinous adenocarcinoma, which showed trisomy 9 as the sole chromosomal numerical aberration. In nine cases of tubular adenocarcinoma, poorly-differentiated polysomies of several chromosomes were the consistent numerical aberration and monosomy 7, 18(2 cases each), 10, and 17(1 case each) were also found. In moderately-differentiated tubular adenocarcinoma all three cases also showed polysomies of several chromosomes. The total number of extra chromosomes (polysomy was counted as 5 copies) was higher in the intestinal type (mean 20.9) than in the diffuse type (mean 14.1). Regional lymph node metastasis, vein invasion, or perineural invasion was not related to any specific chromosomal numerical aberration in gastric cancer. Chromosomes X, 1, 2, 3, 4, 15, 17, and 20 had extra copies especially polysomy in most cases. However, chromosomes 7 and 18 revealed monosomy in many cases (31.3% and 33.3% respectively, and chromosome 9 and 11 revealed trisomy in 35.7% and 75% each. Numerically, the most conserved chromosome in gastric cancer was chromosome 12 (62.5%). By flow cytometry, two diploidy and 8 aneuploidy cases with the DNA indices from 1.30 to 1.85 were found.