Temporal and spatial expression of Smads and their correlation with YAP1 expression in sheep

The temporal and spatial patterns of Smad and Yes-associated protein 1 (YAP1) expression were investigated in skeletal muscle (gastrocnemius muscle and extensor digitorum longus) at different growth stages (2 days old, 2 and 6 months old) in Hu sheep. Smads were differentially expressed in sheep skeletal muscle, with high expression in the gastrocnemius muscle and lower expression in the extensor digitorum longus. Expression of Smad2, Smad3, and Smad4 at the 2-day-old stage was significantly higher than at other stages (P < 0.05). The expression of Smad7 in 2-day-old sheep was lower than in 6-month-old sheep, with the lowest levels at 2 months. Smad expression was higher in males than in females at the 2-day-old stage, and expression in 2- and 6-month-old males was lower than that in 2-day-old females. Smad3 expression was higher in the 2-day- and 2-month-old males than in the females. There was a positive correlation (P < 0.01) between YAP1 and Smad2 expression in gastrocnemius muscle at the 2-month-old stage. YAP1 and Smad4/7 expression were positively correlated (P < 0.01) in extensor digitorum longus at the 2-day-old stage. YAP1 expression was negatively correlated with Smad7 in the extensor digitorum longus at 6 months. A significant difference between Smad2 and Smad3 (P < 0.01) expression in muscle was observed, consistent with Smad3 and Smad4 expression, indicating that these inhibit transforming growth factor-β signaling in the same way. There was a positive correlation (P < 0.01) between YAP1 and MSTN expression, suggesting that YAP1 participates in muscle growth in sheep.

Analysis of the spatiotemporal expression of major genes in the TGF-β/Smad signaling pathway and correlation analysis using Hu sheep muscle tissue

The mRNA expression levels of key genes (Smads, MSTN, and MyoG) in the TGF-β/Smad signaling pathway in Hu sheep at different growth stages (2 days, 2 months, and 6 months of age) and in different skeletal muscles (longissimus dorsi muscle and soleus muscle) and different genders were detected; and correlation of the Smad family (Smad2, Smad3, Smad4, and Smad7), MSTN, MyoG expressions was analyzed in Hu sheep. The results showed that the expression of Smads was higher in the soleus muscle than in the longissimus dorsi muscle; the expressions of Smad2, Smad3, and Smad4 were significantly higher in 2-day-old sheep than in sheep belonging to the other age groups (P < 0.05); the expressions of Smad2, Smad4, and Smad7 were higher in rams than in 2-day-old ewes, but lower in rams than in 2-month-old and 6-month-old ewes; and the expression of Smad3 was higher in rams than in 2-day-old and 2-month-old ewes, but lower in rams than in 6-month-old ewes. In the 2 different muscle tissues, expression of Smad2 was significantly positively correlated (P < 0.01) with that of Smad3. The expression of Smad3 was significantly positively correlated (P < 0.01) with that of Smad4, which showed that the Smad family genes could have an inhibitory effect on the TGF-β/Smad signaling pathway.

Crosslinking Modification of UHMWPE Fibers by Ultra-violet Irradiation

By means of ultra-violet (UV) irradiation with photoinitiator and multifunctional crosslinking agent, the crosslinking modification of ultrahigh molecular weight polyethylene (UHMWPE) fibers prepared by gel spinning was performed. Thermal and mechanical properties of fiber samples were examined using differential scanning calorimeter, thermo-mechanical analysis apparatus and tensile tester, the gel content of fibers was measured by a standard device, the fiber surface was examined by scanning electron microscope. The results indicate that the optimal irradiation time is 1 to 2 hours. The modified fiber can then preserve its original mechanical properties, or may have better behavior, meanwhile, such fibers have improved heat- and creep-resistant behaviors.

The effect of gamma-irradiation on the viability of Cryptosporidium parvum

Cryptosporidium parvum is 1 of the major causative organisms in waterborne diarrheal illness. Not only does C. parvum spread ubiquitously in our environment, it is also highly resistant to harsh environmental conditions and disinfectants. Therefore, a control measure for this protozoon is urgently required. This study investigated the effect of gamma-irradiation, in the range of 1,000-50,000 Gy, on the viability of C. parvum oocysts. Oocyst viability was determined by a combined indirect immunofluorescence and nucleic acid staining and animal infectivity study. The proportion of viable oocysts estimated by nucleic acid staining ranged from 94.2 to 89.4% in the 0- to 10,000-Gy groups, whereas it was reduced significantly to 58.6 or 45.7% in the 25,000- or 50,000-Gy group, respectively, at 24 hr postirradiation. In an animal infectivity study, oocysts irradiated with less than 10,000 Gy induced infections in mice wherein there were low numbers of oocysts per gram of feces amounting to 8-10.8% of the values in control mice, whereas with 50,000 Gy-irradiated oocysts, no oocysts were produced in the mice. This study suggests that at least 50,000 Gy of gamma-irradiation is necessary for the complete elimination of oocyst infectivity in mice.

A common oocyst surface antigen of Cryptosporidium recognized by monoclonal antibodies

Two hybridoma clones, CMYL3 and CMYL30, were generated by immunizing Balb/c mice with excysted oocysts of Cryptosporidium muris. Both clones secreted monoclonal antibodies against an oocyst-wall antigen with apparent molecular mass of 250 kDa (called CM250) from C. muris and C. parvum. The epitope appeared to be periodate-sensitive, suggesting the involvement of a carbohydrate moiety. Immunofluorescence and confocal microscopy on purified oocysts and infected mouse tissues revealed staining confined to the oocyst wall of both Cryptosporidium species. Immunogold labeling further revealed the presence of the CM250 antigen in electron-dense vesicles and cytoplasm of developing macrogametocytes, and ultimately localized to the oocyst wall of mature oocysts. Both antibodies cross-reacted with C. serpentis oocysts but did not recognize the other enteropathogenic protozoans Giardia muris, Eimeria falciformis and E. nischulz. These antibodies may be valuable tools for the analysis of oocyst-wall formation in Cryptosporidium and characterization of the common antigen.

Calreticulin, a calcium-binding molecular chaperone, is required for stress response and fertility in Caenorhabditis elegans

Calreticulin (CRT), a Ca(2+)-binding protein known to have many cellular functions, including regulation of Ca(2+) homoeostasis and chaperone activity, is essential for heart and brain development during embryogenesis in mice. Here, we report the functional characterization of Caenorhabditis elegans calreticulin (crt-1). A crt-1 null mutant does not result in embryonic lethality but shows temperature-dependent reproduction defects. In C. elegans CRT-1 is expressed in the intestine, pharynx, body-wall muscles, head neurons, coelomocytes, and in sperm. crt-1 males exhibit reduced mating efficiency and defects late in sperm development in addition to defects in oocyte development and/or somatic gonad function in hermaphrodites. Furthermore, crt-1 and itr-1 (inositol triphosphate receptor) together are required for normal behavioral rhythms. crt-1 transcript level is elevated under stress conditions, suggesting that CRT-1 may be important for stress-induced chaperoning function in C. elegans.

A human case of gastric infection by Pseudoterranova decipiens larva

We report a case of gastric pseudoterranoviasis proven by gastrofiberscopy on Dec. 13, 1994. The 34-year-old male patient, residing in Chungju-shi, was admitted to Konkuk University Hospital complaining of prickling epigastric pain. The symptoms suddenly attacked him two days after eating raw marine fish at Chonan-shi. By the gastrofiberscopic examination, a long white-yellowish nematode was found from the fundus region of stomach. The worm was 34.50 x 0.84 mm in size, and was identified as a 3rd stage larva of Pseudoterranova decipiens judging from the position of the intestinal cecum. This is the 12th confirmed case of human pseudoterranoviasis in Korea.

An epidemiological survey on Cryptosporidium parvum infection of inhabitants in Chorwon-gun, Kangwon-do

The present study was undertaken to know the infection status of Cryptosporidium parvum among the residents of Chorwon-gun, Kangwon-do in 1993. Total 461 fecal samples were collected from the inhabitants residing in Chorwon-gun during the period of August 12 to September 14, 1993. Fecal smears were prepared by formalin-ether sedimentation, and examined after modified acid fast staining. Of the 461 fecal samples, 9 (1.9%) were positive for C. parvum oocysts. The positive cases were limited to thirties (4) patients, forties (3), and sixties (2), and no oocyst was detected in other age groups. The oocyst positive rate for male was 1.4% and that of female was 2.6%.

Localization of cytoskeletal proteins in Pneumocystis carinii by immuno-electron microscopy

Pneumocystis carinii causes serious pulmonary infection in immunosuppressed patients. This study was undertaken to observe the cytoskeletal proteins of P. carinii by immuno-electron microscopy. P. carinii infection was experimentally induced by immunosuppression of Sprague-Dawley rats for seven weeks, and their lungs were used for the observations of this study. The gold particles localized actin, tropomyosin, and tubulin. The actin was irregularly scattered in the cytoplasm of the trophic forms but was much more concentrated in the inner space of the cell wall of the cystic forms called the inner electron-lucent layer. No significant amount of tropomyosin was observed in either trophic forms or cystic forms. The tubulin was distributed along the peripheral cytoplasm and filopodia of both the trophic and cystic forms rather than in the inner side of the cytoplasm. Particularly, in the cystic forms, the amount of tubulin was increased and located mainly in the inner electron-lucent layer of the cell wall where the actin was concentrated as well. The results of this study showed that the cell wall of P. carinii cystic forms is a structure whose inner side is rich in actin and tubulin. The location of the actin and tubulin in P. carinii suggests that the main role of these proteins is an involvement in the protection of cystic forms from the outside environment by maintaining rigidity of the cystic forms.

The effect of microfilament inhibitor on the Cryptosporidium infection in vitro

This study was focused on the effects of microfilament inhibitor, Cytochalasin D (CD) on the invasiveness of sporozoites of Cryptosporidium spp. into the host cells. MDCK and AGS cell lines were used as host cells for C. parvum and C. muris, respectively. When MDCK cells were pretreated with CD for 1 hr before inoculation of the sporozoites, C. parvum infection was significantly inhibited when compared to the control cells. These inhibitory effects of CD on the rate of infection were dose-dependent. In addition, C. muris infection was hampered when AGS cell lines were pretreated with CD. However, the capability of invasiveness of the sporozoites into the host cells was not greatly influenced by the pretreatment of sporozoites with CD before infection. These results suggest that microfilaments of host cells, rather than parasites, play an important role for the invasion of Cryptosporidium spp.

Purification of a 68-kDa cysteine proteinase from crude extract of Pneumocystis carinii

The present study intended to verify activities of cysteine proteinase of Pneumocystis carinii from rats and to purify the enzyme. In order to exclude the contamination of host-derived enzymes, concentrates of P. carinii was primarily treated with a mixture of proteinase inhibitors before lysis of P. carinii. A 68-kDa cysteine proteinase was finally purified from the crude extract of P. carinii by 4 sequential chromatographic methods. The enzyme showed an optimal activity at pH 5.5 in 0.1 M sodium acetate, and its activity was specifically inhibited by L-trans-epoxy-succinylleucylamido (4-guanidino) butane (E-64) and iodoacetic acid, suggesting that the enzyme is a cysteine proteinase. The 68-kDa proteinase weakly digested macromolecules such as collagen, hemoglobin and fibronectin. The present study demonstrated the activity of cysteine proteinase at the 68-kDa band of P. carinii, and purified and characterized the molecule.

Genetic heterogeneity of Pneumocystis carinii from rats of several regions and strains

Pneumocystis carinii is a major opportunistic pathogen which has been found in the lungs of a wide variety of mammalian host species, and the fact suggests the possibility of intraspecific variation. Until now, P. carinii from different mammalian species are differentiated as subspecies, and the rats are known to be infected by two subspecies. The present study investigated genetic heterogeneity of P. carinii isolates from two strains of rats in Korea and China by molecular karyotyping, RFLP and sequencing analysis. Karyotypes of P. carinii were grouped into three, two from two strains of rats in Korea and one from rats in China. However RFLP of PCR product of ribosomal and MSG gene of the P. carinii isolates showed same pattern. The sequence homology rates of alpha-tubulin DNA of the P. carinii isolates were 96% in Seoul Wistar rats, 93% in Seoul Sprague-Dawley rats, and 85% in Chinese Sprague-Dawley rats. The present finding confirmed that P. carinii from rats in Korea are grouped into two karyotype strains which are different from that of P. carinii from rats in China. The Chinese isolate shows a little different sequences of alpha-tubulin DNA.

In vitro infection of Cryptosporidium parvum to four different cell lines

To determine a suitable condition for in vitro infection model of Cryptosporidium parvum, four different cell lines, AGS, MDCK, HCT-8 and Caco-2, were used as host cell lines which were cultured at various concentrations of added supplements. These supplement include fetal bovine serum (FBS), sodium choleate, ascorbic acid, folic acid, calcium pantothenate, para-aminobenzoic acid and pyruvate and their effects on the cell lines which were infected with C. parvum were evaluated. The results of this study showed that the AGS cell line was most susceptible to C. parvum whereas the Caco-2 cells appeared to be least susceptible to C. parvum. In regards to the serum condition, 10% FBS was suitable for the growth of AGS and HCT-8 cells, and 1% FBS was good for the growth of the MDCK cells when they were inoculated with C. parvum. Vitamins had a positive effect on the AGS cells, and pyruvate also showed positive effects on all of the cell lines except for Caco-2. Modified medium for each cell line was prepared by adding appropriate amounts of each supplement which resulted in the highest parasite infection number. Modified media increased the number of parasites infected on AGS cells to 2.3-fold higher when compared to the control media. In this study, we found that the AGS cell line was a suitable host model for evaluating C. parvum in vitro study and the media contents for the optimal infection conditions were suggested.

Variation of antigenicity and serological reaction to Pneumocystis carinii in Korea

The present study observed the variation of antigenicity of Pneumocystis carinii and serum IgG antibody reaction to the antigens from different localities in Korea. Antigens of rat P. carinii and sera of inhabitants were collected at Chunchon. Chungju, Kwangju, and Seoul during 1995-1996. Enzyme-linked Immunosorbent Assay and immunoblot were used for immune reaction. Absorbance of 1,294 human sera ranged between 0.01 and 0.93. Sera from Chunchon showed higher absorbances than those from other areas. Immunoblotting revealed IgG antibody reactions to 116, 100, and 45-55 kDa antigenic bands of rat P. carinii, but the frequencies of positive reaction to individual bands were variable by localities. Total 62.6% of the sera showed the reaction to 116 kDa band while 37.7% reacted to 100 kDa band and 32.0% to 45-55 kDa bands. For the reaction to 116 kDa, the reaction rate was 60.0% to 82.6% by localities. It is found that the reaction rates of the human sera to rat P. carinii antigen are variable according to the localities. Also, the high molecular antigen of 116 kDa of rat P. carinii is the most frequent antigenic band reacting to human sera.

Biomechanics of the Bankart repair: the relationship between glenohumeral translation and labral fixation site

The specific aim of this study was to quantify glenohumeral translations in cadaveric shoulders after repair of the superior and middle regions of a surgically created Bankart lesion and after repair of the superior, middle, and inferior regions of the same lesion. Anterior-posterior, superior-inferior, and medial-lateral translations in nine cadaveric specimens were tested with shoulders in 0 degree, 45 degrees, and 90 degrees of humeral abduction and varying degrees of humeral rotation. There was statistically significantly less anterior and inferior translation after three-site labral repair compared with after two-site labral repair, and this effect was greatest at 90 degrees of glenohumeral abduction. The decreased translations demonstrated with three-site repair emphasized the importance of careful repair of the labrum to the inferior glenoid rim during a Bankart reconstruction and suggested that failure to do so may be a contributing factor to recurrent instability after anterior shoulder reconstruction.

Distribution of actin and tropomyosin in Cryptosporidium muris

Actin and tropomyosin of Cryptosporidium muris were localized by immunogold labeling. Two kinds of antibodies for actin labeling were used. The polyclonal antibody to skeletal muscle (chicken back muscle) actin was labeled on the pellicle and cytoplasmic vacuoles of parasites. The feeder organelle has showed a small amount of polyclonal actin antibody labeling as well. Whereas the monoclonal antibody to smooth muscle (chicken gizzard muscle) actin was chiefly labeled on the filamentous cytoplasm of parasites. The apical portion of host gastric epithelial cell cytoplasm was also labeled by smooth muscle actin together. The polyclonal antibody to tropomyosin was much more labeled at C. muris than host cells, so it could be easily identified even with low magnification (x2,000). The tropomyosin was observed along the pellicle, cytoplasmic vacuoles, and around the nucleus also. The skeletal muscle type actin seems to play a role in various cellular functions with tropomyosin in C. muris; on the other hand, the smooth muscle type actin was located mainly on the filamentous cytoplasm and supported the parasites' firm attachment to host cells. Tropomyosin on the pellicle was thought to be able to stimulate the host as a major antigen through continuous shedding out by the escape of sporozoites or merozoites from their mother cells.

Surface ultrastructure of Metagonimus miyatai metacercariae and adults

A scanning electron microscopic study was performed to observe surface ultrastructures of excysted metacercariae and adults of Metagonimus miyatai. Metacercariae were collected from the scale of the pale chub (Zacco platypus), and adult flukes were harvested 1-4 weeks after infection to rats. In excysted metacercariae, the oral sucker was devoid of tegumental spines and had type I and type II sensory papillae. Anteriorly to the ventral sucker, spines were dense and digitated into 5-7 points, whereas near the posterior end of the body spines were sparse and digitated into 2-3 points. In one-week adults, 7 type II sensory papillae were arranged around the lip of the oral sucker, and at inner side of the lip one pair of small and two pairs of large type 1 sensory papillae were seen on each side. The distribution of tegumental spines was similar to that of metacercariae, but they were more differentiated with 9-11 pointed tips. In two- to four-week old adults, the surface ultrastructure was nearly the same as in one-week old adults, however, sperms were frequently seen entering into the Laurer's canal. Conclusively, the surface ultrastructure of M. miyatai was generally similar to that of M. yokogawai, however, differentiation of tegumental spines and distribution of sensory papillae around the oral sucker were different between the two species, which may be of taxonomic significance.

Expression patterns of proliferating cell nuclear antigen in the small intestine of mice infected with Metagonimus yokogawai and Metagonimus Miyata type

Genus Metagonimus has been a subject of taxonomic debates for several years. In morphological aspects, M. yokogawai has been thought to have three subtypes, namely Yokogawa type (M. yokogawai in strict sense), Miyata type and Koga type, But differences in the intestinal pathology induced by these subtypes have not been studied yet. In this study we compared the pathological reactions induced by M. yokogawai and Metagonimus Miyata type using proliferating cell nuclear antigen (PCNA) index. Metacercariae (Mc) of M. yokogawai were collected by artificial digestion of Plecoglossus altivelis and Mc of Metagonimus Miyata type were collected from Zacco platypus. Three hundreds Mc of each species were infected orally to ICR mice. The mice were sacrificed at 3, 6, 10, 16 and 23 days after infection and the small intestines were resected into three portions (proximal, middle, and distal). Immunohistochemical staining for PCNA was done using PC-10 (DAKO-PCNA, CA, USA). The PCNA indices in M. yokogawai infected group on the 6th and 23rd day after infection were lower than in the control and Miyata type infected groups (p < 0.05) from all of the three intestinal regions. On the other hand, the control group and Metagonimus Miyata type infected group did not make any differences in PCNA indices. The villus/crypt (V/C) ratio was also decreased significantly in M. yokogawai infected mice but not in Metagonimus Miyata type infected ones. It is suggested that M. yokogawai induce villous atrophy through a decrease in the cell proliferation at the crypt. The results of this study suggested that M. yokogawai induce more serious intestinal pathology than Metagonimus Miyata type.

PCR-RFLP pattern of three kinds of Metagonimus in Korea

We tried to compare the three kinds of Metagonimus species, M. yokogawai, Metagonimus Miyata type, and M. takahashii, which were known to be distributed in Korea with polymerase chain reaction based-restriction fragment length polymorphism (PCR-RFLP) patterns. We amplified the internal transcribed spacer 1 (ITS1) site of ribosomal RNA and mitochondrial cytochrome c oxidase I (mCOI) gene. The restriction patterns of ITS1 gene with Rsa I, Alu I and Msp I showed multiple fragmented bands of different sizes between three kinds of Metagonimus. In case of mCOI gene, Rsa I and Alu I enzymes produced differentially fragmented band patterns. According to the parsimony analysis of PCR-RFLP patterns, the estimated genetic divergence between M. yokogawai and Metagonimus Miyata type was 0.034880, between Metagonimus Miyata type and M. takahashii was 0.028098, between M. yokogawai and M. takahashii was 0.018179. It is suggested that Metagonimus Miyata type may be separate species and evolutionize at the older time than the other two species.

Different RAPD patterns between Metagonimus yokogawai and Metagonimus Miyata type

Genomic DNA from Metagonimus yokogawai and Metagonimus Miyata type was amplified by polymerase chain reaction based on the random amplification of polymorphic DNA (RAPD) technique. Eight random 10-mer oligonucleotide primers (OPA-02, 5-TGCCGAGCTG-3; OPA-09, 5-GGGTAACGCC-3; OPA-10, 5-GTGATCGCAG-3; OPA-11, 5-CAATCGCCGT-3; OPA-13, 5-CAGCACCCAC-3; OPA-17, 5-GACCGCTTGT-3; OPA-19, 5-CAAACGTCGG-3; OPA-20, 5-GTTGCGATCC-3) with a G + C content of 60-70% (Kit A, Operon Technologies Inc., California, USA) could produce distinguishable banding patterns between the two Metagonimus species. From the results of this study, it was suggested that Metagonimus Miyata type has a different DNA sequence from M. Yokogawai.

Evaluation of fracture predilection in the calcaneus after external fixator pin removal

OBJECTIVES/HYPOTHESIS

External fixators have been advocated for the treatment of intra-articular fractures of the distal tibia, so-called "pilon" or "plafond" fractures. Current recommendations include placement of external fixator pins, which vary in diameters up to six millimeters, in the talus and calcaneus. Removal of a relatively large pin may create a large defect in the bone, theoretically increasing fracture predilection with weight bearing. The objective was to compare the compressive load at failure of intact and formerly instrumented calcanei. It was hypothesized that the pin hole defect would not lead to a clinically significant difference in compressive load at failure.

STUDY DESIGN

A biomechanical evaluation of randomized matched pairs of cadaveric calcanei.

METHODS

Fresh human calcanei were harvested, embedded in casting compound, and tested pairwise. Among pairs of calcanei, one served as the control, and the other was drilled with a 6.0-mm pin in the posterior portion. The pin was removed before biomechanical evaluation. Testing was performed in compression under displacement control on a hydraulic materials testing system.

RESULTS

There was a 22% reduction in compressive load at failure (p = 0.021) of the drilled versus intact specimens. Compared with intact calcanei, defect calcanei had a compressive failure load much closer to forces that might be encountered with walking and running.

CONCLUSIONS

The six-millimeter-pin defect is a significant stress riser, and protected, progressive weight bearing after pin removal should be recommended.

Strength and stability of posterior lumbar interbody fusion. Comparison of titanium fiber mesh implant and tricortical bone graft

STUDY DESIGN

A paired comparison was done of the bending flexibility and compression strength of tricortical bone graft and titanium fiber mesh implants in a human cadaver model of posterior lumbar interbody fusion.

OBJECTIVES

To test the hypothesis that a titanium fiber mesh implant and a tricortical bone graft provide adequate and equal mechanical strength and stability in posterior lumbar interbody fusion constructs.

SUMMARY OF BACKGROUND DATA

Although studies of posterior lumbar interbody fusion constructs have been performed, the authors are unaware of any study in which the strength and stability of a titanium fiber mesh implant are compared with those of tricortical bone graft for posterior lumbar interbody fusion in the human cadaver lumbar spine.

METHODS

Changes in neutral zone and range of motion were measured in a bending flexibility test before and after placement of posterior lumbar interbody fusion constructs. Tricortical bone graft and titanium fiber mesh implant construct stability than were compared in a paired analysis. The constructs than were loaded to failure to evaluate construct strength as a function of graft material and bone mineral density.

RESULTS

The posterior lumbar interbody fusion procedure produced statistically significant decreases in neutral zone when compared with the intact spine. No statistically significant differences in neutral zone, range of motion, or strength were detected between the two implants. Construct strength correlated strongly with bone mineral density.

CONCLUSIONS

Posterior lumbar interbody fusion procedures result in equal or improved acute stability for titanium fiber mesh implants and tricortical bone graft implants when used without additional posterior stabilization.

[Protective effect of interleukin-1 beta on acetaminophen induced liver damage in mice]

In the model of liver damage induced by acetaminophen of mice, injection of interleukin-1 beta (IL-1 beta, i.p. 50,000 U/kg) 1, 6 or 12 h before the administration of acetaminophen could reduce the leakages of GPT and GOT induced by acetaminophen, with the 12 h pretreatment being the most effective. Treatment with IL-1 beta 1 h after administration of acetaminophen had no effect. Treatment with IL-1 beta of different doses (10,000, 30,000 or 50,000 U/kg) 12 h before the administration of acetaminophen could reduce the leakages of transaminases in a dose dependent manner and decrease the mortality of mice. The protective effect of IL-1 beta on the liver could be abolished by IL-1 beta receptor antagonist. Further experiments showed that IL-1 beta could increase the content of reduced glutathione (GSH) in normal liver and reverse the decline of GSH and the increase of GSSG induced by acetaminophen. IL-1 beta could also reduce malondiadehyde (MDA) content enhanced by acetaminophen. The above results indicate that the preventive effect of IL-1 beta against liver damage due to acetaminophen may be mediated through IL-1 beta receptor by increasing glutathione synthesis and decreasing lipid peroxidation of the liver.

Localization of cytoskeletal proteins in Cryptosporidium parvum using double immunogold labeling

Actin and some actin binding proteins such as tropomyosin, alpha-actinin and troponin T were localized by simultaneous double immunogold labeling in several developmental stages of Cryptosporidium parvum. All of the observed developmental stages have many particles of tropomyosin and actin around pellicle and cytoplasm. Tropomyosin was labeled much more than the actin when these two proteins were labeled simultaneously. And alpha actinin was labeled mostly in the pellicle, but troponin T labeling was very rarely observed. From this study, it was suggested that tropomyosin seemed to be one of the major proteins of C. parvum, so it must be playing important roles in C. parvum.

Detection of Pneumocystis carinii by in situ hybridization in the lungs of immunosuppressed rats

In situ hybridization was performed to detect rat Pneumocystis carinii in the lung sections. Rats were immunosuppressed by weekly subcutaneous injection of 10 mg/kg methylprednisolone. On the 6th, 8th and 9th week of immunosuppression, the lungs were removed and fixed in 10% neutral formalin. A 22 base oligonucleotide probe complementary to P. carinii 5S ribosomal RNA was commercially synthesized and its 3' terminal was labeled with biotin. In situ hybridization was performed utilizing manual capillary action technology on the Microprobe system. P. carinii were detected along the luminal surface of alveolar pneumocytes, in exudate of alveolar cavities, and also in secretory material of bronchioles. In the 6th week group, positive reaction was observed focally in the peripheral region of the lung sections, but the reaction was observed diffusely in the 8th or 9th week groups. In comparison with Grocott's methenamine silver stain, in situ hybridization technique can detect the organism rapidly, and can detect trophic forms very well. Furthermore, no nonspecific reaction with other pathogenic fungi and protozoa was recognized. Therefore, in situ hybridization can be a good technique to detect P. carinii in the lungs of infected rats.

The role of imaging and in situ biomechanical testing in assessing pedicle screw pull-out strength

STUDY DESIGN

This study determined the predictive ability of quantitative computed tomography, dual energy x-ray absorptiometry, pedicular geometry, and mechanical testing in assessing the strength of pedicle screw fixation in an in vitro mechanical test of intra-pedicular screw fixation in the human cadaveric lumbar spine.

OBJECTIVE

To test several hypotheses regarding the relative predictive value of densitometry, pedicular geometry, and mechanical testing in describing pedicle screw pull-out.

SUMMARY OF BACKGROUND DATA

Previous investigations have suggested that mechanical testing, geometry, and densitometry, determined by quantitative computed tomography or dual energy x-ray absorptiometry, predict the strength of the screw-bone system. However, no study has compared the relative predictive value of these techniques.

METHODS

Forty-nine pedicle screw cyclic-combined flexion-extension moment-axial pull-out tests were performed on human cadaveric lumbar vertebrae. The predictive ability of quantitative computed tomography, dual energy x-ray absorptiometry, insertional torque, in situ stiffness, and pedicular geometry was assessed using multiple regression.

RESULTS

Several variables correlated to force at failure. However, multiple regression analysis showed that bone mineral density of the pedicle determined by quantitative computed tomography, insertional torque, and in situ stiffness when used in combination resulted in the strongest prediction of pull-out force. No other measures provided additional predictive ability in the presence of these measures.

CONCLUSIONS

Pedicle density determined by quantitative computed tomography when used with insertional torque and in situ stiffness provides the strongest predictive ability of screw pull-out. Geometric measures of the pedicle and density determined by dual energy x-ray absorptiometry do not provide additional predictive ability in the presence of these measures.

Localization of actin and myosin in Cryptosporidium parvum using immunogold staining

The location of actin and myosin of the several stages of Cryptosporidium parvum was observed. The tissue antigen of C. parvum was prepared through immunosuppression of ICR mice with Depomedrol. The thin sectioned specimens, which were incubated with the IgG fraction of the rabbit polyclonal antibodies raised against chicken back muscle actin and bovine uterus myosin, were treated with 10 nm gold-conjugated goat anti-rabbit IgG. Electrodense particles were located mainly on the pellicles of all observed developmental stages of the parasites. The number of actin gold particles in the cytoplasm increased when the parasite was dividing actively as in case of meronts. Especially in macrogametocytes, a lot of actin and myosin particles were synthesized and storaged as amilopectin-like bodies. There were many actin gold particles along the microspikes of cytoplasmic membranes in various developmental stages. The actin and myosin observed in this study may play important roles to control the shape of the parasites and movements of cytoplasmic membranes as cytoskeletal proteins.

[The protective effect of IL-1 beta on stress-induced gastric mucosal damage in rat]

The effect of recombinant IL-1 beta on stress-induced gastric mucosal lessions was studied in rats. Pretreatment with IL-1 beta prevented formation of gastric mucosal damage in a dose-dependent manner. IL-1 receptor antagonist peptide (IRAP) could totally reverse the protective effect of IL-1 beta. IL-1 fragment peptide (163-171) had no effect on gastric ulcer formation in the experimental model, whereas sulfhydryl blocker N-ehtylmaleimide partially blocked the protective effect of IL-1 beta. The concentration of protein and noneprotein sulfhydryls in the gastric mucosa was significantly decreased 3 h after stress, and this decrease was partially prevented by IL-1 beta. IL-1 beta also decreased the concentration of molondialdehyde (MDA) in the gastric mucosa after 3 h stress. The results suggest that IL-1 beta could effectively lessen the degree of stress-induced gastric mucosal damage, due possibly to the production of endogenous sulfhydryl compounds in the gastric mucosa.

The effect of reinfection with Neodiplostomum seoulensis on the histopathology and activities of brush border membrane bound enzymes in the rat small intestine

Neodiplostomum seoulensis, one of the human intestinal trematodes, was reinfected to albino rats, and worm recovery rates, histopathology and activity changes of the intestinal brush border membrane bound enzymes were observed. The experimental groups were three; uninfected, primary infection and reinfection. The worm recovery rate in the reinfection group was much lower than in the primary infection group 14 days after infection. The duodenal histopathology showed villous atrophy during the first and second week in the primary infection group. In the reinfection group, however, villous changes occurred as early as 3 days after the infection, and the lesion was found healed 7 days after infection. The activities of alkaline phosphatase and sucrase in the duodenum of primary infection rats decreased nearly half of the controls 2 weeks after infection, whereas the activities were unchanged in the reinfection group. However, no changes in the activities were observed in the proximal jejunum between the experimental groups. These findings suggested that a secondary infection of N. seoulensis in rats should make less damage on the intestinal mucosa than a primary infection.

Doppler-free saturation fluorescence spectroscopy of Na atoms for atmospheric application

The well-known theory of absorption and fluorescence is briefly reviewed in a systematic manner for the Na D transitions. The resulting formalism is applied to simulation of Doppler-free saturation fluorescence spectra. With only one adjusting parameter, the nonradiative rate chosen to represent the time a thermal atom takes to move across the laser beams, the simulated Doppler-free spectra match the measured ones well for both D(1) and D(2) transitions over one decade of excitation intensities. Relative to the weighted center of the six D(2) hyperfine transition lines, the frequencies of the dominant Doppler-free features have been determined from a simulated spectrum to within ±0.1 MHz to be -651.4, 187.8, and 1068.0 MHz, respectively, for D(2a), crossover, and D(2b) resonances. These features may be used as accurate frequency references for atmospheric spectroscopy. They are essential for the operation of the newly developed narrow-band Na fluorescence lidar for wind and temperature measurements in the mesopause region.

Clonorchiasis and metagonimiasis in the inhabitants along Talchongang (River), Chungwon-gun

To evaluate the status of clonorchiasis and metagonimiasis of the inhabitants near Talchongang (River) in Chungwon-gun, Chungchongbuk-do, the stools of 67 inhabitants were examined by formalin-ether sedimentation method from August to September, 1993. Also freshwater fish caught in Talchongang were examined by slide compression method. The egg positive cases of Clonorchis sinensis and Metagonimus sp. were 22 (32.8%), and 14 (20.9%), respectively. Of 17 species of examined fish. 14 species were infected with C. sinensis and 13 species with Metagonimus sp. The adult worm collected from 2 patients after treatment with praziquantel was Metagonimus Miyata type. Also the adult worm obtained from the experimental mice infected with metacercariae from Zacco platypus was Metagonimus Miyata type. We found the highly endemic area of clonorchiasis and metagonimiasis along Talchongang.

[Adenomatoid tumors in the uterus: an immunohistochemical and ultrastructural study]

In 2 cases of adenomatoid tumors of the uterus FVIII, keratin, vimentin and carcinoembryonic antigen (CEA) were observed by immunohistochemical method. No staining for FVIII and CEA were seen in the tumor cells but staining for keratin and vimentin were seen coexistent in the tumor cells. Electron microscopic finding showed tumor cells attached to one another by numerous long slender microvill. Adenomatoid tumors had typical mesothelial features. It suggests that adenomatoid tumor may be a mesothelioma.

High prevalence of Gymnophalloides seoi infection in a village on a southwestern island of the Republic of Korea

Gymnophalloides seoi (Digenea: Gymnophallidae), a new human intestinal trematode reported from a Korean woman who complained of epigastric discomfort, has been shown to be highly prevalent among the villagers of a southwestern island of the Republic of Korea. For the detection of human infections, fecal examinations were conducted on the inhabitants of a seashore village, where the first patient with a G. seoi infection had resided. Of 98 inhabitants examined, 70 (71.4%) were infected with various intestinal parasites; among them, G. seoi showed the highest rate of egg positivity 48 of 98 (49.0%). Individual worm burdens of G. seoi, as measured by collection of adult flukes after anthelmintic treatment and purgation, ranged from 106 to 26,373 specimens (average per infected case = 3,326). There was no sex-related difference in the prevalence of G. seoi, and the age distribution of the infected cases showed a relatively even pattern. This study confirms that human infection by G. seoi is not an incidental one and provides the first evidence of its high prevalence on this Korean island.

[CD5+B cells and autoimmune diseases]

By using two colour flow cytometric analysis, we examined the proportion of B lymphocytes bearing CD5 surface antigen (CD5+B cell). The level of CD5+B cells was markedly increased in active chronic ITP and active hyperthyroid patients with Graves' disease. There was an inverse correlation between the percentage of circulating CD5+B cells and platelet counts, and a positive correlation between the level of CD5+B cells in peripheral blood and serum T3 level. These results suggested that the level of CD5+B cells might play a role in producing autoantibodies in some autoimmune diseases.

[Surface ultrastructure of Parvatrema timondavidi (Digenea: Gymnophallidae) according to its developmental stages]

Surface ultrastructure of Parvatrema timondavidi developmental stages was studied using a scanning electron microscope. The metacercariae were collected from the marine clam. Tapes philippinarum, and juvenile and adult worms were recovered at 1, 2, 3 and 7 days after experimental infection of mice. The metacercariae had a large oral sucker and characteristic lateral projections. Around the lip of the oral sucker many type I and type II sensory papillae were observed, and type III papillae were located symmetrically on the medial side of the lateral projection. Numerous type I papillae were grouped around the genital pore. The tegumental spines were distributed over the worm surface except the lip of the suckers and genital pore. The 1-day old worm had a well-developed ventral sucker, with 6 type II sensory papillae on its outer surface and another 6 type I papillae on the inner side. Two small type I papillae were seen on the anterior side of the ventral sucker. The genital pore was small and opened separately from the ventral sucker and 15 type I papillae were grouped around it. The 2-, 3-, and 7-day worms revealed that as they grew to be adults, the spine tips became multipointed, the genital pore formed a genital atrium, and the cytoplasmic process became well differentiated. In 2- and 3-day worms 10 type II papillae encircling the lip of the oral sucker, and additional 4 papillae at the dorsal side of 4 dorsal type II papillae were a characteristic feature. The distribution pattern of sensory papillae around the oral sucker and genital pore, and 2 type I papillae on the anterior side of the ventral sucker, was so peculiar in P. timondavidi, that they seem to be useful keys for taxonomic differentiation from other gymnophallids.

[Submaxillary gland epidermal growth factor accelerated healing of chronic gastric mucosal lesions in rats]

Large amount of EGF-like immunoreactivity was observed in the submandibular gland of rats with immunohistochemical method. The staining is mainly localized in the ductal cells. The level of EGF in gastric juice and serum was measured with a specific and sensitive RIA method. It was observed that EGF level was decreased both in gastric juice and in serum after sialoadenectomy and subsequent healing of chronic gastric ulcer induced by serosal acetic acid was delayed. Oral administration of EGF to sialoadenectomized rats could reverse the lowered rate of ulcer healing to almost normal level. The above results suggested that secretion of EGF may have an important effect on the healing of chronic gastric lesions in rats.

[Comparative susceptibility of different cell lines for culture of Toxoplasma gondii in vitro]

In order to establish a useful cell culture system for T. gondii, we compared the degree of proliferation of T. gondii tachyzoites among 8 different cell lines; 2 kinds of normal animal cells (MDCK-canine kidney cells; Vero-monkey kidney cells) and 6 kinds of human tumor cells (A 549, PC 14-lung cancer cells; SNU 1, SNU 16, MKN 45-stomach cancer cells; HL-60-promyelocytic leukemia cells), through morphological observation and 3H-uracil uptake assay. The degree of susceptibility to infection with T. gondii tachyzoites was highest in A 549 and PC 14 cells, medium in Vero, HL-60, MDCK and SNU 1, and lowest in SNU 16 and MKN 45 cells. The kinetics of T. gondii multiplication during the post-infection 60 hours were highly dependent upon the dose of tachyzoites administered and the duration of cultivation. These results show that A 549 and PC 14 are the most suitable cell lines among the 8 tested for the growth and multiplication of T. gondii in vitro.

An epidemiological study of metagonimiasis along the upper reaches of the Namhan River

An epidemiological study of Metagonimus infection was undertaken along the upper reaches of the Namhan River, with special consideration on the species (type) of the worms collected from humans. Eggs of Metagonimus spp. were detected from 15 (9.7%) of 154 people examined in Umsong-gun, and from each infected person (5 cases) 6,015-24,060 worms (mean 13,233) were recovered after treatment with praziquantel (10 mg/kg). Eggs were also detected from 37 (48.1%) of 77 people in Yongwol-gun, from whom (27 cases) 1-4,965 worms (means 1,215) were collected. The worm from Umsong-gun consisted of both Metagonimus Miyata type and Metagonimus takahashii, whereas those from Yongwol-gun consisted of only Metagonimus Miyata type. When the uterine eggs of the two kinds and M. yokogawai (obtained from people in Tamjin River basin) were morphologically compared, it was suggested that the egg size should be a good indicator for discrimination of the species or type. The source of human infection was proved to be fresh water fishes; 49 of 52 Zacco platypus examined, 6 of 8 Hemibarbus longirostris, 13 of 15 Pseudogobio esocinus, 4 of 6 Odontobutis obscura interrupta, and 17 of 18 Carassius carassius were found infected with Metagonimus metacercariae. From the results, it is concluded that the upper reaches of the Namhan River are endemic foci of Metagonimus Miyata type and M. takahashii.

Parvatrema timondavidi (Digenea; Gymnophallidae) transmitted by a clam, Tapes philippinarum, in Korea

Metacercariae of Parvatrema timondavidi (Digenea; Gymnophallidae) were found from Tapes philippinarum, one of the most common marine clams in Korea. T. philippinarum was collected from a fishery market in Seoul, and all of the clams examined were found to contain many gymnophallid metacercariae. To get adult worms, 10 ICR mice were fed with 100 metacercariae each and sacrificed by cervical dislocation at 7, 10 and 14 days after the infection. The adult worms harvested from the intestinal contents of the mice were morphologically characterized by oval body shape, large oral sucker with lateral projections on the lip, absence of the ventral pit, single cluster of vitellaria, and separately located genital pore from the ventral sucker. Based on these characters they identified as P. timondavidi Bartoli, 1964. This study first confirms the presence of P. timondavidi metacercariae in T. philippinarum in Korea.

Secretions of the biliary mucosa in experimental clonorchiasis

The histological change of the biliary mucosa in clonorchiasis is characterized as adenomatous hyperplasia, and cross-sectioned mucosa looks like intestinal mucosa. In addition to the glandular hyperplasia, the metaplasia of mucin secreting cells is also known. The present study investigated the presence of intestinal secretion from the biliary mucosal cells of rabbits and rats with Clonorchis sinensis infection. The rabbit was infected with 300 and the rat was infected with 100 metacercariae of C. sinensis. A part of the animals were followed up after praziquantel treatment. The rabbit livers were prepared for histochemistry to observe any endocrine secretion and the bile duct mucosa of the mice was processed for the activity of brush border membrane (BBM)-bound enzymes of the small intestine. Immunohistochemistry with the polyclonal antibodies and biotin-streptavidin-peroxidase staining kit showed no positive cells for gastrin and secretin, but a few cells were positive for serotonin. The proliferated biliary mucosa of the mice revealed no activity of disaccharidases and aminopeptidase. Only alkaline phosphatase activity was found both in the control and the infected. The hyperplastic biliary mucosal cells showed no gastrointestinal secretory functions. The serotonin secreting cells may be one of the inflammatory cells.

[Study of the autologous mixed lymphocyte reaction in patients with chronic ITP]

Autologous mixed lymphocyte reaction (AMLR) was studied in 37 patients with chronic ITP (including 27 active cases and 10 inactive cases) and 37 sex and age group matched healthy controls. AMLR was markedly decreased in all the patients of both active and inactive groups (P < 0.05). T cells and non-T cells from the peripheral blood of 10 patients with ITP and 10 Sex and age group matched healthy controls were investigated for HLA-DR expression by direct immunofluorescence. The percentage of DR+ non-T cells was significantly decreased in Patients with ITP as compared with the controls (P < 0.01) and there was a positive between AMLR and platelet counts (r = 0.92, P < 0.01; r = 0.75, P < 0.05 respectively). In addition, the percentage of DR+T cells was significantly increased in patients with ITP in comparison with the controls (P < 0.01). There was an inverse correlation between the percentage of DR+T cells and platelet counts (r = -0.82, P < 0.01) as well as AMLR (r = -0.81, P < 0.01). This study suggested that these were defects of the immunoregulatory function in patients with ITP as manifested by decreased AMLR, which might be related to the abnormal expression of surface DR+ antigen on non-T cells.

Karyotypes of Pneumocystis carinii from Korean rats

Molecular karyotyping was applied to Pneumocystis carinii(Pc) from two strains of experimental rats, Sprague Dawley(SD) and Fisher(F), in Korea. Field inversion gel electrophoresis and contour clamped homogeneous electric field electrophoresis resolved 15 chromosomal bands from the Pc. The size of the bands was estimated 270kb to 684kb from SD rats, and 273kb to 713 kb from F rats. The bands of 283 kb from SD rats and of 273 kb from F rats stained more brightly suggesting duplicated bands. Total number of chromosomes was at least 16, and total genomic size was estimated 7 x 10(6) bp. All of the bands from F rats hybridized to the probe of repeated DNA sequences of Pc and the band of 448 kb size was proved to contain rDNA sequences, but Pc. chromosome bands from SD rats showed no reactions to the probes. The 2 different karyotypes of P. carinii from 2 strains of rats were maintained consistently for 2 years.

High-spectral-resolution fluorescence light detection and ranging for mesospheric sodium temperature measurements

The principle and practice of narrow-band light detection and ranging (lidar) for temperature measurements are discussed, with emphasis on a new two-frequency technique for measuring mesospheric Na temperature and density profiles. The uniqueness of this narrow-band lidar lies in the transmitter whose line-shape function can be measured directly. The frequency of the laser output can be monitored simultaneously during data acquisition with Doppler-free fluorescence spectroscopy by using a laboratory Na cell. These measurement techniques along with the procedures for data analysis are described in detail. At present the absolute temperature accuracy at the Na layer peak is +/-3 K (+/-4 K) with a vertical resolution of 1 km and an integration period of 5 min (2.5 min). Potential applications and furtherimprovements in this lidar technique are also discussed.

[Protective effect of verapamil against alloxan-induced damage on pancreatic islet beta-cells in rats]

An experimental diabetes model was produced by intravenous injection of alloxan. Verapamil (40 mg/kg) administered intraperitoneally 30 minutes prior to alloxan was able to decrease serum glucose from 22.93 +/- 1.37 mmol/L to 8.79 +/- 0.83 mmol/L after 48 hours of injection of alloxan. Histological findings showed that the number of secretory granules in beta cells of the pancreatic islet of rats pretreated with verapamil was markedly increased as compared to rats treated with alloxan alone.

[Protective effect of indomethacin on alloxan-induced diabetes in rat]

Changes of concentration of serum glucose, insulin and glucagon induced by preadministration of indomethacin were observed in normal rats and diabetic rats induced by alloxan. The results demonstrated that the level of serum glucose in diabetic rats was lowered significantly after preadministration of indomethacin (10 mg/kg) dose-dependently. After preadministration of 5, 10, 15 mg/kg of indomethacin the level of serum glucose 48 h after injecting alloxan was decreased from the control value of 591.5 +/- 38.2 mg% to 559.1 +/- 53.2, 436 +/- 16.6 and 266.6 +/- 29.9 mg% respectively. The concentration of serum insulin was increased from the control 10.5 +/- 2.7 microU/ml to 31.9 +/- 7.0 microU/ml and glucagon from 550.0 +/- 27.0 pg/ml to 303.1 +/- 22.9 pg/ml after preadministration of 10 mg/kg indomethacin. Histologic observation showed that alloxan induced beta cell lesion in pancreatic islet could indeed be prevented by indomethacin to a significant extent.

[Preventive effect of bombesin on alloxan-induced diabetes in rat]

The effect of bombesin against injury on rat islet B cells was studied in three kinds of experiments: (1). In vivo experiment, it was found that preinjection of bombesin (50 micrograms/kg, sublingual v.) could effectively prevent an increase of plasma glucose and decrease of plasma insulin in diabetic rat induced by alloxan (200 mg/kg, s.c.) (2). In vitro experiment, isolated pancreas perfusion showed that alloxan-induced (14 mmol/L) perfusion fluid inhibition of insulin secretion could be reversed by pretreatment of bombesin (10(-3) mmol/L). (3). Investigation on isolated and incubated islets demonstrated that alloxan induced decrease of insulin and somatostatin secretion and increase of glucagon secretion could be prevented by bombesin. The above-mentioned results suggest that bombesin may play an important role in the regulation of plasma glucose in diabetic rat and have a potent preventive effect against the development of diabetes.

Activities of brush border membrane bound enzymes of the small intestine in Metagonimus yokogawai infection in mice

The present study intended to evaluate the influences of Metagonimus yokogawai on the activities of brush border membrane bound enzymes of the small intestine. Mice were infected with 500 metacercariae respectively, and the worm recovery, morphological changes and enzyme activities were observed chronologically. A part of them were followed after the treatment. Recovered worms decreased in number continuously after the infection, and they were less than 10% after 2 weeks and almost zero after 28 weeks. Villous atrophy and stromal inflammation were found at two locations of the proximal jejunum from 2 weeks to 4 weeks after the infection. The enzymes, alkaline phosphatase, leucine aminopeptidase and disaccharidases (sucrase, lactase, maltase, and trehalase), showed lowered activities in the duodenum and proximal jejunum of the infected mice but they increased in the distal jejunum for the first two weeks. From three weeks after the infection, the activities were gradually recovered. In one week treated mice, they recovered the activities at 2 weeks from the treatment, but there found no differences of the activities between the 3 week treated group and infected controls. The present data reveal that M. yokogawai infection induces degenerative changes of the host's intestinal mucosa not only morphologically but functionally during the initial phase of infection. The lowered enzyme activities in acute metagonimiasis should be associated with malabsorption and diarrhea.

[Experimental activation of cryptosporidiosis in mice by immunosuppression]

Cryptosporidium, a coccidian parasite first described by Tyzzer (1907) from a laboratory mouse, has become an important human enteric pathogen causing overwhelming diarrhea especially in immunocompromised patients such as AIDS. This parasite has been reported from over 20 countries and is recognized as a cosmopolitan species. In Korea, however, there has been no report on human as well as animal cryptosporidiosis. This study was performed so as to verify the presence of Cryptosporidium in Korea by activating the parasite from laboratory mice by immunosuppression. Total 65 conventionally-bred ICR mice including a control (5 mice) and 3 experimental groups (20 each) were used for this study. Group I was immunosuppressed with prednisolone injection (1 mg IM, every other day) for 7 weeks. Group II (prednisolone injection and tetracycline administration) and Group III (prednisolone injection and trimethoprim-sulfamethoxazole administration) were prepared to observe the effect of antibacterial agents on the activation of cryptosporidiosis. In fecal examinations of mice Cryptosporidium oocysts (4-6 microns in size) were detected from 1 week after the start of immunosuppression and the mice began to die. In H-E stained tissue sections of the lower jejunum, numerous very small (2-4 microns), dense, ovoid or spherical, slightly basophilic bodies were seen attached on the free border of mucosal epithelial cells. In scanning and transmission electron microscopic observations, these organisms were identified as various developmental stages of Cryptosporidium. The species is considered to be C. parvum.(ABSTRACT TRUNCATED AT 250 WORDS)