[A case of right ventricular myxoma]

A 43-year-old male presented with a history of occasional syncopal episodes and general fatigue for 4 months. On admission, a grade 4/6 systolic murmur was noted, and the electrocardiogram demonstrated frequent premature supraventricular beats. An echocardiogram revealed the presence of a multi-lobular mass in the right ventricle which prolapsed into the pulmonary artery during systole. Ultrafast computed tomography demonstrated a pedunculated mass arising from the right ventricular free well. At operation, the soft mass was excised through the tricuspid valve under cardiac arrest. Histopathologically, the tumor was diagnosed as a myxoma. Myxoma of the right ventricle occurs very rare. We review the literature relevant to cardiac myxoma.

Morphology of capillary-like structures in a three-dimensional aorta/collagen gel culture

The morphology of capillary-like tubes was investigated by electron microscopy (TEM and SEM) using an in vitro model of capillarogenesis (aorta/collagen type I gel). This model allowed morphological comparisons with in vivo capillaries and an evaluation of the functional maturity of the endothelium to be made. The lumina developing in vitro were demarcated by endothelial cells of varying thickness (0.1-2 microns). Pericytes were resting on the outside. The endothelial cells were characterized by contacts of varying length with tight and gap junctions and occasional indentations. The inner surface exhibited areas both with pronounced and without any endocytotic activity. In addition to a large Golgi apparatus, a varying number of cell organelles occurred depending on the thickness of the endothelium. Bundles consisting of microfilaments were often located underneath the outer cell membrane and in the vicinity of contact areas. A lamina densa was in the process of formation. The capillaries grown in vitro closely resembled those in vivo and showed a high degree of differentiation. Hence, this in vitro model allows the study of a number of functions of endothelial cells.

Formation of new capillary-like tubes in a three-dimensional in vitro model (aorta/collagen gel)

Direct sprouting (angiogenesis) does not occur during the formation of capillary-like tubes in an aorta/ collagen gel in the in vitro model. However, emigration of cells which stretch, arrange themselves side by side, form contacts (unspecific, tight and gap junctions), develop a lumen and show differentiation of endothelial cells (including the formation of a lamina densa and the appearance of pericytes) have been observed, i.e. vasculogenesis occurs. The origin of long, stretched cells is not known with certainty. They possibly represent smooth muscle cells. In addition, other cell types have been found, such as fibrocyte-like and fibroblast-like cells, elastoblasts, fat cells, monocytes and macrophages. All these cells are able to produce factors that promote the formation of new capillaries. Hence, a knowledge of these cells appears to be important for the analysis of in vitro systems. Moreover, the occurrence of these cell types must be considered when assessing possible effects.

COOH-terminal sequence of the cellular prion protein directs subcellular trafficking and controls conversion into the scrapie isoform

Efficient formation of scrapie isoform of prion protein (PrP(Sc)) requires targeting PrP(Sc) by glycophosphatidyl inositol (GPI) anchors to caveolae-like domains (CLDs). Redirecting the cellular isoform of prion protein (PrP(C)) to clathrin-coated pits by creating chimeric PrP molecules with four different COOH-terminal transmembrane domains prevented the formation of PrP(Sc). To determine if these COOH-terminal transmembrane segments prevented PrP(C) from refolding into PrP(Sc) by altering the structure of the polypeptide, we fused the 28-aa COOH termini from the Qa protein. Two COOH-terminal Qa segments differing by a single residue direct the transmembrane protein to clathrin-coated pits or the GPI form to CLDs; PrP(Sc) was formed from GPI-anchored PrP(C) but not from transmembrane PrP(C). Our findings argue that PrP(Sc) formation is restricted to a specific subcellular compartment and as such, it is likely to involve auxiliary macromolecules found within CLDs.

Coexisting peripheral nerve and cervical cord compression

STUDY DESIGN

The authors investigated the clinical usefulness of recording motor evoked potentials after transcranial magnetic stimulation in coexisting peripheral nerve and cervical cord lesions.

OBJECTIVE

To show that the measurement of central motor conduction time from the abductor policis brevis and the abductor digiti minimi can be used as a good screening method for double lesions involving peripheral nerves and the cervical cord.

SUMMARY OF BACKGROUND DATA

Transcranial magnetic stimulation has been used in the diagnosis of compressive cervical myelopathy. This technique could be useful in the assessment of patients with an entrapment neuropathy and cervical myelopathy.

METHODS

Motor evoked potentials after transcranial magnetic stimulation, compound muscle action potentials, and F waves after supramaximal peripheral nerve stimulation were recorded from the abductor policis brevis and the abductor digiti minimi. The central motor conduction time was calculated by subtracting the peripheral conduction time from the motor evoked potentials latency.

RESULTS

Ten patients with coexisting peripheral nerve and cervical cord lesions were evaluated. Two patients did not show satisfactory improvement after the decompression of the entrapment lesions, and six patients had hyperreflexia of lower limbs. In seven of these patients, the central motor conduction time was prolonged an average of 2.5 standard deviation of the normal value. The remaining two patients had spinal cord compression due to the ossification of the posterior longitudinal ligament. The spinal cord compression was demonstrated by magnetic resonance imaging, but the central motor conduction time was normal. Subjective symptoms improved in these two patients after decompressive surgery at the entrapment site alone.

CONCLUSIONS

Measurement of the central motor conduction time using motor evoked potentials is an ideal diagnostic approach for patients with coexisting entrapment neuropathy and cervical cord compression.

Cell-specific regulation of IRS-1 gene expression: role of E box and C/EBP binding site in HepG2 cells and CHO cells

Insulin receptor substrate 1 (IRS-1) is one of the major substrates of insulin receptor tyrosine kinase and mediates multiple insulin signals downstream. We have previously shown that the levels of IRS-1 mRNA varied in different tissues. To elucidate the molecular mechanisms of the tissue specific regulation of IRS-1, we have studied the cis-acting elements and transacting factors in CHO and HepG2 cells. Using the chloramphenicol acetyltransferase (CAT) assay with the various deletion mutants of the IRS-1 promoter-CAT fusion plasmids, several regions responsible for positive or negative regulation in each cell line were identified. A region from -1645 to -1585 bp, which regulated expression negatively in CHO cells and positively in HepG2 cells, was further analyzed. Within this region a fragment from -1645 to -1605 bp upregulated the IRS-1 promoter only in HepG2 cells, whereas a fragment from -1605 to -1585 bp downregulated only in CHO cells. In the gel mobility shift assay, several nuclear proteins that bind to these fragments were detected, and among them, two nuclear proteins that bind to a potential E box (nucleotide [nt] -1635 to -1630) and two nuclear proteins that bind to a potential C/EBP binding site (nt -1599 to -1591) were identified in HepG2 and CHO cells, respectively. CAT assays using promoters mutated at the E box or at the C/EBP binding site revealed that these sequences were responsible for cell-specific regulation of the IRS-1 gene. We therefore concluded that the two nuclear proteins that bind to the E box regulate IRS-1 gene expression positively in HepG2 cells and the two nuclear proteins that bind to the C/EBP binding site regulate it negatively in CHO cells.

Anatomy of the round ligament in female infants and children with an inguinal hernia

BACKGROUND

The ligament which runs along an inguinal hernia sac in females is believed to be the round ligament of the uterus. According to most standard textbooks, the round ligament of the uterus terminates at the labium majorum. This study examined the termination of the ligament.

METHODS

The anatomy of the ligament was examined in 248 female children (aged 1 month to 11 years) with an inguinal hernia. The anterior wall of the hernia sac, consisting of the inner and outer membranes, was opened and the inner membrane of the sac was pulled up with forceps; the hernia sac was then separated from the surrounding tissue. The termination of the ligament was observed.

RESULTS

The ligament did not end at the labium majorum but terminated in the hernia sac. The ligament was attached to the mid portion of the fallopian tube near the ovary.

CONCLUSION

These findings suggest that the ligament which runs along the hernia sac is the suspensory ligament of the ovary.

Small hepatocellular carcinoma on magnetic resonance imaging. Relation of signal intensity to angiographic and clinicopathologic findings

RATIONALE AND OBJECTIVES

The authors discuss the clinicopathologic features and angiographic vascularity of various signal intensity patterns on magnetic resonance (MR) imaging of small hepatocellular carcinomas (HCCs).

METHODS

Magnetic resonance images of 88 resected HCCs (< or = 3 cm) were obtained using T1- and T2-weighted spin-echo images and T1-weighted images after gadolinium (Gd)-DTPA administration. Images were compared with angiographic and histopathologic findings.

RESULTS

Forty HCCs (45%) were depicted on T1-weighted images, 51 (58%) on T2-weighted images, and 41 (49%) on T1-weighted images after Gd-DTPA administration. Overall, 64 (76%) were found on at least one image. On T1-weighted images, hyperintense HCCs histologically showed fatty metamorphosis and portal tracts within the tumor. On T2-weighted images, HCC hyperintensity correlated with expansive growth, peliotic change, and hypervascularity. By contrast, HCCs that were undetected or hypointense on T2-weighted images were well differentiated with replacing growth and portal tracts. On T1-weighted images after Gd-DTPA, hyperintense HCCs had peliotic change; undetected HCCs were well differentiated and hypovascular.

CONCLUSIONS

Histologic grade, vascularity, portal tracts and peliotic change correlate with MR signal intensity. For hyperintense HCCs on T1-weighted images and hypo- or isointense HCCs on T2-weighted images, treatment methods must be assigned with the consideration that HCCs may be receiving transsinusoidal and portal blood supplies.

Helical CT evaluation of arterial invasion in pancreatic tumors: comparison with angiography

BACKGROUND

Although helical computed tomography (HCT) has been widely employed for the evaluation of pancreatic tumors, its capability in the diagnosis of peripancreatic arterial invasion has not been established.

METHODS

HCT with a sequential cine-display was carried out in 34 patients with solid pancreatic tumors and 28 control subjects without angiographic abnormality. The HCT scans were compared with angiograms.

RESULTS

All major arteries (celiac, superior mesenteric, splenic, gastroduodenal) and superoanterior pancreaticoduodenal arteries were well demonstrated by HCT in control subjects. However, posterior pancreaticoduodenal arcades and other smaller arteries were poorly identified. Although 19 major arterial invasions were equally diagnosed by HCT and angiography in patients with pancreatic tumors, only 4 of 11 minor arterial invasions were correctly diagnosed by HCT.

CONCLUSIONS

Although HCT has some limitations in the evaluation of minor peripancreatic arteries, it can provide enough information for making a decision about conducting pancreatic surgery.

Efficacy of helical CT in T-staging of gastric cancer

PURPOSE

The purpose of this study was to evaluate the performance of helical CT in preoperative T-staging in patients with gastric cancer.

METHOD

A total of 71 patients with an established diagnosis of gastric cancer [75 lesions, 46 early (T1) and 29 advanced (T2 or more) cancers] were evaluated with helical CT. Helical CT was performed with 5-mm slice thickness at 5-mm/s table incrementation. Using the volumetric data by helical scanning, axial CT images (5-mm slice thickness at 5-mm intervals) and multiplanar reconstruction (MPR) images were obtained. CT findings were compared with histopathologic studies of the resected specimen.

RESULTS

Sensitivity of helical CT for gastric cancer was 26% (12 of 46) for early and 100% (29 of 29) for advanced cancer. Three lesions were misdiagnosed as gastric cancer by helical CT. Histopathologically, all early gastric cancers detected by helical CT were either polypoid or elevated types or showed massive invasion of the submucosal layer. The differentiation between T1 cancer with massive submucosal invasion and advanced cancer was difficult. The differentiation between T2 and T3 cancer was possible in 73% (19 of 26) and between T1/T2 and T3/T4 (extraserosal invasion) in 83% (34 of 41). Overall T-staging was correct in 66% (27 of 41). MPR images improved the detection rate (three lesions) or increased confidence in T-staging (eight lesions) over axial CT images.

CONCLUSION

When helical CT detected gastric cancer that was not a polypoid or elevated type with underlying normal-appearing gastric wall, it was either T1 cancer with massive invasion of the cancer cells into the submucosal layer or advanced cancer. However, differentiation between these two stages was difficult on CT. Diagnosis of serosal invasion was not markedly improved by helical CT. MPR images increased confidence in the staging of certain gastric cancers, such as those in locations where CT images are susceptible to partial volume averaging effects.

MR imaging of focal nodular hyperplasia of the liver: value of contrast-enhanced dynamic study

To clarify the role of MR imaging of hepatic focal nodular hyperplasia (FNH), MR images of 11 patients with 13 FNH were retrospectively reviewed. MR imaging with T1- and T2-weighted spin echo sequences was performed for all lesions. Dynamic studies using the SPGR technique followed by postcontrast delayed T1-weighted images were performed in four patients with five lesions. Gd-DTPA enhanced T1-weighted images were obtained in five patients with six lesions. Two patients with single lesions received no contrast agent. The signal intensity, morphologic appearance, and enhancement patterns were evaluated. Dynamic MR study revealed homogeneous early vigorous enhancement and prolonged enhancement in all five lesions. On T1-weighted images, three lesions were hypointense, six were isointense, and four were hyperintense to the surrounding hepatic parenchyma. On T2-weighted images, four lesions were isointense and nine were hyperintense. A central scar was identified in eight lesions and showed delayed enhancement. It is concluded that dynamic MR studies are mandatory for diagnosing FNH.

Isologous diversification: a theory of cell differentiation

An isologous diversification theory for cell differentiation is processed, based on simulations of interacting cells with biochemical networks and the cell division process following consumption of some chemicals. According to the simulations of the interaction-based dynamical systems model, the following scenario of the cell differentiation is proposed. (1) Up to some threshold number, divisions bring about almost identical cells with synchronized biochemical oscillations. (2) As the number is increased, the oscillations lose synchrony, leading to groups of cells with different phases of oscillations. (3) Amplitudes of oscillation and averaged chemical compositions start to differ by groups of cells. The differentiated behavior of states is transmitted to daughter cells. (4) Recursivity is formed so that the daughter cells keep the identical chemical character. This "memory" is made possible through the transfer of initial conditions. (5) Successive differentiation proceeds. The mechanism of tumor cell formation, origin of stem cells, anomalous differentiation by transplantations, apoptosis and other features of cell differentiation process are also discussed, with some novel predictions.

MR signal intensity changes in hepatic parenchyma with ductal dilation caused by intrahepatic cholangiocarcinoma

MR images of the liver in 13 patients with surgically proven intrahepatic cholangiocarcinoma were reviewed retrospectively and correlated to the histologic analysis of surgical specimens. We paid special attention to the peripheral liver tissue with ductal dilation but without tumorous involvement. High signal intensity was observed in the hepatic parenchyma with ductal dilation on T1-weighted spin-echo images (8 of 12) and spoiled gradient-recalled echo images (seven of seven), as compared with the contralateral hepatic lobe without duct dilation. The high signal intensity was not suppressed with fat saturation and showed enhancement after administration of contrast (11 of 12). Concurrent portal venous obstruction did not have significant effect on these findings (P < .05). Correlation with pathologic specimens suggested that this enhancement was associated with periportal fibrosis. The etiology of the high signal intensity on unenhanced spin echo or gradient-recalled T1-weighted image remains unclear. Radiologists should recognize these findings and should distinguish these from tumor involvement or the arterial buffer response caused by portal venous obstruction.

Splenectomy in biliary atresia patients with recurrent jaundice following partial splenic embolization

Splenectomy was performed for three patients with biliary atresia because of re-exacerbation of their jaundice following treatment by partial splenic embolization (PSE). The subjects' red blood cell count and hemoglobin, serum level of hepatic enzymes (glutamic oxaloacetic transaminase, glutamic pyruvic transaminase, gamma-glutamyl transpeptidase, alkaline phosphatase, and lactic dehydrogenase), and total bilirubin (TB) were evaluated both before and after splenectomy in order to analyze the effects of splenectomy on these patients. The TB decreased significantly within 3 months after splenectomy in all three patients (13.0 +/- 1.6 mg/100 ml to 5.4 +/- 0.3 mg/100 ml, p < 0.05). The red blood cell count and hemoglobin increased gradually. There was a statistically significant correlation between the TB and the red blood cell count, and/or concentration of hemoglobin. The hepatic enzymes after splenectomy were not significantly different from those before splenectomy. The change in TB following splenectomy was essentially similar to that following PSE. These results suggested that the postoperative improvement in jaundice following splenectomy may not be due to improved hepatic function but merely a reflection of decreased red blood cell turnover. Splenectomy is a useful palliative procedure for jaundice in patients with biliary atresia for whom PSE is no longer effective.

Heterocyclic analogues of quinone methide: preparation and cytotoxicity of 3-oxo-3H-pyrazolo[1,5-a]indole derivatives

A series of 3-oxo-3H-pyrazolo[1,5-a]indole derivatives was prepared and characterized as heterocyclic analogues of quinone methide. These compounds showed some cytotoxicity to cancer cells, but were ineffective in an in vivo test against murine leukemia L1210.

MR imaging of hepatocellular carcinomas: effect of Cu and Fe contents on signal intensity

BACKGROUND

To elucidate the metallic factors contributing to the signal intensities of hepatocellular carcinoma (HCC) on T1-weighted magnetic resonance (MR) images and to determine whether or not changes in signal intensity contribute to the diagnosis of histological grading of HCC.

METHODS

In 35 patients immediately after surgery, the quantities of water, lipid, copper (Cu), iron (Fe), and manganese (Mn) were determined in HCCs and the surrounding hepatic parenchyma. The correlations among these findings, the histopathological findings, and the signal intensities of T1-weighted MR images were evaluated.

RESULTS

Among the 35 HCCs, 12 (34%) were of high intensity, 14 (40%) were isointense, and 9 (26%) were of low intensity on T1-weighted images versus the surrounding hepatic parenchyma. The paramagnetic ions, which contributed to the signal intensity patterns, were assumed to be Cu in HCCs (30.5 +/- 52.9 microg/g ww), and Fe in the livers (106.2 +/- 86.8 microg/g ww) and HCCs (87.7 +/- 49.1 microg/g ww). In 12 HCCs with high intensity, one was grade I, eight were grade II, and three were grade III according to Edmondson-Steiner's histopathological classification.

CONCLUSIONS

Signal intensity and signal intensity patterns alone cannot be signs of low-grade malignancy because of the Fe in livers and in HCCs.

Continuous brachial plexus infusion of butorphanol-mepivacaine mixtures for analgesia after upper extremity surgery

We have recently reported that continuous administration of butorphanol into the brachial plexus neurovascular sheath provided superior analgesia compared with that obtained with continuous i.v. administration. Furthermore, we found that analgesia was most pronounced when a mixture of mepivacaine and butorphanol was given and that butorphanol alone ranked next. In this study, we increased the dose of butorphanol, compared with that used in our previous reports, and an initial bolus dose of butorphanol was administered into the brachial plexus neurovascular sheath just after surgery had ended. Thereafter, postoperative pain relief was estimated. In patients undergoing upper extremity surgery with continuous axillary brachial plexus block, group A received a bolus of 1 ml of physiological saline with 1.5% mepivacaine, 10 ml into the brachial plexus sheath followed by a continuous brachial plexus infusion of 0.5% mepivacaine with butorphanol 6 mg at a rate of 144 ml/ 72 h. Group B was given a bolus of butorphanol 1 mg (1 ml) with 1.5% mepivacaine, 10 ml into the brachial plexus sheath and a continuous brachial plexus infusion of 0.5% mepivacaine with butorphanol 6 mg at a rate of 144 ml/72 h. After operation, VAS scores did not differ between the two groups. The time to first use of supplementary analgesia did not differ significantly between the two groups and there were no significant differences in the number of patients who required supplementary analgesia. These results indicate that continuous butorphanol 2 mg day-1 with 0.5% mepivacaine provided sufficient postoperative analgesia after upper limb surgery.

The effect of current direction induced by transcranial magnetic stimulation on the corticospinal excitability in human brain

Evoked spinal cord potentials (ESCPs) from the cervical epidural space and motor evoked potentials (MEPs) from the hand muscles were recorded simultaneously in 6 subjects following transcranial magnetic stimulation in two different coil orientations on motor cortex. The onset latency of the MEPs was approximately 1 ms shorter when the induced current flowed in a latero-medial direction (L-M stimulation) on the motor cortex as compared to a postero-anterior direction (P-A stimulation). Hence, L-M stimulation elicited an earlier component of the ESCPs than that induced by P-A stimulation. During general anesthesia with Sevoflurane, only the first component of the ESCPs could be elicited routinely following L-M stimulation. In contrast, all components of the ESCPs were dramatically attenuated following P-A stimulation. Moreover, first component latency of the ESCPs induced by L-M stimulation was almost the same as that induced by transcranial anodal electrical stimulation. These results suggest that if the induced current following transcranial magnetic stimulation flows in a latero-medial direction on motor cortex, it preferentially stimulates the corticospinal tract non-synaptically (producing a D-wave). However, if the induced current flows in a postero-anterior direction, it preferentially stimulates the corticospinal tract trans-synaptically (producing I-waves). Therefore, the direction of magnetically induced current is crucial in determining corticospinal excitability in the human brain.