SPOP is essential for DNA replication licensing through maintaining translation of CDT1 and CDC6 in HaCaT cells

Speckle-type pox virus and zinc finger (POZ) protein (SPOP), a substrate recognition receptor for the cullin-3/RING ubiquitin E3 complex, leads to the ubiquitination of >40 of its target substrates. Since a variety of point mutations in the substrate-binding domain of SPOP have been identified in cancers, including prostate and endometrial cancers, the pathological roles of those cancer-associated SPOP mutants have been extensively elucidated. In this study, we evaluated the cellular functions of wild-type SPOP in non-cancerous human keratinocyte-derived HaCaT cells expressing wild-type SPOP gene. SPOP knockdown using siRNA in HaCaT cells dramatically reduced cell growth and arrested their cell cycles at G1/S phase. The expression of DNA replication licensing factors CDT1 and CDC6 in HaCaT cells drastically decreased on SPOP knockdown as their translation was inhibited. CDT1 and CDC6 downregulation induced p21 expression without p53 activation. Our results suggest that SPOP is essential for DNA replication licensing in non-cancerous keratinocyte HaCaT cells.

The clock gene cryptochrome of Bactrocera cucurbitae (Diptera: Tephritidae) in strains with different mating times

Differences in mating time between populations can give rise to premating reproductive isolation. Tephritid fruit flies exhibit large variation in mating time among intra- or inter-specific populations. We previously cloned the clock gene period from two strains of melon fly, Bactrocera cucurbitae; in one the individuals mate early during the day, whereas in the other the individuals mate later. These strains were originally established by divergent artificial selection for developmental time, 'short' and 'long', with early and late mating times, respectively. The deduced amino acid sequences of PERIOD proteins for these two strains were reported to be identical. Here we cloned another clock gene cryptochrome (cry) from the two strains, and found two stable amino acid substitutions in the strains. In addition, the allele frequency at the two polymorphic sites of cry gene correlated with the circadian locomotor period (tau) across strains, whereas the expression pattern of cry mRNA in the heads of flies taken from the short strain significantly differed from that from the long strain. These findings suggest that variation in the cry gene is related to differences in the circadian behaviour in the two strains, thus implying that the cry gene may have an important role in reproductive isolation.

A computer-aided temporal and dynamic subtraction technique of the liver for detection of small hepatocellular carcinomas on abdominal CT images

It is often difficult for radiologists to identify small hepatocellular carcinomas (HCCs) due to insufficient contrast enhancement. Therefore, we have developed a new computer-aided temporal and dynamic subtraction technique to enhance small HCCs, after automatically selecting images set at the same anatomical position from the present (non-enhanced and arterial-phase CT images) and previous images. The present study was performed with CT images from 14 subjects. First, we used template-matching based on similarities in liver shape between the present (non-enhanced and arterial-phase CT images) and previous arterial-phase CT images at the same position. Temporal subtraction images were then obtained by subtraction of the previous image from the present image taken at the same position of the liver. Dynamic subtraction images were also obtained by subtraction of non-enhanced CT images from arterial-phase CT images taken at the same position of the liver. Twenty-one of 22 nodules (95.5%) with contrast enhancement were visualized in temporal and dynamic subtraction images. Compared with present arterial-phase CT images, increases of 150% and 140% in nodule-to-liver contrast were observed on dynamic and temporal subtraction images, respectively. These subtraction images may be useful as reference images in the detection of small moderately differentiated HCCs.

[Three-dimensional image of Adamkiewicz artery detected by using multidetector CT: preoperative assessment of thoraco-abdominal aortic aneurysm]

Images were obtained with the following parameter 0.5 sec/r, 1 mm collimation, pitch 3.5, 120 kV, 300 mA. One hundred ml of contrast material containing 350 mg I/ml was injected with a power injector (dual shot type) into an antecubital vein at a rate of 3.5 ml/sec (70 ml). Then remaining 30 ml and same volume of saline were infused at a rate of 1.5 ml/sec simultaneously. Twenty-five seconds after the injection, scan was performed from the level of L2 to T5 vertebrae. Transverse sections were reconstructed with a 1 mm thickness at 0.7 mm intervals. Imaging was done with multiplanar and curved planar reformations. In case of vertebral deformity, however, 3D images were made to depict the Adamkiewicz artery. In 141 patients, 107 (76%) Adamkiewicz arteries from the interverbral foramen to the hairpin-shaped union with the anterior spinal artery were visualized. Seventy-nine arteries of Adamkiewicz (73%) originated from the left side. Our method is useful for depicting Adamkiewicz artery.

Benidipine, a long-acting Ca channel blocker, limits infarct size via bradykinin- and NO-dependent mechanisms in canine hearts

Amlodipine increases NO levels in coronary vessels and aorta via bradykinin-dependent mechanisms in vitro. We have previously reported that a long-acting Ca channel blocker, benidipine, increases cardiac NO levels in ischemic canine hearts, suggesting that benidipine may also protect against ischemia and reperfusion injury via bradykinin- and NO-dependent mechanisms. We examined this possibility. In open chest dogs, the left anterior descending coronary artery was perfused with blood through a bypass tube and was occluded for 90 min followed by 6 hours of reperfusion. Infarct size was assessed by TTC staining at 6 hours of reperfusion. When benidipine doses of 50, 100, and 200 ng/kg/min were infused via the bypass tube between 10 min prior to the onset of ischemia and after 60 min of reperfusion, systemic blood pressure did not change significantly. Infarct size decreased with the administration of benidipine (50, 100, and 200 ng/kg/min) when compared to the untreated condition (24.8+/-2.5, 17.3+/-3.1, and 16.5+/-2.0 vs. 43.4+/-5.6%, respectively) associated with the increased release of NO and bradykinin in the coronary venous blood upon reperfusion. Myeloperoxidase activity of the myocardium increased after 6 hours of reperfusion, which was attenuated by benidipine. The limitation of infarct size and the increase in myeloperoxidase activity were completely blunted by either L-NAME or HOE140. There were no significant differences in collateral blood flow assessed by the microsphere method after 45 min of ischemia for any of the groups. Thus, we conclude that the Ca channel blocker, benidipine, limits infarct size via bradykinin- and NO-dependent mechanisms.

Characteristics of acoustic noise in echo-planar imaging

Characteristics of the acoustic noise generated by magnetic resonance imagers of different systems and performance levels were studied when operating in echo-planar imaging (EPI) sequence. Continuous equivalent A-weighted sound pressure levels (Leq) and peak impulse sound pressure levels (Lpeak) during EPI were measured in 12 clinical super-conducting MRI systems (0.5-1.5 T). Sound pressure levels and frequency spectra of EPI were compared with those of nine different pulse sequences. EPI sound pressure levels differed among institutions (Leq = 94.2 +/- 2.7 dBA. Lpeak = 109.1 +/- 3.5 dB), but these were within permissible noise exposure levels. Sound pressure levels during EPI were not significantly different from those during other pulse sequences. However, compared to other pulse sequences. EPI had a significantly greater proportion of acoustic noise in the high octave-frequency band. Single-shot EPI had relatively higher frequency noise and greater Leq than multishot EPI, but the difference in Leq decreased when the number of slices in multishot EPI was increased.

Nifedipine limits infarct size via NO-dependent mechanisms in dogs

OBJECTIVES

Amlodipine increases NO levels in coronary vessels and aorta via bradykinin-dependent mechanisms in vitro. We have previously reported that nifedipine increases cardiac NO levels in the ischemic canine hearts, suggesting that nifedipine may also have protective effects against ischemia and reperfusion injury, because the enhancement of NO production limits infarct size. We tested whether nifedipine limits infarct size via NO-dependent mechanisms.

METHODS

In open chest dogs, the left anterior descending coronary artery was perfused with blood through a bypass tube and occluded for 90 min followed by 6 hours of reperfusion. Infarct size was assessed at 6 hours of reperfusion. Nifedipine of 3 or 6 microg/kg/min was infused into the bypass tube between 10 min prior to the onset of ischemia and 60 min of reperfusion.

RESULTS

Neither systemic blood pressure nor heart rate changed during infusion of nifedipine. Infarct size was reduced by the administration of nifedipine (3 or 6 microg/kg/min) compared with the untreated condition (25.6+/-2.6 and 19.1+/-3.5 vs. 43.4+/-5.6%, respectively), which was completely blunted by L-NAME (45.0+/-3.6 and 45.4+/-4.2 vs. 47.9+/-3.9% in the nifedipine (3 or 6 microg/kg/min) with L-NAME groups vs. the L-NAME group). Myeloperoxidase activity of the myocardium increased after 6 hours of reperfusion, which was attenuated by nifedipine. The limitation of infarct size and the attenuation in myeloperoxidase actiivity were completely blunted by L-NAME. There were no significant differences in collateral blood flow at 45 min of ischemia between each group.

CONCLUSIONS

We conclude that the Ca channel blocker, nifedipine, limits infarct size via NO-dependent mechanisms.

Differential subcellular actions of ACE inhibitors and AT(1) receptor antagonists on cardiac remodeling induced by chronic inhibition of NO synthesis in rats

Chronic inhibition of NO synthesis induces cardiac hypertrophy independent of systemic blood pressure (SBP) by increasing protein synthesis in vivo. We examined whether ACE inhibitors (ACEIs) enalapril and temocapril and angiotensin II type-I receptor antagonists (angiotensin receptor blockers [ARBs]) losartan and CS-866 can block cardiac hypertrophy and whether changes in activation of 70-kDa S6 kinase (p70S6K) or extracellular signal-regulated protein kinase (ERK) are involved. The following 13 groups were studied: untreated Wistar-Kyoto rats and rats treated with NO synthase inhibitor Nomega-nitro-L-arginine methyl ester (L-NAME), D-NAME (the inactive isomer of L-NAME), L-NAME plus hydralazine, L-NAME plus enalapril (3 mg. kg(-1). d(-1)) or temocapril (1 or 10 mg. kg(-1). d(-1)), L-NAME plus losartan (10 mg. kg(-1). d(-1)) or CS-866 (1 or 10 mg. kg(-1). d(-1)), L-NAME plus temocapril-CS866 in combination (1 or 10 mg. kg(-1). d(-1)), and L-NAME plus rapamycin (0.5 mg. kg(-1). d(-1)). After 8 weeks of each experiment, ratios of coronary wall to lumen (wall/lumen) and left ventricular weight to body weight (LVW/BW) were quantified. L-NAME increased SBP, wall/lumen, and LVW/BW compared with that of control. ACEIs, ARBs, and hydralazine equally canceled the increase in SBP induced by L-NAME. However, ACEIs and ARBs equally (but not hydralazine) attenuated increase in wall/lumen and LVW/BW induced by L-NAME. The L-NAME group showed both p70S6K and ERK activation in myocardium (2.2-fold and 1.8-fold versus control, respectively). ACEIs inactivated p70S6K and ARBs inactivated ERK in myocardium, but hydralazine did not change activation of either kinase. Thus, ACEIs and ARBs modulate different intracellular signaling pathways, inhibiting p70S6K or ERK, respectively, to elicit equal reduction of cardiac hypertrophy induced by chronic inhibition of NO synthesis in vivo.

Role of cellular acidosis in production of nitric oxide in canine ischemic myocardium

We tested the hypothesis that cellular acidosis modulates the production of nitric oxide (NO) in ischemic hearts. In canine hearts, we decreased coronary blood flow (CBF) to one third of the control by reduction of coronary perfusion pressure (105+/-3 to 41+/-5 mmHg), and thereafter we maintained CBF constant (89.8+/-1.6 to 30.0+/-0.5 ml/100 g/min) with an intracoronary administration of either saline, atropine, rauwolscine, HOE140, 8-sulfophenyltheophylline (8SPT), NaHCO3, or HOE642 (the inhibitor of Na+/H+ exchange). The cardiac NO levels defined as the differences of the nitrate and nitrite levels between coronary venous and arterial blood increased in the saline administration (2.9+/-0.2 to 12.7+/-1.7 micromol/l), and the extents of increases were identical in the condition of either saline, atropine, rauwolscine, HOE140 or 8SPT administration. In the condition with either NaHCO3 or HOE642, the increases in the cardiac NO levels were blunted (4.5+/-0.7 and 4.8+/-0.4 micromol/l, respectively). Cyclic GMP content of epicardial coronary artery in the ischemic area increased, which was also attenuated by either NaHCO3 or HOE642. We confirmed the acidosis-induced NO production in a more severe ischemic myocardium, and also showed that cellular acidosis produced by infusion of HCl increased NO production in non-ischemic myocardium. We conclude that cellular acidosis and subsequent activation of Na+/H+ exchanges modulate production of endogenous NO in canine ischemic myocardium.

Cardioprotective effect afforded by transient exposure to phosphodiesterase III inhibitors: the role of protein kinase A and p38 mitogen-activated protein kinase

BACKGROUND

Phosphodiesterase III inhibitors (PDEIII-Is) improve the hemodynamic status of heart failure via inotropic/vasodilatory effects attributable to the increase in intracellular cAMP level. Direct cardioprotection by PDEIII-Is and its underlying mechanisms, however, have not been identified. We tested the infarct size-limiting effect of PDEIII-Is and the roles of cAMP, protein kinase (PK) A, PKC, and mitogen-activated protein kinase (MAPK) families in open-chest dogs. Methods and Results-- Milrinone, olprinone (PDEIII-Is), or dibutyryl-cAMP (db-cAMP) was injected intravenously 30 minutes before 90-minute ischemia, followed by 6 hours of reperfusion. Olprinone was also examined with an intracoronary cotreatment with a PKA inhibitor (H89), a PKC inhibitor (GF109203X), an extracellular signal-regulated kinase kinase (MEK) inhibitor (PD98059), or a p38 MAPK inhibitor (SB203580) throughout the preischemic period. Either PDEIII-Is or db-cAMP caused substantial hemodynamic changes, which returned to control levels in 30 minutes. Collateral flow and percent risk area were identical for all groups. Both PDEIII-Is and db-cAMP increased myocardial p38 MAPK activity during the preischemic period, which was blocked by H89, but not by GF109203X. Both PDEIII-Is and db-cAMP reduced infarct size (19.1+/-4.1%, 17.5+/-3.3%, and 20.3+/-4.8%, respectively, versus 36.1+/-6.2% control, P<0.05 each). Furthermore, the effect of olprinone was blunted by either H89 (35.5+/-6.4%) or SB203580 (32.6+/-5.9%), but not by GF109203X or PD98059. H89, GF109203X, PD98059, or SB203580 alone did not influence infarct size.

CONCLUSIONS

Pretreatment with PDEIII-Is has cardioprotective effects via cAMP-, PKA-, and p38 MAPK-dependent but PKC-independent mechanisms in canine hearts.

[Giant epidermal cyst in the perineum extending into the pelvic space in the patient with polycystic kidney disease: a case report]

A 75-year-old man with autosomal dominant polycystic kidney disease was admitted to our hospital with the chief complaint of a giant mass in the left side of the perineum that had gradually developed in size during the previous 20 years. Palpation revealed a neonatal head-sized cystic mass with no tenderness. Magnetic resonance imaging (MRI) demonstrated a well-circumscribed homogeneous mass extended to the dorsal side of the bladder. It was excised surgically without any injury of rectum or urinary tract. The resected specimen was 23 x 18 x 12 cm in size and 1.2 kg in weight. The pathological diagnosis was epidermal cyst. Cases with an epidermal cyst extending into the pelvic space are extremely rare with few cases having been reported in the world.

[Clinical outcome of potassium-titanyl-phosphate (KTP/532) laser vaporization prostatectomy for benign prostate hyperplasia]

OBJECTIVE

To study the feasibility of vaporization prostatectomy by potassium-titanyl-phosphate (KTP/532) laser in men with bladder outlet obstruction due to benign prostatic hyperplasia (BPH) and to evaluate their clinical and voiding outcome 2 weeks and 6 months after operation.

PATIENTS AND METHODS

Laser vaporization prostatectomy with the KTP/532 laser at 20 W was performed in 21 BPH patients varying from 56 to 75 years of age. All cases were performed under the spinal anesthesia. The laser was produced by MODEL SL20/50 and ADD/Stat side-firing fibers were used. A urethral catheter was inserted post-operatively and was removed within 6 days after operation. The hemoglobin value was examined on the first day after operation and uroflowmetry was executed 2 weeks and 6 months after operation with the examination of the residual urine volume. IPSS and QOL score were recorded by patients 2 weeks and 6 months after operation.

RESULTS

The prostate volumes ranged from 22 to 52 mL (mean 37.3 +/- 10.4). None of the 21 patients had any significant blood loss or any fluid absorption. The voiding parameters improved: mean peak flow rate increased from 7.1 to 16.5 mL/s 2 weeks after operation and to 15.2 mL/s 6 months after operation and residual volume decreased from 172 to 45 mL 2 weeks after operation and to 43 mL 6 months after operation. IPSS and QOL score improved significantly in Wilcoxon signed-ranks test. The ratio of excellent and good in efficacy criteria of Kawabe group was 71.4% 2 weeks after operation and that was 71.4% 6 months after operation. Mean catheterization term was 4.5 days. Only one patient showed transient urinary retention when the catheter was removed the third postoperative day. None had incontinence postoperatively. No other significant complications were recognized. The prostate volume was more than 50 mL in 3 cases and the postoperative 6 months outcomes of the 3 cases were all poor in their symptoms in the efficacy criteria of Kawabe group.

CONCLUSIONS

KTP laser vaporization prostatectomy is safe and effective for obstructive prostates up to 50 mL in volume and produces good results 2 weeks post operatively that are sustained for 6 months after operation.

cDNA array hybridization reveals cardiac gene expression in acute ischemic murine hearts

PURPOSE

Although cDNA array technique has recently become available in the cardiovascular field, it has not yet been established what kind of genes in the myocardium are expressed by acute ischemia. Since many substances contribute to the pathophysiology of acute ischemic hearts, we investigated transcription responses of murine hearts to ischemia using cDNA array representing 18,376 genes.

METHODS AND RESULTS

In 29 male mice, we ligated the proximal site of the left coronary artery for 60 min. In 14 mice, we performed the sham operation without the ligation of the left coronary artery. After 60 min, the hearts were excised to obtain mRNA, and we performed cDNA array analysis. In 18,376 cDNA, 2 known genes were upregulated over 10-fold, 11 known genes were upregulated 5.0- to 9.9-fold, and 32 unknown genes were upregulated over 5.0-fold compared to sham-operated controls. In contrast, 11 known genes and 7 unknown genes were downregulated to levels below 0.2-fold. For 9 of the 13 known genes of which expression was increased as analyzed by cDNA array, subsequent Northern blot analysis also revealed an increase in expression.

CONCLUSION

Using cDNA array analysis we found that cardiac expression of 24 known and 39 unknown genes was modulated by acute ischemic stress, and appeared to be related to the pathophysiology of ischemic hearts. These results show that cDNA array analysis may provide a new molecular insight to the pathophysiology of acute ischemic hearts.

Role of phasic dynamism of p38 mitogen-activated protein kinase activation in ischemic preconditioning of the canine heart

Although ischemic stress, including ischemic preconditioning (IP), activates p38 mitogen-activated protein kinase (MAPK), the relationship between p38 MAPK activation and the underlying cellular mechanisms of cardioprotection by IP is not verified in vivo. We examined the effects of the selective p38 MAPK inhibition on the cardioprotective effect of IP in the open-chest dogs. The coronary artery was occluded 4 times for 5 minutes, separated by 5 minutes of reperfusion (IP) followed by 90 minutes of occlusion and 6 hours of reperfusion. We infused SB203580 into the coronary artery during IP and 1 hour of reperfusion, during IP alone, and during sustained ischemia in the IP group. p38 MAPK activity markedly increased during IP but did not additionally increase at the onset of ischemia and was even attenuated at 15 minutes of sustained ischemia, and heat-shock protein (HSP) 27 was phosphorylated and translocated from cytosol to myofibril or nucleus without affecting total protein level at the onset of ischemia compared with the control group. SB203580 treatment (1 micromol/L) only during IP blunted the infarct size limitation by IP (37.3+/-6.3% versus 7.4+/-2.1% in the IP group, P:<0.01) and attenuated either phosphorylation or translocation of HSP27 during IP. Although the SB203580 treatment throughout the preischemic and postischemic periods had no significant effect on infarct size (33.3+/-9.4%) in this model, treatment with SB203580 only during ischemia partially mimicked the infarct size limitation by IP (26.8+/-3.5%). Thus, transient p38 MAPK activation during ischemic preconditioning mainly mediates the cardioprotection followed by HSP27 phosphorylation and translocation in vivo in the canine heart.

Role of mitochondrial and sarcolemmal K(ATP) channels in ischemic preconditioning of the canine heart

We tested whether mitochondrial or sarcolemmal ATP-sensitive K(+) (K(ATP)) channels play a key role in ischemic preconditioning (IP) in canine hearts. In open-chest beagle dogs, the left anterior descending artery was occluded four times for 5 min each with 5-min intervals of reperfusion (IP), occluded for 90 min, and reperfused for 6 h. IP as well as cromakalim and nicorandil (nonspecific K(ATP) channel openers) markedly limited infarct size (6.3 +/- 1.2, 8.9 +/- 1.9, and 7.2 +/- 1.6%, respectively) compared with the control group (40.9 +/- 4.1%). A selective mitochondrial K(ATP) channel blocker, 5-hydroxydecanoate, partially blunted the limitation of infarct size in the animals subjected to IP and those treated with cromakalim and nicorandil (21.6 +/- 3.8, 25.1 +/- 4.6, and 19.8 +/- 5.2%, respectively). A nonspecific K(ATP) channel blocker, glibenclamide, completely abolished the effect of IP (38.5 +/- 6.2%). Intracoronary or intravenous administration of a mitochondria-selective K(ATP) channel opener, diazoxide, at >100 micromol/l could only partially decrease infarct size (19.5 +/- 4.3 and 20.1 +/- 4.4%, respectively). In conclusion, mitochondrial and sarcolemmal K(ATP) channels independently play an important role in the limitation of infarct size by IP in the canine heart.

Protein tyrosine kinase is not involved in the infarct size-limiting effect of ischemic preconditioning in canine hearts

Protein kinase C (PKC) plays an important role in ischemic preconditioning (IP). Because (1) tyrosine kinase is located at the downstream of PKC for IP in the rabbit hearts and (2) we have reported that ecto-5'-nucleotidase is the substrate for PKC and plays a crucial role for the infarct size-limiting effect, we tested whether tyrosine kinase activation contributes to either activation of ecto-5'-nucleotidase or the infarct size-limiting effect of the early phase of IP in the canine heart. In dogs, the IP procedure (4 cycles of 5-minute occlusion of coronary artery) and exposure to 12, 13-phorbol myristate acetate (PMA) each activated myocardial ecto-5'-nucleotidase and Lck tyrosine kinase. Genistein (10, 30, and 100 microg. kg(-)(1). min(-)(1) IC), an inhibitor of tyrosine kinase, attenuated the activation of Lck tyrosine kinase but did not attenuate the activation of ecto-5'-nucleotidase due to either IP or PMA. In the other canine hearts, IP attenuated infarct size (49+/-5 versus 11+/-3 or 16+/-3%, P<0.01) due to 90 minutes of coronary occlusion followed by 6 hours of reperfusion, which was not blunted by 3 or 2 (30 and 100 microg. kg(-)(1). min(-)(1)) doses of genistein (infarct sizes, 15+/-4, 13+/-4, and 13+/-3%, respectively, and 17+/-3 and 15+/-4%, respectively) or lavendustin A. Tyrosine kinase does not activate ecto-5'-nucleotidase or trigger the infarct size-limiting effect of the early phase of IP in canine hearts.

Suppression-burst patterns in intractable epilepsy with focal cortical dysplasia

We report on a patient with early-onset spasms in series and partial seizures associated with focal cortical dysplasia whose EEGs showed suppression-burst patterns during early infancy. These electroclinical characteristics suggested a diagnosis of Ohtahara syndrome, but the EEG findings were atypical because of the lack of suppression-burst patterns during wakefulness. In addition, the patient did not have severe psychomotor retardation. With high-dose pyridoxal phosphate therapy, seizures were suppressed and suppression-burst patterns disappeared at 2 months of age. Focal motor seizures recurred later and they often evolved into epilepsia partialis continua. Patients with early-onset intractable seizures associated with suppression-burst patterns on EEGs have several different etiologies, and these patients should be categorized according to their etiology in addition to their syndromic diagnosis.

[Multicentric Castleman's disease found by a renal sinus lesion: a case report]

A 79-year-old man complained of anorexia and weight loss. Computed tomography and magnetic resonance imaging showed a solitary mass in the left renal sinus. Left nephrectomy was carried out under a clinical diagnosis of renal pelvic tumor. The pathological diagnosis was plasma cell type of Castleman's disease. The patient suffered from lymph node swelling in the right neck at age 75 and the lymph node was resected. The pathological diagnosis was lymphadenitis but it proved to be plasma cell type of Castleman's disease. The patient also had had a lymphadenectomy in the supraclavicular fossa and in the supraorbital area at age 76. Both had been diagnosed as lymphadenitis pathologically but they proved to be plasma cell type of Castleman's disease. The final diagnosis was multicentric Castleman's disease. We reviewed multicentric Castleman's disease.

Nifedipine-induced coronary vasodilation in ischemic hearts is attributable to bradykinin- and NO-dependent mechanisms in dogs

BACKGROUND

Dihydropyridine calcium channel blockers protect endothelial cells against ischemia and reperfusion injury, suggesting that nifedipine may increase the in vivo cardiac NO level and thus coronary blood flow (CBF) in ischemic hearts. We tested this hypothesis.

METHODS AND RESULTS

In open-chest dogs, coronary perfusion pressure (CPP) was reduced in the left anterior descending coronary artery so that CBF decreased to one third of the control level, and thereafter CPP was maintained constant (103+/-8 to 43+/-3 mm Hg, n=9). We obtained fractional shortening (FS) and lactate extraction ratio (LER) as indices of regional myocardial contraction and metabolism. Both FS (26.4+/-2.1% to 6.7+/-2.0%, n=9, P<0.001) and LER (32+/-6% to -37+/-5%, n=9, P<0.001) showed a decrease when CPP was reduced. After intracoronary infusion of nifedipine (4 microgram. kg(-1). min(-1)), CBF increased from 30+/-1 to 48+/-4 mL. 100 g(-1). min(-1) (P<0.01) without a change of CPP (n=9). Both FS (14.0+/-1.9%, n=9) and LER (-9+/-7%, n=9) also increased (P<0.01). Nifedipine increased the difference in the level of metabolites of NO (nitrate+nitrite; 9+/-3 to 25+/-5 nmol/mL, n=9, P<0.01) and bradykinin (22+/-5 to 58+/-4 pmol/mL, n=9, P<0.01) between coronary venous and arterial blood. L-NAME (an NO synthase inhibitor) or HOE-140 (a bradykinin receptor antagonist) attenuated (P<0.05) the increase in CBF (29+/-3 and 35+/-2 mL. 100 g(-1). min(-1), n=5 each), FS (4.8+/-0.6% and 6.9+/-1.7%, n=5 each), LER (-47+/-8% and -35+/-9%, n=5 each), and nitrate+nitrite (3+/-2 and 8+/-4 nmol/mL, n=5 each) due to nifedipine infusion.

CONCLUSIONS

These results indicate that the calcium channel blocker nifedipine mediates coronary vasodilation and improves myocardial ischemia through both bradykinin/NO-dependent and -independent mechanisms.

New tissue substitutes representing cortical bone and adipose tissue in quantitative radiology

To employ quantitative radiology more accurately, we examined phantom materials for cortical bone and adipose tissue as calibration standards and as experimental phantoms. New tissue substitutes for cortical bone and adipose tissue composed of liquid phantom were verified by computing their attenuation coefficients and observing their chemical properties. We showed that a potassium pyrophosphate (K4P2O7) solution for cortical bone was comparable to a dipotassium hydrogen phosphate (K2HPO4) solution. Also, the use of methyl alcohol for adipose tissue was more suitable than ethyl alcohol as a phantom material because of its physical and chemical properties.

Relationship between the biodistributions of radioactive metal nuclides in tumor tissue and the physicochemical properties of these metal ions

This study was undertaken to elucidate the relationship between the biodistribution of radioactive metal nuclides in tumor tissue and its physicochemical properties. Potassium analogs (86Rb, 134Cs, 201Tl) were taken up into viable tumor tissue, although 22Na concentrated in necrotic tumor tissue. 67Ga and 111In were more predominant in inflammatory tissue than in the viable and necrotic tumor tissue. 169Yb and 167Tm accumulated in viable tumor tissue and tissue containing viable and necrotic tumor tissue. 67Ga, 111In, 169Yb and 167Tm were bound to the acid mucopolysaccharide with a mol. wt. of about 10,000 daltons in the tumor tissue. 46Sc, 51Cr, 95Zr, 181Hf, 95Nb, 182Ta, and 103Ru were highly concentrated in inflammatory tissue and were bound to the acid mucopolysaccharides with a mol. wt. exceeding 40,000 daltons. 65Zn and 103Pd concentrated in viable tumor tissue and were bound to the protein in the tissue. The results suggest that the difference in intra-tumor distribution of these elements is caused by a difference in the binding substances (or status) of these elements in the tissues, and the binding substance is determined by physicochemical properties of the elements. We therefore conclude that the biodistribution of radioactive metal ions in tumor tissue is determined by its own physicochemical properties.

Dispersion of signal-averaged P wave duration on precordial body surface in patients with paroxysmal atrial fibrillation

AIMS

This study sought to investigate whether the spatial dispersion of signal-averaged P wave duration would be increased in patients with paroxysmal atrial fibrillation, by use of precordial mapping of the P wave signal-averaged ECG.

METHODS AND RESULTS

The P wave signal-averaged ECG was recorded by the P wave-triggering method from 16 precordial leads in 55 patients with paroxysmal atrial fibrillation and 57 control subjects. As an index of the dispersion of signal-averaged P wave duration, we obtained the difference between the maximum and minimum in 16 recording sites. The dispersion was significantly greater in the patients with paroxysmal atrial fibrillation than the controls (26.6 +/- 9.5 vs 14.8 +/- 6.7 ms, P<0.0001). In 25 patients with symptomatic attacks of paroxysmal atrial fibrillation, the signal-averaged ECG was repeated 1 h after a single dose of orally administered pilsicainide, a new class Ic drug. These patients were prospectively followed-up for 10 +/- 11 months with pilsicainide. The rate of freedom from recurrence of paroxysmal atrial fibrillation attacks was significantly (P<0.0001) higher in patients with whom dispersion was decreased by the single dose (54%[7/13]) than in those in whom dispersion increased (8%[1/12]).

CONCLUSION

Increased dispersion of signal-averaged P wave duration would play an important role in generating paroxysmal atrial fibrillation and would be useful in the prediction of drug efficacy to evaluate the change in dispersion by a single administration of pilsicainide.

[Computer-aided diagnosis in the detection of temporal changes in sequential chest radiographs]

To aid radiologists in the diagnosis of screening chest radiographs, a temporal subtraction technique using digital image processing was developed. The accurate image registration of two sequential images enables us to detect even subtle changes in the "difference image" between them. In this report, a new method based on matching "lung markings" is introduced. Twenty-nine pairs of sequential posteroanterior chest radiographs with and without temporal changes were selected from cases examined with the computed radiography system. Image registration was employed, with the local matching of "lung markings" in previous and current radiographs. Observer performance tests were carried out by eight radiologists, with and without the "difference image." Observer performance tests with the temporal subtraction image showed that six of eight observers diagnosed them with higher sensitivity (mean, 43.9% vs. 55.3%) and a comparable false positive response. Mean area under the AFROC (alternative free-response receiver operating characteristics) curve also improved from 0.596 to 0.647, a statistically significant difference. The subtraction image using this registration technique improved diagnostic accuracy for subtle temporal changes.

Increased expression of P-selectin on platelets is a risk factor for silent cerebral infarction in patients with atrial fibrillation: role of nitric oxide

BACKGROUND

Platelet activation and decreased levels of nitrite and nitrate (NOx), stable end products of nitric oxide (NO), are reported in patients with atrial fibrillation (AF). We examined the time-course changes in plasma NOx levels and the expression of P-selectin on platelets after the onset of AF in a canine model and determined whether these parameters could be risk factors for silent cerebral infarction in patients with AF.

METHODS AND RESULTS

AF was induced by rapid atrial pacing in the canine model of AF. Plasma NOx levels were significantly decreased and the levels of P-selectin on platelets and of neutrophil/platelet conjugates were significantly increased after the onset of AF in this model. The in vitro experiments demonstrated that the inhibition of NO synthesis increased the expression of P-selectin on platelets. Plasma NOx levels (19.7+/-2.4 versus 27.5+/-2.8 micromol/L) were significantly lower in 25 patients with AF compared with age- (+/-2 years) and sex-matched control subjects. Conversely, the levels of P-selectin on platelets (7.6+/-0.8% versus 4.8+/-0.7%) and of neutrophil/platelet conjugates (14.8+/-0.9% versus 8.1+/-0.6%) were significantly higher in patients with AF. Multiple regression analysis revealed that increased P-selectin on platelets and advanced age were associated with the number of foci of silent cerebral infarction.

CONCLUSIONS

An irregular heart rate that is characteristic of AF appeared to blunt NO synthesis. The increased expression of P-selectin on platelets associated with the reduced NO levels was a risk factor for silent cerebral infarction in patients with AF.

Prediction of the effectiveness of long-term beta blocker treatment for dilated cardiomyopathy by signal averaged electrocardiography

OBJECTIVE

To determine whether the effectiveness of long-term beta blocker treatment for idiopathic dilated cardiomyopathy can be predicted by signal averaged electrocardiography (ECG).

PATIENTS

31 patients with dilated cardiomyopathy and without bundle branch block were included in a retrospective study and 16 in a prospective study.

METHODS

A signal averaged ECG was recorded before beta blocker treatment, and three variables were measured from the vector magnitude: QRS duration, root mean square voltage for the last 40 ms (RMS40), and duration of the terminal low amplitude signals (< 40 microV) (LAS40). In the retrospective study, these variables were compared among good responders (showing > or = 0.10 increase in ejection fraction 12 months after start of beta blocker treatment) and poor responders without such improvement. The validity of the signal averaged ECG criteria for prediction of the response to beta blocker treatment was examined in the prospective study.

RESULTS

In the retrospective study, good responders (n = 16) had a shorter QRS duration (mean (SD): 122.9 (11) v 138 (14.4) ms, p < 0.005) and LAS40 (33.1 (8.9) v 42.5 (7.8) ms, p < 0.005), and a higher RMS40 (31.6 (16.3) v 19.0 (10.3) microV, p < 0.02) than poor responders (n = 15). Signal averaged ECG criteria for good response were defined as two or more of the following: QRS duration < 130 ms, RMS40 > 20 microV, LAS40 < 40 ms (sensitivity 81%, specificity 73%). In the prospective study, six of seven patients who met these criteria showed a good response to the beta blocker treatment, while eight of nine who did not showed a poor response (chi 2 = 6.1, p < 0.02). The signal averaged ECG criteria gave a sensitivity of 86% and a specificity of 89% for predicting the effectiveness of beta blocker treatment.

CONCLUSIONS

A signal averaged ECG might be useful in predicting the effectiveness of beta blocker treatment for dilated cardiomyopathy.

Prediction of transition to chronic atrial fibrillation in patients with paroxysmal atrial fibrillation by signal-averaged electrocardiography: a prospective study

BACKGROUND

It is well known that paroxysmal atrial fibrillation (PAF) often precedes the establishment of chronic atrial fibrillation (CAF). However, there have been no definite methods to predict the transition from PAF to CAF. The purpose of this report was to determine prospectively whether P-wave-triggered signal-averaged ECG (P-SAE) is useful for the prediction of the transition to CAF in patients with PAF.

METHODS AND RESULTS

One hundred twenty-two consecutive patients with PAF were prospectively followed after P-SAE, echocardiography, and 24-hour Holter monitoring at study entry. The duration (Ad) and root-mean-square voltage for the last 30 ms (LP30) of the filtered P wave were measured in P-SAE. The abnormality of P-SAE for the prediction of transition to CAF was defined as Ad > or = 145 ms and LP30 < 3.0 microV. Twenty-three (19%; group 1) of the patients had the abnormality of P-SAE, whereas the others (group 2) did not. During the follow-up period (mean, 26+/-12 months), 10 patients (43%) in group 1 acquired CAF, whereas the transition to CAF was observed in only 4 patients (4%) in group 2. Kaplan-Meier analysis revealed that the transition to CAF was significantly observed more often in group 1 than in group 2 (log-rank test, P<.0001). The Cox proportional hazards regression model identified that the variables most significantly associated with the transition to CAF were Ad (chi2=8.6, P=.003) and LP30 (chi2=5.1, P=.02), although significant differences in the left atrial dimension (40.8+/-5.3 versus 37.3+/-5.5 mm, P<.01) and the number of atrial premature contractions (3641+/-4524 versus 1489+/-2895 beats/d, P<.05) were observed between groups 1 and 2.

CONCLUSIONS

These results indicate that P-SAE could be useful to identify patients at risk for the transition from PAF to CAF.

Mental deterioration in childhood epilepsy

Mental retardation is detected in 20-30% of children with epilepsy at hospitals specializing in treatment of childhood epilepsy. However, the incidence of mental deterioration in childhood epilepsy is not high. In this study, mental deterioration was found in 52 (1.8%) of the 2,880 children with epilepsy at Okayama University Hospital. The patients showing mental deterioration mostly suffered from specific epileptic syndromes, such as West syndrome, Lennox-Gastaut syndrome, severe myoclonic epilepsy in infancy and epilepsy with continuous spike-waves during slow wave sleep. These types of epilepsy show generalized electroencephalographic (EEG) abnormalities. It is presumed that mental deterioration is caused by the total effects of prolonged diffuse EEG abnormalities and the age of the patients. Antiepileptic drugs exert a relatively minor effect on mental deterioration.

Cerebral blood flow velocity in handicapped children

Using a transcranial Doppler blood flowmeter, the blood flow velocity (BFV) ratio of the middle cerebral artery (MCA) to the basilar artery (BA) was investigated in 12 patients with severe motor and intellectual disability syndrome. The BFV of the MCA was also investigated in 58 handicapped children, classified according to the severity of their motor and intellectual disability. The ratio of the MCA to the BA was lower by 2 SD from the mean of our previously reported standard value in 8 out of the 12 cases with severe motor and intellectual disability syndrome, suggesting a more profound decrease in the level of brain activity in the MCA area than that of the BA area. The BFV of the MCA mainly decreased in cases belonging to the category of the most severe motor disability (bed-ridden). Hence, it is suggested that motor disability is the main factor related to the decrease in the BFV of the MCA.

[Development of a regimen comprehension scale]

Whether elderly patients can take prescription drugs as directed by a physician is often unclear. So elderly patients could receive adequate instruction regarding their medications, we developed a regimen comprehension scale (RCS) with simple questions regarding information on dosage and administration. This information was written on the outside of the paper bags in which the medications are usually dispensed. The subjects were 21 healthy volunteers (11 men and 10 women, averaged age 38.3 +/- 11.2 years) and 17 inpatients (9 men and 8 women, averaged age 73.4 +/- 6.8 years). Five kinds of drugs, which differed with respect to dosage and administration were used. The subjects were questioned in an interview about taking the five drugs and their regimen comprehension was assessed with the RCS (maximum score: 10 points, lowest score: 10 points. Then regimen comprehension was classified into 4 grades: normal (10), caution needed (9 or 8), training needed (7 or 6), and assistance needed (5 or less). In addition, intelligence was tested with the revised version of Hasegawa's dementia scale (HDS-R). Eight of the 21 healthy volunteers (38%) and 13 of the 17 elderly patients (76%) misunderstood some aspects of the regimens written on the paper bags. The regimen comprehension was classified as "normal", "caution needed", and "training needed" in 13, 7, and 1 of the healthy volunteers, respectively, it was classified as "normal", "caution needed", "training needed", and "assistance needed" in 4, 4, 4, and 5 elderly patients, respectively. The five elderly patients classified as "assistance needed" were suspected to have dementia because they had scores on the HDS-R of 21 or less. A significant positive correlation (r = 0.797) was noted between scores on the HDS-R and on the RCS. When treating elderly patients with chronic disease (for example, hypertension) it is important to evaluate their regimen comprehension with an index such as the RCS to determine the need for medication counseling before the start of a medication regimen.

Detection of patients with sick sinus syndrome by use of low amplitude potentials early in filtered P wave

OBJECTIVES

This study sought to determine whether patients with sick sinus syndrome could be detected by analyzing the initial portion of the signal-averaged P wave corresponding to the electrical activity of the perinodal atrial myocardial cells.

BACKGROUND

In sick sinus syndrome, pathophysiologic abnormalities have been shown not only in the sinus node, but also in the atrial muscle, especially the perinodal portion.

METHODS

The study included 41 patients with sick sinus syndrome and 140 age-matched control subjects. Eighteen of 41 patients with sick sinus syndrome had paroxysmal atrial fibrillation. Signal-averaged P wave electrocardiograms (ECGs) were recorded through a bandpass filter of 40 to 300 Hz with a P wave-triggering technique. Signals of the orthogonal bipolar leads were combined into a spatial magnitude. The root mean square voltage for the initial 30 ms (EP30) and the duration of initial low amplitude signals < 4 microV (ED4) of the filtered P wave were measured. The root mean square voltage for the last 20 ms (LP20) and the duration of the filtered P wave were also measured.

RESULTS

EP30 was significantly lower and ED4 was significantly longer in patients with sick sinus syndrome than in the control subjects (EP30 [mean +/- SD]: 2.18 +/- 0.90 vs. 3.94 +/- 1.45 microV, p < 0.0001; ED4: 31.7 +/- 14.5 vs. 14.0 +/- 7.4 ms, p < 0.0001), although there was no significant difference in LP20 between patients with sick sinus syndrome without paroxysmal atrial fibrillation and the control subjects. The duration of the filtered P wave was significantly but minimally longer in patients with sick sinus syndrome than in the control subjects (139.8 +/- 18.8 vs. 127.3 +/- 13.6 ms, p < 0.0001). The criteria of EP30 < 3.0 microV and ED4 > 22 ms as atrial early potential gave a sensitivity of 76%, a specificity of 91%, a positive predictive value of 74% and a negative predictive value of 93% for identification of patients with sick sinus syndrome.

CONCLUSIONS

These results suggest that the long, low amplitude signals early in the filtered P wave on the signal-averaged ECGs are characteristic of sick sinus syndrome. Thus, the atrial early potential could be a useful marker to identify patients with sick sinus syndrome.

Effects of high-dose antiepileptic drugs on event-related potentials in epileptic children

N200 and P300 of event-related potentials (ERPs) were recorded from 22 epileptic children receiving high-dose antiepileptic drugs. The patients were undergoing monotherapy with supratherapeutic serum level and were not mentally retarded. P300 latency was prolonged in 5 of 8 patients (62.5%) of the carbamazepine (CBZ) group and in 4 of 7 patients (57.1%) of the phenytoin (PHT) group. Only one child of the PHT group showed abnormality in brain-stem auditory evoked potentials (BAEPs). Abnormality of P300 was more frequent than that of BAEP. In patients of the PHT group who underwent examinations consecutively before and after changing the dose, P300 latency was prolonged rapidly when the PHT level exceeded 30 micrograms/ml. This suggested that the prolongation was dose dependent. In all patients of the valproic acid (VPA) group, P300 latency was normal. Only 2 patients of the PHT group had P300 prolongation simultaneously with clinical signs of intoxication. Others demonstrated changes in P300 without symptoms of side effects.

[Two cases of cavity formation in prostatic urethra after transurethral microwave thermotherapy (TUMT) with Prostatron]

The Prostatron device, developed by Dr. Devonec, provides microwave heating of the prostate and simultaneous conductive cooling of the urethra. Treatment with Prostatron (transurethral microwave thermotherapy: TUMT) of BPH can be performed in a single session, and the urethra, the rectum and the surrounding tissue are protected with the temperature monitoring system. TUMT with Prostatron may be more suitable for a small adenoma with mild symptoms than a large adenoma with severe symptoms, because objective improvement is rarely observed compared with subjective improvement. We have treated 40 cases of BPH with Prostatron (Prostasoft 2, max. energy: 50 watt, max. urethral temperature: 44.5 degrees C, max. rectal temperature: 42.5 degrees C) since March 1993. Among them, there were 2 cases of large cavity formation involving the prostatic urethra. With cavity formation, TUMT may have its place in the treatment of a large adenoma with severe urinary symptoms, but loses its advantage in the prevention of persistent urinary infection and retrograde ejaculation, especially in the treatment of a small adenoma in a younger patient with mild urinary symptoms. It is unknown why such cavity formation occurred only in 2 patients among 40 equally treated cases, but the causes of cavity formation and safety of TUMT should be evaluated again, even though no injury to the rectum and the external urethral sphincter were detected. We report these 2 cases, and causes of cavity formation and discuss the prospects of TUMT.

Tumour affinity of 203Pb-chloride: comparison with 67Ga-citrate and 201Tl-chloride

The radionuclide 203Pb decays completely by electron capture to stable 203Tl with a half-life of 52 h. The primary radiation from the decay is gamma-ray radiation 280 keV (80%). 203Pb is produced easily from the natural metal thallium by the method described below. 203Pb-chloride is a promising imaging agent for tumour scanning because of the large retention value for tumour tissue and the small value for normal organs, but the large value for the kidney and bone is a shortcoming when considering it as an imaging agent. The retention value of 203Pb in tumour tissue is larger than that of 201Tl and smaller than that of 67Ga. The tumour/inflammatory lesion retention ratio for 203Pb is very large in comparison with those for 67Ga and 201Tl. 203Pb accumulates to a large extent in viable tumour tissue, and less in necrotic tumour tissue and in inflammatory lesion. Therefore, 203Pb-chloride is far better for visualization of viable tumour tissue than 67Ga and 201Tl if the large retention values for the kidney and bone were reduced.

The effects of age on the N200 component of the auditory event-related potentials

This study was undertaken to determine the effects of development and aging on N200 of event-related potentials from childhood to adulthood. Event-related potentials were recorded from 164 normal subjects ranging in age from 4 to 77 years. A total of 127 of the 164 subjects demonstrated N200 peaks. N200 showed marked developmental changes. During childhood, the N200 latency decreased rapidly with age to the minimum (217 +/- 17.3 ms) at 16 years of age, while it was prolonged gradually with age during adulthood. The latency/age slope in the subjects from 5 to 15 years of age was -9.03 ms/year, while +0.97 ms/year in those from 16 to 77. The N200-P300 interpeak latency remained constant in all age groups and showed no age-related changes. The N200 amplitude decreased as age increased. Nineteen young cases showed N200 peaks to the frequent stimuli. Their ages ranged from 5 to 17 years. Our study suggests that N200 is valuable in evaluating the developmental and aging processes in the central nervous system. The results of this study could be used as normative data in clinical practices.

Developmental and physiologic changes in cerebral blood flow velocity

Developmental change of mean blood flow velocity (MBFV) and resistance index of the basilar artery (BA), as well as the changes in MBFV of the BA and the middle cerebral artery (MCA) during sleep and hyperventilation, were studied using transcranial Doppler sonography in healthy Japanese subjects. The MBFV of the BA increased with age from infancy through early childhood, reaching the maximum (64.4 +/- 2.6 cm/s) at the age of 5 y, and then gradually decreased. MBFV ratio of MCA to BA was almost stable between 1.57 to 1.64 in all age groups. The resistance index of the BA showed a maximum value in infants, decreased in 1- to 2-y-olds, and remained constant thereafter. The MBFV of both the MCA and BA were lower during non-rapid eye movement sleep than during wakefulness, whereas during rapid eye movement sleep they showed almost the same value as during wakefulness. They were also decreased during hyperventilation. At an expiratory CO2 level of 25 mm Hg (33.33 kPa), the average decrease in MBFV in children (n = 10) was -50.1 +/- 3.9% in the BA, and -46.2 +/- 7.4% in the MCA, significantly (p < 0.05) more marked than that in adults (n = 10) (-41.5 +/- 5.9% and -37.9 +/- 4.2%, respectively). Transcranial Doppler sonography is a noninvasive method that has a potentially wide range of applications in pediatric neurology.

Image feature analysis and computer-aided diagnosis in digital radiography: automated detection of pneumothorax in chest images

In order to aid radiologists in the diagnosis of pneumothorax from chest radiographs, an automated method for detection of subtle pneumothorax is being developed. The computerized method is based on the detection of a fine curved-line pattern, which is a unique feature of radiographic findings of pneumothorax. Initially, regions of interest (ROIs) are determined in each upper lung area, where subtle pneumothoraces commonly appear. The pneumothorax pattern is enhanced by the selection of edge gradients within a limited range of orientations. Rib edges included in this edge-enhanced image are removed, based on the locations of posterior ribs that are determined separately. A subtle curved line due to pneumothorax is then detected by means of the Hough transform. The detected pneumothorax pattern is marked on the chest image displayed on a CRT monitor. With the present computer method applied to 50 chest images (28 normals and 22 abnormals with pneumothorax), we were able to detect 77% of pneumothoraces, with 0.44 false-positives per image.

Computer-aided diagnosis: development of automated schemes for quantitative analysis of radiographic images

Preliminary results obtained with computer-aided diagnosis (CAD) from various radiographic examinations are very encouraging. However, CAD is still at an early stage of its development. It will be necessary to increase further the understanding of image features of normal and abnormal patterns, to establish databases, and to devise specific approaches for particular types of pathology. Although the existing schemes are designed to be applied to digital radiographs, similar techniques can be applied in the future to cross-sectional images such as CT, MRI, and ultrasound. We believe that CAD will become clinically practical in the near future.

Image feature analysis and computer-aided diagnosis in digital radiography: automated delineation of posterior ribs in chest images

In order to facilitate computerized quantitative analysis of digital chest radiographs, an automated method for accurate delineation of posterior ribs in frontal chest images is being developed. This method is based on an analysis of vertical profiles in the lung regions and a statistical analysis of edge gradients and their orientations in small selected regions-of-interest (ROIs). A shift-variant function is fitted to vertical profiles to obtain initial estimates of locations of rib edges. Rib edges are then determined more accurately by analyzing cumulative edge gradients and their orientations in small ROIs that are located adjacent to the initially estimated edges. The present computerized method can achieve a good agreement between the detected and the actual rib structures for posterior ribs in 74% of 50 cases examined. This suggests that automated detection of posterior ribs by a computerized method is feasible, and may be useful for computer-aided diagnostic schemes in the chest.

Comparison of imaging properties of a computed radiography system and screen-film systems

To compare the diagnostic quality of images obtained with a computed radiography (CR) system based on storage phosphor technology with that obtained with conventional screen-film systems, a dual-image recording technique was devised. With this technique, a CR imaging plate is placed behind a screen-film system in a conventional cassette. This makes it possible to obtain two images simultaneously, one from each system, in a clinical examination with the same patient positioning, the same degree of patient motion, the same geometric unsharpness, and no additional exposure. The modulation transfer functions (MTFs) of the CR system with and without the dual-image recording technique were greater at low frequencies, but lower at high frequencies, that the MTFs of the screen-film systems used. The noise Wiener spectra of the CR images at the plane of the imaging plate were greater than those of the screen-film systems, but were comparable to those of the screen-film systems at the plane of the printed film due to the reduction in image size. Clinical chest images obtained with the dual-image recording technique appeared comparable, probably because of the image size reduction and the use of mild unsharp mask processing.

Direct comparison of conventional and computed radiography with a dual-image recording technique

To compare the image quality of computed radiographic (CR) with conventional screen-film images, the authors used a dual-image recording technique. Images were simultaneously acquired with a conventional screen-film combination and a storage-phosphor imaging plate loaded into a single cassette. Wiener spectra and modulation transfer function were compared for both image types. A preliminary observer performance test was conducted with chest images obtained with the dual-image recording technique on portable and fixed equipment. Analysis of physical parameters and observer test results suggests that the conventional screen-film system can provide slightly superior image quality, although the CR system has some advantage in bedside applications.

Data compression: effect on diagnostic accuracy in digital chest radiography

High-resolution digital images make up very large data sets that are relatively slow to transmit and expensive to store. Data compression techniques are being developed to address this problem, but significant image deterioration can occur at high compression ratios. In this study, the authors evaluated a form of adaptive block cosine transform coding, a new compression technique that allows considerable compression of digital radiographs with minimal degradation of image quality. To determine the effect of data compression on diagnostic accuracy, observer tests were performed with 60 digitized chest radiographs (2,048 x 2,048 matrix, 1,024 shades of gray) containing subtle examples of pneumothorax, interstitial infiltrate, nodules, and bone lesions. Radiographs with no compression, with 25:1 compression, and with 50:1 compression ratios were presented in randomized order to 12 radiologists. The results suggest that, with this compression scheme, compression ratios as high as 25:1 may be acceptable for primary diagnosis in chest radiology.