Efficacy of serine protease inhibitors against Cryptosporidium parvum infection in a bovine fallopian tube epithelial cell culture system

The anticryptosporidial potential of the protease inhibitors alpha-1-antitrypsin (AAT), antipain, aprotinin, leupeptin, methoxysuccinyl-ala-ala-pro-valine chloromethylketone (MAAPVCK), soybean trypsin inhibitor (SBTI), and phenylmethylsulfonyl fluoride (PMSF) was evaluated in a bovine fallopian tube epithelial (BFTE) cell culture system. Protease inhibitor concentrations of 5, 10, 50, 100, and 500 micrograms/ ml (PMSF at 1, 2, and 3 mM) in RPMI medium were mixed with Cryptosporidium parvum oocysts and used to inoculate BFTE cell monolayers. At 24 hr postinoculation (candlejar/37 C), cells were rinsed with RPMI medium, fixed in methanol, and stained with Giemsa. Parasites were enumerated in cell monolayers by brightfield microscopy. The mean number of parasites counted in each protease inhibitor treatment group was expressed as a percentage of the mean number of parasites counted in an infection control group. Leupeptin and SBTI reduced parasite numbers to 40-50% of the control mean at 500 micrograms/ml: AAT, antipain, and aprotinin reduced parasite numbers to 10-15% at the same concentration. PMSF reduced parasite numbers to 40% of the control mean at 3 mM. MAAPVCK did not significantly inhibit cryptosporidial infection. These findings suggest that a protease component of C. parvum may be essential for host cell infection.

The Bacillus thuringiensis insecticidal toxin binds biotin-containing proteins

Brush border membrane vesicles from larvae of the tobacco hornworm, Manduca sexta, contain protein bands of 85 and 120 kDa which react directly with streptavidin conjugated to alkaline phosphatase. The binding could be prevented either by including 10 microM biotin in the reaction mixture or by prior incubation of the brush border membrane vesicles with an activated 60- to 65-kDa toxin from Bacillus thuringiensis HD-73. The ability of B. thuringiensis toxins to recognize biotin-containing proteins was confirmed by their binding to pyruvate carboxylase, a biotin-containing enzyme, as well as to biotinylated ovalbumin and biotinylated bovine serum albumin but not to their nonbiotinylated counterparts. Activated HD-73 toxin also inhibited the enzymatic activity of pyruvate carboxylase. The biotin binding site is likely contained in domain III of the toxin. Two highly conserved regions within domain III are similar in sequence to the biotin binding sites of avidin, streptavidin, and a biotin-specific monoclonal antibody. In particular, block 4 of the B. thuringiensis toxin contains the YAS biotin-specific motif. On the basis of its N-terminal amino acid sequence, the 120-kDa biotin-containing protein is totally distinct from the 120-kDa aminopeptidase N reported to be a receptor for Cry1Ac toxin.

Additive neuroprotective effects of dextrorphan and cycloheximide in rats subjected to transient focal cerebral ischemia

Previous studies have implicated both excitotoxicity and apoptosis in the pathogenesis of cerebral infarction induced by focal ischemic insults. Here we tested the possibility that the NMDA antagonist, dextrorphan, and the protein synthesis inhibitor, cycloheximide, would produce additive protective effects in a rodent model of focal ischemia-reperfusion. Transient focal cerebral ischemia was induced by a 90 min period of ligation of the right middle cerebral artery and both common carotid arteries. Administration of either 30 mg/kg dextrorphan or 0.5 mg/kg cycloheximide, given i.p. 15 min before ischemia, reduced infarct volume by about 65%. When optimal concentrations of each drug were given together, infarct volume was reduced by 87% as measured 14 days later. These observations support the idea that both excitotoxicity, and apoptosis dependent on new protein synthesis, contribute to cerebral infarction after transient focal ischemia in the rat.

Dextrorphan reduces infarct volume, vascular injury, and brain edema after ischemic brain injury

Focal cerebral ischemia confined to the cerebral cortex in the right middle cerebral artery (MCA) territory was induced by temporary ligation of the MCA and both common carotid arteries (CCAs). Reperfusion was initiated by releasing all three arterial occlusions after 90 min of ischemia. Infarct volume was morphometrically measured after triphenyltetrazolium chloride staining 24 h postischemia. Blood-brain barrier breakdown was assessed 4 h postischemia by measuring vascular permeability to fluorescein isothiocyanate-conjugated dextran (FITC-D), a macromolecule tracer. Ischemic brain edema was measured based on percent water content, 24 h postischemia. Dextrorphan (DX) 20-10 mg/kg given ip 15 min before ischemia reduced infarct volume in a dose-dependent manner with an apparent U-shaped dose-response curve; best protection was observed at 30 mg/kg. Posttreatment at 30 min, but not 60 min, was still effective. DX (30 mg/kg, given 15 min before ischemia) also reduced the postischemic increase in vascular permeability and brain edema in the right MCA cortex. Results from this study support the idea that NMDA receptor activation contributes to blood-brain barrier breakdown and brain edema after ischemic insults

[The influence of HX- I on rabbit thyroid allografts]

We studied the anti-rejection effect of HX- I, a preparation of traditional Chinese herbs, on rabbit thyroid allografts. The transplantations were performed on 28 rabbits after total thyroidectomies. The grafting sites were in their pretrachial muscles. These animals were divided into four groups, namely, Group I: homografts: Group I: allografts without medication; Group II: allografts with dexamethason (0.25 mg/(kg.d) intramuscularly), and Group IV: allografts with HX-I water solution, (5g/(kg.d), peros). The medication lasted 28 days. Blood samples were drawn every week postoperatively. Serum T3 and T4 were tested by RIA. The grafts were removed for histopathological evaluation on the 28th day postoperatively. The histopathology of rejection and survival were scored and classified. On the 7th and 14th days, serum T3 and T4 levels were almost the same between groups. On the 21st and 28th days, the T3 and T4 levels were higher in Groups I and IV than those in Group II (P < 0.05). The histopathological findings were; in Group I, damaged follicles with much lymphocytes infiltration and fibrosis, and 6 cases being rejected; in Group II, two deaths and three cases with damaged thyroid tissue and much lymphocytes infiltration; in Group IV, three cases with damaged thyroid tissue and four intact grafts. Our results indicate that HX-I and dexamethason both can inhibit rejection in thyroid allografts in rabbits, but dexamethason has more side effects HX-I has many components and the machanism of its early anti-rejection effect is worthy of further study.

Very delayed infarction after mild focal cerebral ischemia: a role for apoptosis?

The temporal evolution of cerebral infarction was examined in rats subjected to transient occlusion of both common carotid arteries and the right middle cerebral artery. After severe (90-min) ischemia, substantial right-sided cortical infarction was evident within 6 h and fully developed after 1 day. After mild (30-min) ischemia, no cortical infarction was present after 1 day. However, infarction developed after 3 days; by 2 weeks, infarction volume was as large as that induced by 90-min ischemia. These data suggest that infarction after mild focal ischemia can develop in a surprisingly delayed fashion. Some evidence of neuronal apoptosis was present after severe ischemia, but only to a limited degree. However, 3 days after mild ischemia, neurons bordering the maturing infarction exhibited prominent TUNEL staining, and DNA prepared from the periinfarct area of ischemic cortex showed internucleosomal fragmentation. Furthermore, pretreatment with 1 mg/kg cycloheximide markedly reduced infarction volume 2 weeks after mild ischemia. These data raise the possibility that apoptosis, dependent on active protein synthesis, contributes to the delayed infarction observed in rats subjected to mild transient focal cerebral ischemia.

Infectivity of preserved Cryptosporidium parvum oocysts for immunosuppressed adult mice

The present study was undertaken to determine the infectivity of Cryptosporidium parvum oocysts for immunosuppressed adult C57BL/6N mice after the oocysts had been stored from 1-48 months at 4 degrees C in 2.5% potassium dichromate. All mice inoculated with oocysts 1-18 months old developed patent infections, while mice inoculated with older oocysts remained uninfected. The prepatent period was extended from 2 to 6 or 7 days as the storage time for oocysts increased. The finding that C. parvum oocysts remain infective for mice for at least 18 months offers important economic and time-saving advantages for investigators who frequently require large numbers of oocysts that must be painstakingly purified from calf manure.

Complete development of Cryptosporidium parvum in bovine fallopian tube epithelial cells

Cryptosporidium parvum is a coccidian parasite responsible for causing protracted and life-threatening diarrheal illness in immunocompromised humans, especially patients with AIDS. The lack of medications effective in treating people suffering from cryptosporidiosis has prompted the development of in vivo and in vitro models for this disease. This study is the first to demonstrate that C. parvum can complete its entire life cycle (from sporozoite to infective oocyst) in a primary culture of bovine fallopian tube epithelial (BFTE) cells. Scanning and transmission electron photomicrographs were used to detail the ultrastructure of individual parasitic stages. Successful infections were produced by inoculating cell cultures with either oocysts or purified sporozoites. Infection of BFTE cells with C. parvum close paralleled in vivo infections with regard to host cell location and chronology of parasite development. Infecting BFTE cells with sporulated oocysts provided a reproducible and quantitative cultivation system with significantly (P < or = 0.001) higher infection rates than in Madin-Darby canine kidney cells. Oocysts produced in BFTE cells were infective for immunosuppressed adult C57BL/6N mice. Cultivation of C. parvum in BFTE cells will facilitate the study of interactions between parasites and host cells as well as provide a reliable system for evaluating anticryptosporidial compound efficacy.

Evaluation of vascular compression in trigeminal neuralgia by 3D time-of-flight MRA

OBJECTIVE

Our goal was to assess the usefulness of 3D images in the preoperative evaluation of 16 patients with surgically confirmed trigeminal neuralgia.

MATERIALS AND METHODS

The axial source images from 3D TOF MRA were evaluated for a total of 32 sides by two observers in a blinded manner, focusing on the presence of the neurovascular compression and the identification of compressing vessels. All 3D images including coronal orientation and gadolinium-enhanced images were reviewed retrospectively by another two observers together with the surgical findings.

RESULTS

In the blinded study with axial 3D images, the sensitivity was 75 and 75% with a specificity of 75 and 69% for observers A and B, respectively. By reviewing the coronal images, the relationship between trigeminal nerve and vessels became clearer, especially in sandwich-type compression. With gadolinium-enhanced images, three vessels that were not shown in the nonenhanced images could be identified. On the asymptomatic side, vascular compression could not be excluded retrospectively in five cases.

CONCLUSION

Nonenhanced axial images may not display small arteries or veins that are compressing the trigeminal nerve. Gadolinium enhancement will be necessary for those patients without demonstrable compression on nonenhanced examination. Coronal images are also helpful in the evaluation of vascular compression.

Contingent negative variation and movement-related cortical potentials in parkinsonism

The contingent negative variation (CNV) and movement-related cortical potentials (MRCPs) were recorded in 10 cases of Parkinson's disease, 10 cases of vascular parkinsonism and 10 age-matched healthy controls. The amplitude of the early CNV was smaller in the Parkinson's disease group and the vascular parkinsonism group than in the healthy control group. The latencies of Bereitschaftspotential (BP) and negative slope (NS') were longer and the amplitude of BP was smaller in the Parkinson's disease group and the vascular parkinsonism group than in the healthy control group. These abnormalities in CNV and MRCPs were improved by intravenous injection of L-DOPA.

Hemifacial spasm: three-dimensional MR images in the evaluation of neurovascular compression

PURPOSE

To assess the diagnostic accuracy of three-dimensional (3D) magnetic resonance (MR) images in the preoperative evaluation of hemifacial spasm.

MATERIALS AND METHODS

In 27 patients with surgically confirmed hemifacial spasm, the axial source images from 3D time-of-flight MR angiography were evaluated for 27 symptomatic sides and 26 asymptomatic sides by three observers in a blinded manner for neurovascular compression and identification of compressive vessels.

RESULTS

Sensitivity was 95% and specificity was 77%. Vascular compression on the symptomatic sides could be identified retrospectively in all 27 patients. On the asymptomatic sides, vascular compression could be excluded retrospectively in all but one patient. In the blinded study, as the mean value of three observers, the vertebral artery and posterior inferior cerebellar artery could be identified correctly in seven and 7.7 of seven and nine patients, respectively, whereas the compressive anterior inferior cerebellar artery was identified correctly in 7.7 of 16 patients.

CONCLUSION

Three-dimensional MR images have a high diagnostic accuracy and are useful in the preoperative evaluation of hemifacial spasm.

[Determination of sterigmatocystin in cancerous tissues, blood and urine in patients with liver and stomach cancer]

Sterigmatocystin (ST) was determined with modified Southern-Western blot and indirect competitive enzyme-linked immunosorbent assay (IC-ELISA) for 28 specimens of cancerous tissues, 13 of blood and 20 of urine in 14 patients with liver and stomach cancer. Results showed DNA-ST adduct was detected in 14 specimens of cancerous tissues and/or pericancerous tissues. ST values were higher in four of 13 patients (65-113 micrograms/kg), as compared only in one of 14 healthy persons (68 micrograms/kg). And, ST values all were very low in urine, with a maximum of 13 micrograms/kg.

[The correlation between changes of static central visual fields and posterior polar lesions in high myopia]

The static central visual fields tested by an Octopus Field Analyzer and posterior polar lesions in 53 cases with high myopia were investigated. Cases with low and moderate degrees of myopia were the controls. The results demonstrate that the visual field defects are present in the high myopic eyes and they are related to the degree of high myopia, the age of the patient and the severity of the posterior polar lesion. The visual field defects present multiform and multilevel in character and they do not completely correspond to the fundus lesions. The appearance of central relative scotomata in high myopic eyes detected by a quantified automated perimeter is prior to the appearance of macular lesions seen under an ophthalmoscope. Therefore, the quantified automated central visual field examination is helpful to the early diagnosis of macular disease in high myopia.

[Determination of modulus of elasticity of human periodontal membrane]

The modulus of elasticity of periodontal membrane, as an essential parameter indicating the mechanical character of periodontal membrane, is very important in biomechanical studies (e.g. finite element stress analysis and photoelastic analysis) of dental restoration. However, determination of modulus of elasticity of human periodontal membrane has not been reported in China, and there are differences among the foreign reports. In this study, 135 periodontal samples were collected from fresh teeth and alveoli of 6 healthy adults. Drawing and compressing test were performed. The results showed that the tensile modulus of elasticity of human periodontal membrane is between 3.35 and 4.59MPa and the compress modulus of elasticity 0.5402(+/- 0.348) MPa.

Modular structural elements in the replication origin region of Tetrahymena rDNA

Computer analyses of the DNA replication origin region in the amplified rRNA genes of Tetrahymena thermophila identified a potential initiation zone in the 5'NTS [Dobbs, Shaiu and Benbow (1994), Nucleic Acids Res. 22, 2479-2489]. This region consists of a putative DNA unwinding element (DUE) aligned with predicted bent DNA segments, nuclear matrix or scaffold associated region (MAR/SAR) consensus sequences, and other common modular sequence elements previously shown to be clustered in eukaryotic chromosomal origin regions. In this study, two mung bean nuclease-hypersensitive sites in super-coiled plasmid DNA were localized within the major DUE-like element predicted by thermodynamic analyses. Three restriction fragments of the 5'NTS region predicted to contain bent DNA segments exhibited anomalous migration characteristic of bent DNA during electrophoresis on polyacrylamide gels. Restriction fragments containing the 5'NTS region bound Tetrahymena nuclear matrices in an in vitro binding assay, consistent with an association of the replication origin region with the nuclear matrix in vivo. The direct demonstration in a protozoan origin region of elements previously identified in Drosophila, chick and mammalian origin regions suggests that clusters of modular structural elements may be a conserved feature of eukaryotic chromosomal origins of replication.

Mimosine differentially inhibits DNA replication and cell cycle progression in somatic cells compared to embryonic cells of Xenopus laevis

The plant amino acid mimosine has been reported to block cell cycle progression and DNA replication in cultured mammalian cells, perhaps by blocking initiation. In this study, we show that mimosine does not block initiation or any other step in DNA replication in embryonic cells of Xenopus laevis. Mimosine does not block DNA replication in cell-free "cycling" extracts of Xenopus eggs, nor does it block M to S phase transition in cell-free egg extracts released from metaphase arrest. Microinjection of mimosine into 4-cell embryos had no visible effect on development during the first 3 days after fertilization. Prior to the midblastula transition, when the cell cycle consists of alternating S and M phases, neither chromosomal DNA replication nor replication of microinjected plasmid DNA were inhibited by mimosine microinjected into cleaving Xenopus embryos. Microinjection of mimosine after the midblastula transition, when large endogenous stockpiles of DNA replication components have begun to be depleted and Xenopus embryonic cells have acquired G1 and G2 phases, still did not inhibit cell cycle progression or DNA replication. In marked contrast, mimosine arrested the growth of proliferating cultured Xenopus kidney epithelial A6 cells near the G1/S boundary. We conclude that mimosine appears to block DNA replication and cell cycle progression in somatic cells, but has no apparent effect in rapidly dividing Xenopus embryonic cells.

[Establishment of three-dimensional finite element models by using a series of plane section images processed with an image analysis system]

The geometric similarity and mesh dividing of finite element models directly create an effect on the results of analysis when a theoretical stress analysis is performed by the use of finite element method. The model is routinely established by means of sectioning the specimen. In this paper, a series of plane section CT images of the teeth and mandible, an image analysis system and a specially designed software for modeling three-dimensional finite element were used to establish a three-dimensional finite element model. It is a new preprocessing method for finite element applications in the field of oral biomechanism. The technique is characterized by the advantages of high similarity of the model to specimens and no damage to specimens; it is simple and easy. The images and figures can be repetitively used.

Therapeutic efficacy of paromomycin in immunosuppressed adult mice infected with Cryptosporidium parvum

The intent of this study was to evaluate the therapeutic efficacy of paromomycin in immunosuppressed adult C57BL/6N mice infected with Cryptosporidium parvum. Seven groups of 10 mice/group were used. Groups 1, 2, and 7 served as normal, toxicity, and placebo controls, respectively. Groups 2-7 were immunosuppressed with dexamethasone phosphate administered ad libitum in drinking water. Groups 3-7 were infected with C. parvum on day 7 postimmunosuppression. Groups 3-6 were treated by administering paromomycin per os for 10 consecutive days, beginning on day 10 postinfection, at dosage levels of 0.25, 0.5, 1, and 2 g/kg/day, respectively. Paromomycin was judged to be nontoxic at the dosage levels used. Groups 1 and 2 remained uninfected while groups 3-7 began shedding oocysts by day 3 postinfection. Paromomycin was therapeutically effective against C. parvum at 1 and 2 g/kg/day as determined by significant reductions in fecal oocyst shedding (P < 0.01), parasite colonization (P < 0.05), and villus atrophy (P < 0.05) in the ilea and terminal ilea of infected mice. We conclude that paromomycin may be useful in the treatment and palliation of cryptosporidiosis.

Detection of point mutations in exon 2 of the G6PD gene in Chinese G6PD variants

In the past few years, a total of 6 different mutations of the G6PD gene have been reported in China. One of these, the C6 mutation (A95-->G), accounted for about 15.4% of the Chinese G6PD variants. In order to develop a strategy for rapid detection of mutation-containing exons of the G6PD gene, we applied the single-strand conformation polymorphism (SSCP) technique to the detection of mutations in exon 2 of this gene. We observed four patients with abnormal migration patterns of the exon 2 band among 20 cases of G6PD variants. Direct PCR sequencing confirmed a T to C substitution in exon 2 that has previously been reported. This procedure is therefore of particular importance for the rapid detection of mutation-containing exons in the G6PD gene.