Vascular endothelial growth factor suppresses C-type natriuretic peptide secretion

Angiogenesis plays a pivotal role not only in wound healing and tumor progression but also in diabetic angiopathy, arteriosclerosis, and collateral formation of obstructive vascular diseases. Vascular endothelial growth factor (VEGF) is now thought to be an endothelium-specific and potent angiogenic factor. We previously demonstrated that C-type natriuretic peptide (CNP), originally isolated from porcine brain, is produced by endothelial cells and proposed that CNP can exert control over vascular tone and growth as a local vascular regulator. In the present study, we examined the effect of VEGF on CNP secretion from endothelial cells using the specific radioimmunoassay for CNP we developed. VEGF (1 to 100 ng/mL) dose-dependently suppressed CNP secretion from cultured bovine endothelial cells, and 100 ng/mL VEGF suppressed endothelial CNP secretion to 28% of control levels (31.7 +/- 5.5 versus 8.9 +/- 0.8 fmol/mL, vehicle versus VEGF). VEGF also suppressed CNP mRNA expression in endothelial cells 9 hours after administration. In contrast, basic fibroblast growth factor (20 ng/mL), an endothelium-nonspecific angiogenic factor, significantly stimulated CNP secretion by 290%. These results indicate that VEGF can regulate vascular tone and growth in the process of angiogenesis through suppression of endothelial secretion of CNP, which is an endothelium-derived vasorelaxing and growth-inhibitory peptide.

Auditory plasticity in cochlear implant patients

Dynamic range (DR) of cochlear implant electrodes and speech recognition scores (SRS) were chronologically studied in 23 post-lingually deaf subjects over a period of one year. DR significantly increased over one year (ANOVA, p = 0.03). When DR was compared among three groups of electrodes which were located in the inferior, ascending and superior segments of the cochlear basal turn, that in the superior segment showed the largest increase (p = 0.001), followed by those in the ascending and inferior segments. Vowel and consonant recognition scores with auditory cue were best 6 months after operation and were maintained at the level for one year. Although the time course of improvement differed between DR and SRS, a significant positive correlation was observed at 12 months after operation. Improvement of SRS could be a result of a DR increase in the superior segment of the cochlea, which should convey pitch information over the mid-frequency region.

Malignant and benign clustered microcalcifications: automated feature analysis and classification

PURPOSE

To develop a method for differentiating malignant from benign clustered microcalcifications in which image features are both extracted and analyzed by a computer.

MATERIALS AND METHODS

One hundred mammograms from 53 patients who had undergone biopsy for suspicious clustered microcalcifications were analyzed by a computer. Eight computer-extracted features of clustered microcalcifications were merged by an artificial neural network. Human input was limited to initial identification of the microcalcifications.

RESULTS

Computer analysis allowed identification of 100% of the patients with breast cancer and 82% of the patients with benign conditions. The accuracy of computer analysis was statistically significantly better than that of five radiologists (P = .03).

CONCLUSION

Quantitative features can be extracted and analyzed by a computer to distinguish malignant from benign clustered microcalcifications. This technique may help radiologists reduce the number of false-positive biopsy findings.

[Experience with 2 cases of traumatic diaphragmatic hernia occurred at the same time]

Two cases of traumatic diaphragmatic hernia (TDH) which occurred at the same traffic accident, are reported. The first case, a plain chest X-P was diagnostic of TDH. With thoracotomy and additional laparotomy, lacerated diaphragm was repaired. The second case, continual observation on plain chest X-P was useful to suspect TDH, and thoracoscopy was diagnostic. With thoracotomy diaphragm was repaired. Two patients recovered well. It has not been reported that two cases of TDH occurred at same trauma. For diagnosis of TDH, chest X-P is useful for suspicion, and thoracoscopy is useful for correct diagnosis. Surgical approach should be decided in consideration of phase, location, and complicated injuries.

Antitumor activity of vincristine encapsulated in glucuronide-modified long-circulating liposomes in mice bearing Meth A sarcoma

Liposomes modified with the uronic acid derivative palmityl-D-glucuronide (PGlcUA) have a long circulation time and tend to accumulate in the tumors of tumor-bearing mice. Taking advantage of this character, we investigated the therapeutic effect of vincristine (VCR) encapsulated in liposomes containing PGlcUA (dipalmitoylphosphatidylcholine/cholesterol/PGlcUA = 4:4:1 as a molar ratio) on tumor-bearing mice. VCR was loaded into liposomes by a remote loading method, and then free or liposomal VCR was injected intravenously into BALB/c mice bearing Meth A sarcoma implanted subcutaneously 5 days before hand. Single-dose administration of VCR (3.0 mg/kg) in PGlcUA-liposomes significantly suppressed tumor growth, and prolonged the survival time (T/C = 1.37). Furthermore, two-dose administration of the liposomes cured one third of the animals. The therapeutic effect of PGlcUA-liposomes was greater than that of control liposomes containing dipalmitoylphosphatidylglycerol instead of PGlcUA. PGlcUA-liposomes might thus be a useful tool for delivering antitumor agents to tumor tissues.

[Three cases of Lermoyez's syndrome and its pathophysiology]

Two cases of bilateral Lermoyez's syndrome and one case of unilateral Lermoyez's syndrome are reported. The patients had recurrent episodes of vertigo with improvement of hearing or tinnitus, which is characteristic is Lermoyez's syndrome. In case 1, a 48-year-old female, dehydration with glycerol or furosemide induced nystagmus and improved bilateral hearing and the gain of the vestibulo-ocular reflex, while overhydration with drinking water impaired bilateral hearing with disappearance of nystagmus. These findings indicate that she had endolymphatic hydrops in both ears, suggesting that simultaneous changes in bilateral cochlear and vestibular function induce Lermoyez's syndrome. In case 3, a 52-year-old female, which we already reported, endolymphatic collapse in both ears may have changed bilateral inner ear function, resulting in Lermoyez's syndrome. On the other hand, patients 2, a 47-year-old male, experienced a vertigo attack with improvement of unilateral hearing after defibrinogenation therapy. In this case, slowly developing insufficiency of the inner ear blood supply may have caused the gradual hearing loss. It seemed that decreasing blood viscosity by defibrinogenation allowed blood to rush into the labyrinth, causing vertigo but at the same time improving hearing. We proposed that there are two types of Lermoyez's syndrome, bilateral (cases 1 and 3) and unilateral (case 2).

Relation between distribution of viral RNA and development of histopathological changes in encephalomyocarditis virus-induced orchitis in mice

The relation between the distribution of viral RNA and the development of histopathological changes was investigated in the early stage of encephalomyocarditis (EMC) virus-induced orchitis in mice. Signals of viral RNA were first detected by in situ hybridization in a few Sertoli cells in almost intact germinal epithelia at 2 days post-inoculation (d.p.i.). The number of Sertoli cells bearing signals of viral RNA increased at 3 d.p.i. when mild degenerative changes were exceptionally found in germinal epithelia. Signals of viral RNA came to be detected not only in Sertoli cells but also in a small number of germinal cells and spermatogonia at 4 d.p.i. when mild to moderate degenerative changes developed in germinal epithelia, resulting in desquamation of degenerated cells. At the same time, virus-like particles were observed by electron-microscopy in the degenerated and desquamated germinal cells. At and after 5 d.p.i., luminal obstruction with cellular debris and inflammatory cells was generally found. These results suggest that EMC virus carried to seminiferous tubules via the blood first attacks Sertoli cells and then damages germinal cells and spermatogonia.

In vivo administration of serum thymic factor (FTS) prevents EMC-D virus-induced diabetes and myocarditis in BALB/cAJcl mice

The effect of serum thymic factor (FTS) on the D-variant of encephalomyocarditis (EMC-D) virus-induced diabetes and myocarditis in BALB/cAJcl mice was investigated. Mice pretreated with 50 or 10 micrograms of FTS were infected with 10 or 10(3) PFU of EMC-D virus. In the mice inoculated with 10 PFU of virus, 40% developed diabetes on post-infection day (PID) 14, whereas those treated with FTS (50 micrograms/administration) on day 2 and 1 before infection did not develop diabetes. FTS (10 micrograms)-pretreated mice developed diabetes. In histological observation, FTS non-treated mice which developed diabetes showed severe necrosis and inflammation of mononuclear cells in the islets of Langerhans and myocardia on 19 PID. Mice pretreated with 50 micrograms of FTS, however, manifested mild islet degeneration without any myocardial inflammation. Furthermore, in FTS non-treated mice, immunohistological staining showed a loss of insulin granules. This loss was markedly reversed and insulin granules remained largely intact in FTS-pretreated mice. Viral titers in pancreas of FTS-pretreated mice approximated well to those of non-treated mice on PID 4, 7 and 19. In mice inoculated with higher titer of EMC-D virus (10(3) PFU), however, 50 micrograms of FTS pretreatment did not change the course of these acute pathological developments (diabetes and myocarditis observed from PID 4).

Involvement of macrophages in the development of encephalomyocarditis (EMC) virus-induced diabetes in mice

The role of macrophages in the development of diabetes following infection with encephalomyocarditis (EMC) virus was examined in 3 strains of mice (DBA/2 and BALB/c: susceptible, C57BL/6: resistant). After infection with 100 plaque forming units (PFU)/head of EMC-D (highly diabetogenic variant), the incidence of diabetes at 3 days post infection (DPI) (DBA/2: 7/8, BALB/c: 3/8, C57BL/6: 0/8) was well correlated with the severity of macrophage infiltration with beta cell damage in the pancreatic islets (DBA/2: sever, BALB/c: moderate, C57BL/6: slight). Silica-pretreatment depleted macrophage infiltration in the pancreatic islets and decreased the incidence of diabetes at 7 DPI from 100% to 40% in DBA/2 and from 80% to 0% in BALB/c mice, respectively. These results suggest that macrophages play a critical role in the process of pancreatic beta cell damage in EMC virus infection in mice.

Distribution of viral RNA in the spinal cord of DBA/2 mice developing biphasic paralysis following infection with the D variant of encephalomyocarditis virus (EMC-D)

DBA/2 mice infected with the D variant of encephalomyocarditis virus (EMC-D) (10(1) PFU/head) developed biphasic hind limb paralysis. As a first step in clarifying its pathogenesis, we examined the distribution of viral RNA in the spinal cord using in situ hybridization. At 3 days post inoculation (DPI), in the spinal cord of mice showing slight paralysis, viral RNA was observed in capillary endothelial cells and a few adjacent glia cells in the funiculus lateralis from thoracic to lumbar enlargement. At 7 DPI, in the spinal cord of mice showing apparent paralysis, viral RNA was observed in a larger number of glia cells in the demyelinated lesion associated with infiltration of macrophages in the funiculus lateralis and in a small number of degenerated neurons in the cornu ventrale. In the funiculus lateralis, viral RNA could not be observed after 28 DPI. On the other hand, viral RNA was observed in degenerated neurons in the cornu ventrale of mice showing the second phase paralysis at 42 DPI. Many CD4+T cells infiltrated around these degenerated neurons. These results suggest that: (1) the viral entry zone was the capillary endothelial cells in the funiculus lateralis; (2) first phase paralysis was due to demyelination caused by EMC-D and associated with macrophage infiltration; (3) second phase paralysis was due to degeneration of motor neurons bearing viral RNA associated with infiltration by CD4+T cells.

Histopathology of subacute renal lesions in mice induced by streptozotocin

Streptozotocin (SZ) was inoculated intraperitoneally to male and female mice of ICR and BALB/c strains in a different way of administration (A: single injection and B consecutive 5 days-injection) and subacute renal changes were examined light and electron microscopically 8 weeks after SZ-administration. The following changes were detected: (1) reduction in the rate of male-type Bowman's capsules in male mice, (2) karyocytomegaly of proximal tubular epithelial cells, and (3) dilation of distal tubules Tubular changes were detected with high incidence in A (males and females) and B groups (males) of ICR strain.

Histopathological sequence of hepatic and renal lesions in rats after cessation of the repeated administration of CCl4

The histopathological sequence of hepatorenal lesions in rats after cessation of the repeated administration of CCl4 (0.5 ml/kg, p.o., twice a week for 12 weeks) was examined. In the liver, cirrhotic lesions reduced rapidly after cessation of the CCl4-administration and collagen bundles surrounding the pseudolobules almost disappeared 12 weeks later. In contrast, in the kidney, vacuolation of epithelial cells in the proximal tubules disappeared rapidly but glomerular lesions progressed even after cessation of the CCl4-administration, and marked glomerulosclerosis developed 12 weeks later. Electron microscopically, marked expansion of the mesangial region due to increases of mesangial cells and matrix material, irregular thickening of the capillary basement membrane with mesangial interposition, and various degenerative changes in podocytes including deposition of small-sized droplets were observed.

Effects of fructose-induced hypertriglyceridemia on hepatorenal toxicity of acetaminophen in rats

The mode of hepatorenal toxicity of acetaminophen (AAP) was compared between fructose-induced hyper-triglyceridemic and normal rats. The hypertriglyceridemic and normal rats received a single dose of AAP (0, 750 and 900 mg/kg ip) at week 5 of fructose-treatment. At 24 hrs after AAP-dosing, they were sacrificed and examined blood biochemically and histopathologically. Hepatotoxicity as indicated by an increase in plasma ALT and AST activities and centrilobular necrosis of hepatocytes was more severe in the normal rats than in the hypertriglyceridemic ones. In contrast, nephrotoxicity as indicated by an increase in plasma urea nitrogen content and necrosis of epithelial cells in the proximal straight tubules was more severe in the hypertriglyceridemic rats than in normal ones. Thus, in the fructose-induced hypertriglyceridemic rats, as compared with normal ones, hepatotoxicity of AAP became apparently less severe, whereas nephrotoxicity of AAP became significantly more severe.

Protective effects of macrophage-derived interferon against encephalomyocarditis virus-induced diabetes mellitus in mice

The involvement of macrophages in protection against diabetes mellitus in mice of BALB/c (susceptible) and C57BL (resistant) strains infected with the B (non-diabetogenic) or D (highly diabetogenic) variant of encephalomyocarditis (EMC) virus was examined. Pretreatment with the B variant of EMC virus (EMC-B), avirulent interferon (IFN) inducer, or Corynebacterium parvum inhibited diabetes in BALB/c mice infected with the D variant of EMC virus (EMC-D). Treatment of C57BL mice with carrageenan to compromise macrophage function rendered C57BL mice susceptible to EMC-D-induced diabetes. In macrophage culture for BALB/c mice, EMC-B induced IFN at an earlier stage than did EMC-D. The C57BL mouse-derived macrophages produced more IFN than did BALB/c mouse-derived macrophages after stimulation with EMC-D. Moreover, C. parvum increased IFN production in macrophage cultures from BALB/c mice, whereas carrageenan inhibited that in macrophage cultures from C57BL mice. These results suggest that IFN derived from macrophages may have an important role in protecting mice against EMC virus infection.

Insulin sensitivity, insulin secretion, and glucose effectiveness in obese subjects: a minimal model analysis

The aim of the present study was to estimate insulin sensitivity (SI), insulin secretion, and glucose effectiveness in 14 obese subjects who were further divided into two groups: one with normal glucose tolerance and the other with impaired glucose tolerance (IGT). Glucose tolerance was determined by criteria of the World Health Organization. All subjects were Japanese. They underwent a modified frequently sampled intravenous glucose tolerance test: glucose (300 mg/kg body weight) was administered, and insulin (20 mU/kg body weight given over 5 minutes) was infused from 20 to 25 minutes after administration of glucose. SI and glucose effectiveness at basal insulin (SG) were estimated by Bergman's minimal model method. Body mass index (33.0 +/- 1.8 v 30.9 +/- 1.5 kg/m2, P > .05) and fasting insulin level (127.9 +/- 30.0 v 107.4 +/- 14.4 pmol/L, P > .05) were higher in obese IGT subjects than in normal obese subjects, but were not statistically significant. With regard to fasting glucose level, obese subjects with IGT (5.9 +/- 0.3 mmol/L) had significantly higher levels than those with normal glucose tolerance (5.1 +/- 0.2 mmol/L, P < .01). There was no significant difference in SI between the two groups (0.53 +/- 0.10 v 0.56 +/- 0.13 x 10(-4).min-1.pmol/L-1, P > .05). Pancreatic insulin secretion expressed as the integrated area of plasma insulin above the basal level during the first 19 minutes was significantly lower in obese subjects with IGT (3,366 +/- 1,495 pmol/L.min) than in those with normal glucose tolerance (16,400 +/- 4,509 pmol/L.min, P < .05).(ABSTRACT TRUNCATED AT 250 WORDS)

Expression and identification of the feline herpesvirus type 1 glycoprotein B (gp143/108)

The gene for feline herpesvirus type 1 (FHV-1) glycoprotein B (gB) has been cloned into an expression vector, pRVSVneo, containing the long terminal repeat of Rous sarcoma virus and polyadenylation signal of SV40. This expression vector containing FHV-1 gB gene, pRVSVgBneo, was transfected into Crandell feline kidney (CRFK) cells which are susceptible to FHV-1 infection. By indirect immunofluorescence analysis, the expressed gB was recognized with a panel of monoclonal antibodies (MAbs) against FHV-1 gp143/108. Immunoprecipitation analysis using a MAb 34H12 showed that molecular weights of the gB were 143 and 108 kDa under non-denaturing conditions that 108, 70, 64, and 58 kDa under denaturing conditions. The molecular weights were similar to those of the gB expressed in FHV-1-infected CRFK cells. In addition, when plasmid DNAs were injected into mice to obtain gB-monospecific serum, the pooled serum from mice inoculated with pRVSVgBneo, but not with pRVSVgDneo or pRVSVneo, recognized the FHV-1 gB polypeptides.

Vascularized allogeneic joint, muscle, and peripheral nerve transplantation

Joint, muscle, and peripheral nerve allotransplantation was done with short-term cyclosporine immunosuppression. To investigate the effectiveness of this regimen, the allografts were examined after withdrawal of cyclosporine. Using inbred rats, vascularized orthotopic allotransplantation of the knee joint, rectus femoris muscle, and great saphenous nerve was done across a major histocompatibility complex barrier. Cyclosporine was administered for 4 to 6 weeks postoperatively, and the grafts were observed until Week 12. Long-term administration of cyclosporine and nonvascularized transplantation were used as controls. Although rejection of the allografts could be delayed for 2 to 3 weeks after the withdrawal of cyclosporine, all transplanted joints, muscles, and nerves eventually were rejected completely and immunotolerance could not be induced. The joint allografts at first achieved bony union, but eventually were destroyed because of pathologic fractures. In the group treated with long-term immunosuppression, the allografts showed no rejection and functional improvement was obtained. However, rats given a high dose (10 mg/kg per day) of cyclosporine died from adverse effects of the drug by Week 12. In the nonvascularized treatment group, the results were poor in every patient, and the need for graft vascularization for skeletal tissue allotransplantation was confirmed.

[Imaging science and technology in diagnostic radiology: expectations in the second century of Roentgen's discovery of X-rays]

During the first century since the discovery of X-rays by Roentgen in 1885, imaging technology has contributed significantly to the progress of diagnostic radiology, mainly by providing various methods and techniques for production of diagnostic images. In the next century, it is expected that imaging science and technology will contribute to the most important process of diagnostic decision makings by radiologists and physicians by providing quantitative analyses of medical images using high-speed computers. The computer output may be used as a "second opinion" to assist radiologists' interpretation of images. This concept has been investigated as computer-aided diagnosis (CAD) during the last ten years in chest radiography and mammography for detection of lesions and characterization of normal and abnormal patterns. The aim of CAD is to improve the accuracy and the consistency of radiologic diagnoses. In this article, recent results are presented on the detection of lung nodules and pneumothoraces as well as quantitative analyses of interstitial infiltrates and cardiomegaly in chest radiographs. In mammography, CAD schemes are being developed for detection of clustered microcalcifications and masses. Recently, the prototype mammography intelligent workstation has been implemented in the clinical section of our department and initial clinical results from screening cases appear promising.

Dorsal skin reactions to sunlight and artificial ultraviolet light in hairless descendants of Mexican hairless dogs

Dorsal skin reactions to irradiation with two different types of ultraviolet (UV) light sources (sunlight and artificial UV light) were investigated in hairless descendants of Mexican hairless dogs. The total energy dose of solar UV exposure and artificial UV irradiation was 90 kJ/m2 and 40 kJ/m2, respectively. Histological examinations were done up to 7 days after UV irradiation (7 DAI). At 1 DAI, the solar UV-exposed skin did not show marked changes, while artificial UV irradiated skin exhibited a visible erythematous reaction and prominent histological alterations such as epidermal thickening, appearance of sunburn cells and deformation elastic fibers. At 4 DAI of solar UV-exposure, the skin color became moderately dark and noticeable pigmentation developed in the epidermis. In contrast, at 4 DAI of artificial UV irradiation, there still remained moderate degeneration in the epidermis and dermis, and delayed tanning was weak. At 7 DAI of solar exposure, delayed suntan reactions became more prominent. Histologically, there were heavy pigmentation of melanin granules mainly in the stratum basale. On the other hand, artificial UV irradiated skin showed less pigmentation. Thus, solar exposure provoked remarkable pigmentation while artificial UV irradiation brought about severe sunburn reactions in the dorsal skin of hairless dogs.

[A case of simultaneous treatment with mitral valve replacement and aorto-coronary bypass grafting of hypertrophic obstructive cardiomyopathy and coronary artery disease]

A case of surgical treatment of coexistent hypertrophic obstructive cardiomyopathy (HOCM) and coronary artery disease (CAD) in a 65-year-old male patient is reported. He had been diagnosed as HOCM and treated conservatively with beta-blocker and Ca-antagonist, but his complaints of chest oppression and palpitation had increased. Echocardiography revealed a systolic anterior motion of the mitral valve and mitral regurgitation. Cardiac catheterization showed a severe mitral regurgitation and peak systolic pressure gradient of 35 mmHg between the left ventricular and systemic artery. In addition, selective coronary angiography demonstrated a 99% stenosis in segment 7. He underwent aortocoronary bypass grafting and concomitant mitral valve replacement, and marked symptomatic and hemodynamic benefit could be achieved. This case shows the coexistence of HOCM and CAD in the same patient and suggest not only HOCM but also CAD should be routinely examined in the patient with angina, particularly when operative management is contempted. This case further suggests that simultaneous treatment of both diseases is more beneficial than single treatment of CAD or HOCM.

In vivo 31P magnetic resonance spectroscopy for evaluation of testicular function in cryptorchid rats

PURPOSE

To assess in vivo metabolism of rat testicles in experimental cryptorchidism, we used 31P magnetic resonance (MR) spectroscopy and compared testicular MR spectroscopic parameters with flow cytometric DNA analysis.

MATERIALS AND METHODS

In vivo 31P MR spectroscopy and flow cytometric DNA analysis of rat testis were performed before and during 14 days of experimental cryptorchidism.

RESULTS

The testicular phosphomonoester (PM)/ATP ratio showed a transient increase when multinuclear giant cells appeared in the seminiferous tubules. However, the ratio returned to the preoperative level when these cells disappeared. The phosphodiester (PD)/ATP ratio gradually decreased and the inorganic phosphate (Pi)/ATP ratio slowly increased. DNA flow cytometry showed a decrease in the percentage of haploid cells and an increase in the percentage of diploid cells from 7 days after cryptorchidism. The percentage of tetraploid cells did not change before and during cryptorchidism.

CONCLUSION

This study indicates that in vivo 31P MR spectroscopy in combination with flow cytometric DNA analysis provides useful biochemical and histological information for evaluation of testicular function.

Dermal histology of hairless rat derived from Wistar strain

The dermal histology of 9-week-old hairless rats derived from Wistar rats was investigated and compared with that of age-matched Wistar rats. Skin samples were taken from 4 portions: the head, dorsal and ventral skin, and foot pad. The epidermis of the 3 portions other than the foot pad was thicker in hairless rats than in Wistar rats. The hair canals of hairless rats contained lamellar cornified tissues instead of hair, and some of the hair follicles deep in the dermis exhibited cyst formation. S-100-immunoreactive cells were detected in the basal layer of epidermis and their number in hairless rats was greater than that in Wistar rats. Ultrastructurally, electron-lucent cells, i.e. Langerhans cells, which contained Birbeck granules and/or cored tubules, were observed more frequently in the epidermis of hairless rats than in that of Wistar rats. Some cells in one hairless rat, which had similar characteristics to Langerhans cells without Birbeck granules, contained confronting cisternae.

Ultrastructure of the dorsal skins of hairless descendants derived from Mexican hairless dogs

Ultrastructural characteristics of the dorsal skin of hairless descendants derived from Mexican hairless dogs (3-month-, 1-year- and 5-year-old) were investigated and compared with those of age-matched beagles. Except that beagles had no melanocytes in epidermis, there was no essential difference in ultrastructural characteristics of epidermis between hairless dogs and beagles. In the Stratum basale of epidermis of hairless dogs, a small number of melanocytes and a few Langerhans cell (LC)-like cells were observed among keratinocytes. Melanocytes contained many melanosomes and a few premelanosomes. LC-like cells were characterized by electron-lucent cytoplasm and lobulated nucleus and lacked melanin granules, tonofilaments and desmosomal attachments. Unlike LC in humans and rodents, these LC-like cells did not contain Birbeck granules. Although age-related ultrastructural changes of dorsal skin were generally not clear both in hairless dogs and in beagles, cells containing melanin granules were not infrequently observed among dermal collagen bundles in 5-year-old hairless dogs.

Computer-aided diagnosis for interstitial infiltrates in chest radiographs: optical-density dependence of texture measures

We have been developing a computerized scheme for automated detection and characterization of interstitial infiltrates based on the Fourier transform of lung texture. To improve the performance of the scheme, which was developed using digitized screen-film radiographs, optical-density dependence of both the gradient of the film used and the system noise associated with the laser scanner were investigated. Two hundred chest radiographs, including 100 abnormal cases with interstitial infiltrates, were digitized using a laser scanner. The root-mean-square (RMS) variations and the first moments of the power spectra, which correspond to the magnitude and coarseness of lung texture, were determined by Fourier transform of lung textures in numerous regions of interest (ROIs). The RMS variation was dependent upon the average optical density in the ROI, though no obvious trend existed for the first moment of the power spectrum. Dependence of the RMS variations on optical density was corrected for using the gradient curve of the film. Also, system noise associated with the laser scanner was corrected. Results indicated that the specificity was improved from 81% (without correction) to 89% (with corrections), without any loss of sensitivity (90%). Thus, the correspondence between the computer output and consensus interpretation of radiologists was improved with the new scheme compared to the previous one. This improved computerized scheme may be useful to radiologists in detecting interstitial infiltrates in chest radiographs.