Submillisecond folding of monomeric lambda repressor

The folding kinetics of a truncated form of the N-terminal domain of phage lambda repressor [lambda 6-85] has been investigated by using the technique of dynamic NMR. lambda 6-85 has been shown previously to fold in a purely two-state fashion. This allows the determination of folding and unfolding rates from simulation of the exchange-broadened aromatic resonances of Tyr-22. The folding kinetics were determined over a range of 1.35 to 3.14 M urea. The urea dependence of both folding and unfolding rate constants is exponential, suggesting that the rate-determining step is invariant at the urea concentrations studied. The folding and unfolding rates extrapolated to 0 M urea at 37 degrees C are 3600 +/- 400 s-1 and 27 +/- 6 s-1, respectively. The observed lambda 6-85 folding rate constant exceeds that of other fast-folding globular proteins by a factor of 14-54. The urea dependence of the folding and unfolding rate constants suggests that the transition state of the rate-determining step is considerably more exposed to solvent than previously studied protein-folding transition states. The surprising rapidity of lambda 6-85 folding and unfolding may be the consequence of its all-helical secondary structure. These kinetic results clearly demonstrate that all of the fundamental events of protein folding can occur on the submillisecond time scale.

The energy landscape of a fast-folding protein mapped by Ala-->Gly substitutions

A moderately stable protein with typical folding kinetics unfolds and refolds many times during its cellular lifetime. In monomeric lambda repressor this process is extremely rapid, with an average folded state lifetime of only 30 milliseconds. A thermostable variant of this protein (G46A/G48A) unfolds with the wild-type rate, but it folds in approximately 20 microseconds making it the fastest-folding protein yet observed. The effects of alanine to glycine substitutions on the folding and unfolding rate constants of the G46A/G48A variant, measured by dynamic NMR spectroscopy, indicate that the transition state is an ensemble comprised of a disperse range of conformations. This structural diversity in the transition state is consistent with the idea that folding chains are directed towards the native state by a smooth funnel-like conformational energy landscape. The kinetic data for the folding of monomeric lambda repressor can be understood by merging the new energy landscape view of folding with traditional models. This hybrid model incorporates the conformational diversity of denatured and transition state ensembles, a transition state activation energy, and the importance of intrinsic helical stabilities.

Avulsion fracture of the head of the fibula (the "arcuate" sign): MR imaging findings predictive of injuries to the posterolateral ligaments and posterior cruciate ligament

OBJECTIVE

The purpose of this study was to describe the significance of an avulsion fracture of the head of the fibula ("arcuate" sign) and its association with injuries of the knee on MR imaging.

MATERIALS AND METHODS

We conducted a retrospective search of 2318 patients who underwent conventional radiography and MR imaging after an episode of knee trauma. Patients were included in this study if they had an avulsion fracture of the head of the fibula revealed on conventional radiography and underwent arthroscopy. Thirteen patients, all of whom were men, satisfied the inclusion criteria. Ten patients underwent further explorative surgery. The clinical, radiographic, MR imaging, and surgical findings were then reviewed.

RESULTS

The avulsion fracture of the styloid process of the fibular head was apparently related to injuries of the arcuate complex in all 13 patients. Radiographically, the bony fragment was horizontally oriented and similar in size in most patients, ranging from 8 to 10 mm in length and from 2 to 5 mm in width. On MR imaging, the fibular avulsion was identified in 11 of the 13 patients. The other two patients had marrow edema in the fibular styloid process, although the avulsion fracture was not evident. All patients had injuries of the posterior cruciate ligament (six tibial avulsions, seven midsubstance tears). No patient had a tear of the anterior cruciate ligament. Disruption of the lateral collateral ligament was evident in seven patients, and one patient had a tear of the popliteal tendon. During surgery, six patients had disruption of the arcuate complex, but this disruption could not be identified on the MR images.

CONCLUSION

An avulsion fracture of the fibular head generally involves the styloid process and causes injury of some of the major stabilizers in the posterolateral corner. Avulsion fractures are strongly associated with disruption of the posterior cruciate ligament.

Microsecond protein folding through a compact transition state

Dynamic NMR methods have been employed to measure the folding and unfolding rate constants of two extremely fast-folding proteins. lambda 6-85, a truncated, monomeric form of the N-terminal domain of lambda repressor, refolds with a lifetime of approximately 250 microseconds. These methods have also been applied to a thermostable lambda 6-85 variant with alanine substituted for glycine residues 46 and 48 in the third helix (G46A/G48A). Both proteins exhibit linear ln (kf,u) versus [urea] plots, consistent with two-state folding for both proteins. When extrapolated to 0M urea, the data indicate that G46A/G48A folds with a lifetime of less than 20 microseconds. The slopes of the ln (kf,u) versus [urea] curves (mu and mf) indicate that the modest Gly-->Ala double mutation dramatically changes the transition state solvent accessibility. The transition state for lambda 6-85 has a fractional accessibility (mu/(mu-mf)) of 0.61, whereas the transition state for G46A/G48A is much more native-like, with a fractional accessibility of 0.16. The extraordinary change in the folding pathway that these mutations induce suggests that the intrinsic stability of helix 3 is an important determinant of the folding mechanism.

Differentiation of soft tissue benign and malignant peripheral nerve sheath tumors with magnetic resonance imaging

PURPOSE

The objective of this study was to differentiate the magnetic resonance (MR) imaging appearance of benign peripheral nerve sheath tumors (PNSTs) from that of malignant PNSTs.

MATERIALS AND METHODS

Twenty-six patients who underwent MR imaging and had a histologic diagnosis of benign (schwannoma, n=16; neurofibroma, n=1) or malignant (n=9) PNST were retrospectively reviewed. The size, location, shape, margin, and signal intensities of the tumors on precontrast and gadolinium-enhanced MR imaging were analyzed. In each patient, the presence or absence of split fat, target, and fascicular signs was determined.

RESULTS

The mean size of the benign PNSTs (3.4 cm, S.D.=2.5 cm) was significantly smaller than that of the malignant tumors (8.2 cm, S.D.=3.1 cm) (P<.001). Seventeen (65.4%) of the 26 tumors were spindle shaped or ovoid (12 benign and 5 malignant tumors). Contiguity with specific nerves was identified in 15 (88.2%) of the 17 benign PNSTs but in none of the malignant tumors (P<.05). Well-defined margins were noted in all 17 benign PNSTs but in only 3 (33.3%) of the 9 malignant tumors (P<.001). Five (55.6%) of the 9 malignant PNSTs but none of the benign tumors showed signal intensity change in adjacent soft tissue (P<.05). There was no significant difference in signal intensity between the benign and malignant tumors on T(1)-weighted, T(2)-weighted, and contrast-enhanced MR images. The split fat and target signs were present more frequently in the benign PNSTs than in the malignant PNSTs (P<.05).

CONCLUSIONS

Benign and malignant PNSTs are often spindle shaped. Recognition of contiguity with adjacent nerves, a well-defined margin, and the presence of the split fat sign may suggest benignity. Imaging features suggestive of malignancy can be a larger size and an infiltrative margin.

Brain injury after acute carbon monoxide poisoning: early and late complications

OBJECTIVE

The purposes of this article are to illustrate the variable CT and MRI features of carbon monoxide-induced brain injury and to discuss the underlying pathogenesis.

CONCLUSION

Carbon monoxide can produce different patterns of brain injury in the acute and delayed stages. CT and MRI are valuable in the delineation of disease extent and helpful for understanding the pathophysiologic mechanisms.

Osteochondral autografts for osteochondritis dissecans of the talus

Eighteen symptomatic advanced-stage osteochondritis dissecans (OCD) of the talus (Berndt and Harty stages III 7 and IV 11) in 17 patients were treated with multiple autogenous osteochondral cylindrical grafts. The mean time of follow-up was 36 months (range, 25-49). The average age at surgery was 22.7 years (range, 19-34). The mean size of defect of OCD was 13.6 mm x 7.2 mm. Two or three osteochondral grafts (6 or 7 mm in diameter and 15-20 mm in length) were harvested from the superomedial margin of the ipsilateral knee. A partial osteotomy of the medial malleolus or osteotomy of the distal lateral tibia was performed for all cases. Being evaluated by the Freiburg ankle score, 16 of 18 ankles (88.8%) had excellent and two (11.8%) had good results. "Second-look" arthroscopy of 16 ankles revealed consistency of the osteochondral grafts and congruity between grafts and native cartilage in 14 (87.5%), and a softening or fissuring of the osteochondral graft in two. Our results showed that this procedure provided an effective treatment for a symptomatic advanced-stage OCD of the talus.

MR imaging of bone marrow edema and joint effusion in patients with osteonecrosis of the femoral head: relationship to pain

OBJECTIVE

Our aim was to determine the occurrence of bone marrow edema and joint effusion and their relationship to pain in patients with osteonecrosis of the femoral head on the basis of MR imaging.

MATERIALS AND METHODS

There were 71 patients with osteonecrosis of the femoral head based on characteristic radiographic and MR imaging findings. All patients had surgical confirmation of the disease. Both hips were affected with osteonecrosis in 39 patients, whereas only one hip was involved in 31 patients. The last patient underwent an arthroplasty of one hip during the study and had only one hip imaged. We evaluated a total of 110 hips in this study, of which 98 were painful. We staged osteonecrosis of the femoral head, using the classification of Steinberg et al. The 31 unaffected hips served as controls. Bone marrow edema and joint fluid were evaluated on MR images. Bone marrow edema was defined as an ill-defined area of low signal intensity on T1-weighted images with corresponding high signal intensity on T2-weighted or inversion recovery images localizing to the femoral head, neck, and intertrochanteric region. The amount of joint fluid was graded from 0 to 3.

RESULTS

The peak of bone marrow edema occurred in stage III disease (72%); its odds ratio was seven times greater than that for stage I osteonecrotic hips. Effusions of a grade greater than or equal to 2 were seen most often in stage III disease (92%), compared with 10% in the control hips. With an effusion, bone marrow edema was 12.6 times greater when the hip was painful than when it was not.

CONCLUSION

Both bone marrow edema and joint effusions existed with a peak occurrence in stage III disease. Bone marrow edema seems to have a stronger association with pain than does joint effusion in osteonecrosis of the femoral head.

Localized nodular synovitis of the knee: MR imaging appearance and clinical correlates in 21 patients

OBJECTIVE

Localized nodular synovitis of the knee and pigmented villonodular synovitis are similar histologically. The purpose of this study was to evaluate the MR imaging appearance and clinical findings of localized nodular synovitis of the knee and to differentiate this condition from pigmented villonodular synovitis.

MATERIALS AND METHODS

A retrospective review of MR imaging of the knee was performed in 21 patients with histologically confirmed localized nodular synovitis. Surgical excision of the lesion was performed in all patients. The MR imaging appearances of the lesions were defined, and the clinical and surgical findings were reviewed.

RESULTS

All lesions presented as a solitary intraarticular mass. The mass originated from the synovial lining in different locations including the infrapatellar fat pad (n = 14), suprapatellar pouch (n = 5), and posterior aspect of the intercondylar notch (n = 2). A small (2.0-3.5 cm; mean diameter, 2.7 cm) ovoid mass (n = 13) was more common than a large (5.0-9.0 cm; mean diameter, 6.5 cm) polylobulated mass (n = 8). At surgery, a long pedicle attached the mass to the adjacent synovium in two patients, but this was observed on MR imaging in only one patient. The lesions showed intermediate (n = 15) or hyperintense (n = 6) signal intensity on T1-weighted images and heterogeneously high (n = 13) or low (n = 8) signal intensity with variable circular foci of low signal intensity on T2-weighted images. On T2-weighted images, linear regions of high signal intensity within the mass were seen in seven lesions. Prominent enhancement of the lesion with IV contrast administration was shown in all patients who were given contrast material (n = 10). Knee pain, joint swelling, and a palpable mass were the most frequent clinical manifestations. An acutely painful knee was noted in one patient who presented with torsion of an infrapatellar pedicle. Five patients complained of locking of the knee, but at physical examination, restricted terminal knee extension was noted in nine patients.

CONCLUSION

Localized nodular synovitis of the knee predominantly involves the infrapatellar fat pad. It may produce symptoms related to mechanical derangement of the knee. Although there is no typical MR appearance for this lesion, many features help to differentiate it from pigmented villonodular synovitis.

Structure and stability of monomeric lambda repressor: NMR evidence for two-state folding

The absence of equilibrium intermediates in protein folding reactions (i.e., two-state folding) simplifies thermodynamic and kinetic analyses but is difficult to prove rigorously. We demonstrate a sensitive method for detecting partially folded species based on using proton chemical shifts as local probes of structure. The coincidence of denaturation curves for probes throughout the molecule is a particularly stringent test for two-state folding. In this study we investigate a new form of the N-terminal domain of bacteriophage lambda repressor consisting of residues 6-85 (lambda 6-85) using nuclear magnetic resonance (NMR) and circular dichroism (CD). This truncated version lacks the residues required for dimerization and is monomeric under the conditions used for NMR. Heteronuclear NMR was used to assign the 1H, 15N, and backbone 13C resonances. The secondary and tertiary structure of lambda 6-85 is very similar to that reported for the crystal structure of the DNA-bound 1-92 fragment [Beamer, L. J., and Pabo, C. O. (1992) J. Mol. Biol. 227, 177-196], as judged by analysis of chemical shifts, amide hydrogen exchange, amide-alpha coupling constants, and nuclear Overhauser enhancements. Thermal and urea denaturation studies were conducted using the chemical shifts of the four aromatic side chains as local probes and the CD signal at 222 nm as a global probe. Plots of the fraction denatured versus denaturant concentration obtained from these studies are identical for all probes under all conditions studied. This observation provides strong evidence for two-state folding, indicating that there are no populated intermediates in the folding of lambda 6-85.

Observation of a charged charmoniumlike structure in e+ e- → π+ π- J/ψ at sqrt[s] = 4.26 GeV

We study the process ee+ e- → π+ π- J/ψ at a center-of-mass energy of 4.260 GeV using a 525  pb(-1) data sample collected with the BESIII detector operating at the Beijing Electron Positron Collider. The Born cross section is measured to be (62.9±1.9±3.7)  pb, consistent with the production of the Y(4260). We observe a structure at around 3.9  GeV/c2 in the π(±)J/ψ mass spectrum, which we refer to as the Z(c)(3900). If interpreted as a new particle, it is unusual in that it carries an electric charge and couples to charmonium. A fit to the π(±)J/ψ invariant mass spectrum, neglecting interference, results in a mass of (3899.0±3.6±4.9)  MeV/c2 and a width of (46±10±20)  MeV. Its production ratio is measured to be R = (σ(e+ e- → π(±)Z(c)(3900)(∓) → π+ π- J/ψ)/σ(e+ e- → π+ π- J/ψ)) = (21.5±3.3±7.5)%. In all measurements the first errors are statistical and the second are systematic.

Painful conditions affecting the first metatarsal sesamoid bones

The sesamoid bones of the first metatarsal exhibit a special anatomic configuration, enveloped by the tendons of the flexor hallucis brevis and lying within the capsule of the first metatarsophalangeal joint. Painful conditions of the hallux sesamoid bones are many and include congenital, traumatic, arthritic, infectious, and ischemic conditions. Because of the complex anatomy and the numerous pain-sensitive structures in the region of the first metatarsophalangeal joint, a differential diagnosis can be challenging. The imaging examination should always begin with conventional radiography, including special axial and lateromedial views of the sesamoid bones. In cases in which results of routine radiography are inconclusive, scintigraphy, conventional or computed tomography, xeroradiography, or magnetic resonance imaging can be used. A thorough understanding of the anatomy; pathophysiology; and clinical, laboratory, and imaging findings is often helpful in the establishment of a diagnosis and management plan for painful conditions of the hallux sesamoid bones.

Six-month efficacy of platelet-rich plasma for carpal tunnel syndrome: A prospective randomized, single-blind controlled trial

Recently, a few small reports with short follow-up period have shown clinical benefits of platelet-rich plasma (PRP) for peripheral neuropathy including one pilot study and one small, non-randomized trial in patients with carpal tunnel syndrome (CTS). Therefore, we conducted a randomized, single-blind, controlled trial to assess the 6-month effect of PRP in patients with CTS. Sixty patients with unilateral mild-to-moderate CTS were randomized into two groups of 30, namely the PRP and control groups. In the PRP group, patients were injected with one dose of 3 mL of PRP using ultrasound guidance and the control group received a night splint through the study period. The primary outcome measure was the visual analog scale (VAS) and secondary outcome measures included the Boston Carpal Tunnel Syndrome Questionnaire (BCTQ) score, the cross-sectional area (CSA) of the median nerve (MN), electrophysiological findings of the MN, and finger pinch strength. The evaluation was performed before treatment and at 1, 3, and 6 months post-injection. The PRP group exhibited a significant reduction in the VAS score, BCTQ score, and CSA of MN compared to the those of control group 6 months post-treatment (p < 0.05). Our study demonstrates that PRP is a safe modality that effectively relieves pain and improves disability in the patients with CTS.

Differential gene expression of scopolamine-treated rat hippocampus-application of cDNA microarray technology

The molecular study of learning and memory has been concentrated at muscarinic acetylcholine receptors and their associating signaling molecules. To explore alternative pathways we applied human cDNA microarray and searched for differentially expressed genes in the hippocampus of scopolamine-treated rat. Interspecies hybridization using human cDNA microarray to analyze scopolamine-treated rat hippocampus exhibited a minor difference for the expression profile compared to normal control with standard deviation of 0.08-fold in ratio. Based on differential expression, forty-two genes were selected for further analysis from 9,600 candidate genes on the array. Twenty-eight genes were validated by semi-quantitative reverse transcription polymerase chain reaction (RT-PCR) using primer pairs against rat orthologs. The broad spectrum of the differentially expressed genes indicated an overall cellular response upon scopolamine treatment. In addition to genes associated with muscarinic receptor signaling pathways, we have disclosed genes associated with novel pathways such as apoptosis, cytoskeleton reconstruction, protein trafficking, cell differentiation, and genes without a clear role. Our result should provide an insight into the molecular study of scopolamine-induced memory impairment.

Perfusion characteristics of late radiation injury of parotid glands: quantitative evaluation with dynamic contrast-enhanced MRI

We aimed to quantitatively investigate the alteration of parotid perfusion after irradiation using dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) based on a two-compartment tracer kinetic model. This study enrolled 19 patients (53.2 +/- 14.9 years) treated by head and neck radiotherapy and 19 age-relevant and sex-matched subjects as a control group. Perfusion parameters (K ( el ), k (21) and A) of parotid glands were analyzed based on the Brix model from T1-weighted DCE-MRI. Suitability of the Brix model was evaluated via Monte Carlo simulation for the goodness-of-fit. Analysis of nonlinear goodness-of-fit showed that the Brix model is appropriate in evaluating the parotid perfusion (R(2) = 0.938 +/- 0.050). The irradiated parotid glands showed significantly lower K ( el ) (P < 0.0005) and k (21) (P < 0.05) and consequently significantly higher value of peak enhancement (P < 0.0005) and time-to-peak (P < 0.0005) compared with non-irradiated ones, suggestive of gradual and prolonged accumulation and delayed wash-out of contrast agent due to increased extracellular extravascular space and decreased vascular permeability in the irradiated glands. Linear regression analysis showed dose-dependent perfusion changes of the irradiated parotid glands. We conclude that quantitative DCE-MRI is a potential tool in investigating parotid gland perfusion changes after radiotherapy.

Role of nucleolar organiser regions in differentiating malignant from benign tumours of the colon

An argyrophilic technique (AgNOR) was applied to paraffin wax sections of 12 tubular adenomas, 17 villous adenomas with moderate and severe atypia, and 21 colonic adenocarcinomas. The range of the mean number of nucleolar organiser regions (NORS) per nucleus was 1.54-3.28 (99% CI 2.29-3.04) for tubular adenomas 3.07-4.36 (2.98-4.43), and 3.60-5.02 (3.74-4.69) for villous adenomas with moderate and severe atypia, respectively, and 5.53-9.33 (6.15-8.54) for highly differentiated adenocarcinomas. The number of AgNORs permitted differentiation among the three groups. The differences observed were significant. Malignant tumour cells were characterised by a large number of AgNORs which were small in size and showed a scattered distribution. Nuclei of tubular adenoma and villous adenoma with moderate atypia had only a small number of large sized AgNORs in a clustered distribution. It is suggested that this method distinguishes malignant epithelial cells from benign cells of colon, even those with severe atypia, and that it is a useful adjunct to diagnostic histopathology.

Requirements for activity of the yeast mitotic recombination hotspot HOT1: RNA polymerase I and multiple cis-acting sequences

When inserted at novel locations in the yeast genome, the Saccharomyces cerevisiae recombination hotspot HOT1 stimulates mitotic exchange in adjacent sequences. HOT1 is derived from the rDNA repeat unit, and the sequences required for the recombination-stimulatory activity closely correspond to the rDNA transcription enhancer and initiation site, suggesting there is an association between high levels of RNA polymerase I transcription and increased recombination. To directly test whether RNA polymerase I is essential for HOT1 activity, a subunit of RNA polymerase I was deleted in a strain in which rRNA is transcribed by RNA polymerase II. HOT1 is completely inactive in this strain. Deletion analysis and site-directed mutagenesis were used to further define the sequences within the rDNA enhancer required for HOT1 activity. These studies show that the enhancer contains at least four distinct regions that are required for hotspot activity. In most cases mutations in these regions also decrease transcription from this element, further confirming the association of recombination and transcription.

Risk factors and incidence of postoperative delirium in elderly Chinese patients

OBJECTIVES

To investigate the incidence of postoperative delirium among elderly patients and to examine the interrelationship between basic vulnerability and precipitating factors for delirium.

DESIGN AND METHODS

This was a prospective cohort study. Data were collected in a tertiary medical center in Taipei, Taiwan. From the 1st to the 5th postoperative day, nurses assessed patients using a confusion-screening tool. Patients with signs of delirium were closely examined for changes in behavior and cognitive status and vital signs, and laboratory data were collected to further validate the organic etiology of delirium. Patients were finally diagnosed according to the DSM-IV criteria in consensus meetings.

SUBJECTS

Seven hundred and one elderly patients, that were admitted consecutively for elective orthopedic or urologic surgery, were enrolled in this study. All subjects met the following criteria: (1) 65 years of age or older; (2) able to communicate orally in Chinese, and (3) not unconscious, delirious, deaf, or aphasic upon admission.

RESULTS

The overall incidence of delirium among these subjects was 5.1%. Logistic regression analysis identified that older age and preexisting cognitive impairment were vulnerability factors, and that the use of psychoactive drugs was a precipitating factor for delirium. Patients with both basic vulnerability and the precipitating factor had a 56-fold increased probability of delirium (0.28 vs. 0.005 in comparison with those who did not exhibit these factors).

CONCLUSION

Few risk factors of postoperative delirium in the older Chinese sample were identified. The only modifiable risk factor appears to be the use of psychoactive drugs.

Protection of tea melanin on hydrazine-induced liver injury

The protective activity of melanin derived from tea (MDFT) was studied using hydrazine as a DNA-reactive chemical agent. Intra-peritoneal administration of MDFT at the doses of 5 or 20 mg/kg dose-dependently prevented liver toxicity induced by hydrazine in rats. It normalized rises in serum alanine transferase activity and a decrease in the glutathione level in the liver. It also reduced the hepatic malondialdehyde concentration. Monitoring the intensity of chemiluminescence showed that MDFT could prevent the production of free radicals that are generated owing to metabolic transformation of hydrazine. It also prevented the formation 8-hydroxy-deoxyguanosine (8-OH-dG) DNA adducts. The results obtained in vivo and in vitro suggest that MDFT confers marked protection of the liver against hydrazine-induced oxidative toxicity.

Detection of human parvovirus B19 in papillary thyroid carcinoma

To evaluate whether parvovirus B19, a common human pathogen, was also involved in papillary thyroid carcinoma (PTC), 112 paraffin-embedded thyroid specimens of benign nodules, papillary, medullary and follicular carcinomas, and normal controls were examined for B19 DNA and capsid protein by nested PCR, in situ hybridisation (ISH) and immunohistochemistry (IHC). The expression of the nuclear factor-κB (NF-κB) was investigated by IHC. The results showed B19 DNA commonly exists in human thyroid tissues; however, there were significant differences between PTC group and normal controls, and between PTC and nonneoplastic adjacent tissues (P<0.001). The presence of viral DNA in PTC neoplastic epithelium was confirmed by laser-capture microdissection and sequencing of nested PCR products. B19 capsid protein in PTC group was significantly higher than that of all the control groups and nonneoplastic adjacent tissues (P⩽0.001). Compared with control groups, the activation of NF-κB in PTC group was significantly increased (P⩽0.02), except for medullary carcinomas, and the activation of NF-κB was correlated with the viral protein presence (P=0.002). Moreover, NF-κB was colocalised with B19 DNA in the neoplastic epithelium of PTC by double staining of IHC and ISH. These results indicate for the first time a possible role of B19 in pathogenesis of PTC.

Volume-dependent overestimation of spontaneous intracerebral hematoma volume by the ABC/2 formula

BACKGROUND

Although the ABC/2 formula has been widely used to estimate the volume of intracerebral hematoma (ICH), the formula tends to overestimate hematoma volume. The volume-related imprecision of the ABC/2 formula has not been documented quantitatively.

PURPOSE

To investigate the volume-dependent overestimation of the ABC/2 formula by comparing it with computer-assisted volumetric analysis (CAVA).

MATERIAL AND METHODS

Forty patients who had suffered spontaneous ICH and who had undergone non-enhanced brain computed tomography scans were enrolled in this study. The ICH volume was estimated based on the ABC/2 formula and also calculated by CAVA. Based on the ICH volume calculated by the CAVA method, the patients were divided into three groups: group 1 consisted of 17 patients with an ICH volume of less than 20 ml; group 2 comprised 13 patients with an ICH volume of 20 to 40 ml; and group 3 was composed of 10 patients with an ICH volume larger than 40 ml.

RESULTS

The mean estimated hematoma volume was 43.6 ml when using the ABC/2 formula, compared with 33.8 ml when using the CAVA method. The mean estimated difference was 1.3 ml, 4.4 ml, and 31.4 ml for groups 1, 2, and 3, respectively, corresponding to an estimation error of 9.9%, 16.7%, and 37.1% by the ABC/2 formula (P<0.05).

CONCLUSION

The ABC/2 formula significantly overestimates the volume of ICH. A positive association between the estimation error and the volume of ICH is demonstrated.

Acute anterior cruciate ligament stump entrapment in anterior cruciate ligament tears: MR imaging appearance

PURPOSE

To describe the magnetic resonance (MR) imaging appearance of anterior cruciate ligament (ACL) stump entrapment in patients who presented with decreased knee extension after rupturing the ACL.

MATERIALS AND METHODS

MR images in 15 patients who had presented with a block to terminal knee extension after sustaining an ACL tear were retrospectively reviewed. The MR imaging appearances of entrapped ACL stumps were defined and correlated with arthroscopic and histologic findings.

RESULTS

The entrapped ACL stumps had two distinct appearances. Type 1 stumps (n = 11) were characterized by a nodular mass located at the anterior aspect of the intercondylar notch, interposed between the lateral femoral condyle and tibia. Type 2 stumps (n = 4) were characterized by a tonguelike free end and angulation of the stump. Histologic evaluation of the resected specimens showed distorted ACL fibers intermixed with variable fibrosis and inflammation.

CONCLUSION

Entrapment of an ACL stump can limit knee extension. The two observed appearances of entrapped ACL stumps likely represent two points along a spectrum of appearances, which possibly includes the cyclops lesion.

Incidentally detected enhancing breast lesions on chest computed tomography

Objective

To evaluate the nature and imaging appearance of incidental enhancing breast lesions detected on a routine contrast-enhanced chest CT.

Materials and Methods

Twenty-three patients with incidental enhancing breast lesions on contrast-enhanced chest CT were retrospectively reviewed. The breast lesions were reviewed by unenhanced and enhanced CT, and evaluated by observing the shapes, margins, enhancement patterns and backgrounds of breast lesions. A histopathologic diagnosis or long-term follow-up served as reference standard.

Results

Sixteen (70%) patients had malignant breast lesions and seven (30%) had benign lesions. In 10 patients, the breast lesions were exclusively detected on contrast-enhanced CT. Using unenhanced CT, breast lesions with fibroglandular backgrounds were prone to be obscured (p < 0.001). Incidental primary breast cancer showed an non-significant trend of a higher percentage irregular margin (p = 0.056). All of the four incidental breast lesions with non-mass-like enhancement were proven to be malignant.

Conclusion

Routine contrast-enhanced chest CT can reveal sufficient details to allow for the detection of unsuspected breast lesions, in which some cases may be proven as malignant. An irregular margin of incidental enhancing breast lesion can be considered a suggestive sign of malignancy.

Differential gene expression of livers from ApoE deficient mice

A genomic survey for differentially expressed genes was performed to livers of ApoE deficient mice using human cDNA microarray containing approximately 9,000 human cDNA clones. Due to the homology between mouse and human, hybridization was performed at lower stringency condition, 10 degrees below the regular hybridizing temperature. Gene expression profiles of livers corresponding to high levels of blood cholesterol were generated at genomic scale. Thirty-seven genes were randomly selected from a pool of differentially expressed genes and subjected to semi-quantitative RT-PCR, further confirmed the result from microarray hybridization. These included genes associated with atherosclerosis, and novel genes that implied novel pathways correlated to high levels of blood cholesterol. It is promising using human cDNA microarray, the most complete collection among all species, to study other mammalian systems with satisfying speed and accuracy.