Efficacy of autologous plasmin for idiopathic macular hole surgery

PURPOSE

To determine whether a single intravitreal injection of autologous plasmin or a combination of plasmin and intraocular gas without peeling the internal limiting membrane (ILM) will close idiopathic macular holes.

METHODS

Eight eyes of seven patients with an idiopathic macular hole were studied. The degree of posterior vitreous detachment (PVD), vitreal liquefaction, closure of the macular hole, visual acuity, and complications following intravitreal plasmin or plasmin with gas were investigated. The removed ILM was examined by electron microscopy.

RESULTS

A PVD was created in seven out of eight eyes exposed to plasmin or plasmin with gas, however, the macular hole was not closed by either. Closure occurred in two eyes using conventional vitrectomy after the plasmin with gas injection, but peeling the ILM was required in the remaining six eyes. Vitreal fibers and glial cells were not observed on the vitreal surface of the extracted ILM.

CONCLUSIONS

A PVD was created safely and reliably although closure of the macular hole did not occur with either plasmin or with plasmin and gas injection. However, vitreous surgery became easier, and it required a shorter time to close the macular hole with intravitreal plasmin.

Effect of dibutyltin(IV) on the ultrastructure of African Trypanosoma spp

Diorganotins (R2SnX2) are compounds with a wide variety of biological properties. In an attempt to follow the morphological events and to characterize the toxic effects of diorganotins on in vitro cultured African Trypanosoma spp., the ultrastructural alterations induced on the parasites by dibutyltins (Bu2SnX2) were followed. The data obtained indicate that these compounds induced irreparable damage to the in vitro cultured bloodstream forms of the parasites. Transmission and scanning electron microscopy allowed observations on the perturbation of the kinetoplast, extensive cytoplasmic swellings, disconfiguration around the flagellar pocket and membrane disintegration. Fluorescence microscopy with 4,6-diamidine-2-phenylindole stain was also used to visualize the survival or degeneration of kDNA. Understanding the collateral cellular toxic effect of these compounds on the parasites may shed light on the possible mechanism by which they kill trypanosomes. Agarose gel electrophoresis resolution of isolated kDNAs revealed no fragmentation by these compounds following in vitro incubation at 37 degrees C. However, fragmentation was observed from the gel electrophoresis of kDNA isolated from in vitro cultured Bu2SnX2-exposed parasites. Transmission electron microscopy of the kDNAs revealed the same pattern as observed with gel electrophoresis. These results provide evidence for the possible involvement of the Bu2Sn moiety in the in vivo-induced fragmentation of trypanosomal kDNA and consequent trypanolysis. This observation also underlies the relevance of organometallics in the therapy of African trypanosomiasis.

Therapeutic importance of transplantation of a vascularised free flap for an oromandibular injury with infection and severe scar contracture

We report three patients who had transplantation of vascularised free flaps, peroneal osteocutaneous flap in two patients and radial forearm flap in one patient, for the treatment of oromandibular injuries that had not healed as a result of infection after initial treatment.

In vitro trypanocidal activity of dibutyltin dichloride and its fatty acid derivatives

Searching for new compounds against pathogenic trypanosomes has been substantially accelerated by the development of in vitro screening assays. In an attempt to explore the chemotherapeutic potential of organotin compounds and to broaden the search for newer trypanocides, fatty acid derivatives of dibutyltin dichloride were synthesized and their in vitro trypanocidal profiles studied on Trypanosoma brucei brucei, Trypanosoma brucei gambiense and Trypanosoma brucei rhodesiense. A 24-h time course experiment was conducted with various concentrations of the compounds using a 24-well microtiter plate technique. The compounds tested were trypanocidal in a dose-dependent fashion: inhibiting survival and growth, resulting in irreversible morphological deformation and the eventual death of the parasites. The minimum inhibitory concentrations of the tested diorganotins are at low micromolar ranges: from 0.15-0.75 microM for T. b. brucei, T. b. gambiense and T. b. rhodesiense. These observations suggest that organotin has chemotherapeutic potential.

Impaired protein folding, dimer formation, and heterotetramer assembly cause intra- and extracellular instability of a Y283C mutant of the A subunit for coagulation factor XIII

Factor XIII (XIII) is a heterotetramer consisting of two catalytic A subunits (XIIIA) and two noncatalytic B subunits (XIIIB). We examined the molecular mechanisms of a Y283C mutation which had previously been identified in a patient with XIIIA deficiency. The recombinant Y283C protein was labile when expressed in MEG-01 cells, which can endogenously synthesize XIIIA. We also included two other mutants, G562R and I464stop, previously characterized in a non-XIIIA-producing cell line. All these mutants exhibited decreased thermostability and resistance against proteolytic digestion when compared with the wild-type. Gel-filtration analysis revealed that the mutants were in monomer form, while the wild-type formed a dimer. These results were consistent with the prediction by molecular modeling that the mutant molecules would be misfolded. Although assembly of a heterotetramer with XIIIB was demonstrated for Y283C, its binding ability was 10% that of the wild-type. No complex formation was observed for the G562R or I464stop mutants. The wild-type was stabilized in plasma by complex formation with XIIIB, resulting in an increased resistance against proteolytic digestion. In contrast, the mutants were unstable in plasma even in the presence of XIIIB. Thus, impaired folding, dimer formation, and heterotetramer assembly of the mutant XIIIAs lead to both intra- and extracellular instability, which must be responsible for XIIIA deficiency in the patient.

Physiopathology and regulation of factor XIII

Factor XIII is a plasma transglutaminase. Transglutaminases are at least 8 enzymes which cross-link a number of proteins. This type of reaction not only enhances the original functions of substrate proteins, but also adds new functions to them. Factor XIII in plasma is a tetramer (A2B2), and the A subunit contains the active site. Although transglutaminases are homologous, the nucleotide sequences in their 5'-flanking region differ significantly. Accordingly, transcription factors play a major role in the cell type-specific expression of each transglutaminase. A variety of missense and nonsense mutations, and deletions/insertions with or without out-of-frame shift/premature termination and splicing abnormalities have been identified in the genes for A and B subunits in factor XIII deficiency. In some cases, the mRNA level of the A or B subunit was severely reduced. Molecular and cellular bases have also been explored by expression experiments and by molecular modeling. In most cases, impaired folding and/or conformational change of the mutant A or B subunit leads to both intra- and extra-cellular instability, which is responsible for factor XIII deficiency.

Novel Y283C mutation of the A subunit for coagulation factor XIII: molecular modelling predicts its impaired protein folding and dimer formation

In an Italian patient with severe factor XIII deficiency, a novel mutation, Y283C (TAT to TGT), was identified heterozygously by nucleotide sequencing analysis in exon VII of the gene for the A subunit. The presence of this mutation was confirmed using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis in the proband and his brother. Molecular modelling predicts that the mutant molecule would be misfolded. It is probable that the impaired folding of the mutant Y283C A subunit led to its instability, which is at least in part responsible for the factor XIII deficiency of this patient.

Truncated mutant B subunit for factor XIII causes its deficiency due to impaired intracellular transportation

Two Japanese patients were newly diagnosed as having B subunit (XIIIB) deficiency of factor XIII (former type I deficiency). Both patients have a previously described one-base deletion at the boundary between intron A/exon II in the XIIIB gene, heterozygously or homozygously. A founder effect was proposed for this mutation because 3 unrelated patients with XIIIB deficiency also share 2 3'-polymorphisms. In one patient heterozygous for the above mutation, a novel mutation was also identified: a deletion of guanosine in exon IX (delG) of the XIIIB gene. To understand the molecular and cellular pathology of the delG mutation, expression studies were performed using a cultured mammalian cell line. Pulse-chase experiments showed that a resultant truncated XIIIB remained inside the cells and could not be secreted into the culture medium. Furthermore, immunocytochemical examinations by epifluorescence, confocal, and electron microscopes indicated impaired intracellular transportation of the truncated XIIIB from the endoplasmic reticulum to the Golgi apparatus. No mutations in the gene for the A subunit (XIIIA) were identified in this patient. Therefore, secretion of the truncated XIIIB must also be impaired in vivo, leading to a secondary XIIIA deficiency. These results support a previous conclusion that genetic defects of XIIIB are the basis for the former type I factor XIII deficiency.

Modulating effects of mucoregulating drugs on the attachment of Haemophilus influenzae

Non-typable Haemophilus influenzae (NTHI) is one of the three major pathogens implicated in human respiratory infections. The ability to attach with pharyngeal epithelial cells is an important factor for infection and virulence. In the present study we describe the effects of two mucoregulating drugs, S-carboxymethylcysteine (S-CMC) and ambroxol, on the attachment of NTHI to pharyngeal epithelial cells. There was a significant (P < 0.0001, < 0.001 and <0.01) decrease of attachment (8.8 +/ 2.4, 9.2+/-2.5 and 15.4 +/- 5.7 bactreria/cell) compared with the control (17.5 +/- 2.9, 15.5 +/- 3.1 and 18.8 +/- 6.8 bacteria/cell) after cells were treated wth S-CMC at a dose of 100, 10 and 1 microg/ml. After attachment assay, cells treated with S-CMC (100 microg/ml) showed a significant decrease (P < 0.01) of attached bacteria (3.1 +/- 0.8 bacteria/cell) compared with the control (5.9 +/- 1.8 bacteria/cell). Treatment of cells with ambroxol did not influence bacterial attachment. By scanning electron microscopic observation it was found that NTHI attaches to the surface elevations (microplicae) of human pharyngeal epithelial cells. Atomic force microscopic observation revealed that the surface potential of microplicae decreased significantly in cells treated with S-CMC compared with the untreated control cells. As bacteria with negative surface charge attach to the positively charged domain, i.e. microplicae of human pharyngeal epithelial cells, this study suggests that the decrease of attachment of NTHI with epithelial cells after treatment with S-CMC was possibly due to the decrease of surface charge. This study suggests that S-CMC decreases the episodes of respiratory infections in patients with respiratory diseases both by inhibiting the attachment of bacteria to the upper respiratory tract, and by detaching the adherent one.

Molecular and genetic mechanisms of factor XIII A subunit deficiency

Factor XIII is a proenzyme for a plasma transglutaminase. Factor XIII in plasma is a tetramer (A2B2) held together by noncovalent bonds, and the A subunit contains the active site. Recently, the three-dimensional structure of the A subunit has been determined by x-ray crystallography. To understand the structure-function relationships of the factor XIII molecule and its clinical implications in factor XIII deficiency, we characterized its genetic defects and closely examined its gene products, including mRNA and protein levels. A variety of missense and nonsense mutations (Arg260-Cys, Tyr283-Cys, Gly562-Arg) and deletions/insertions with or without out-of-frame shift/premature termination and splicing abnormalities (4-bp deletion with 464Stop, T insertion at the exon IV/intron D boundary with exon IV-skipping, 20-bp deletion at the exon I/intron A boundary) has been identified in cases demonstrating A subunit deficiency. In some cases, the A subunit mRNA levels were severely reduced. Their molecular and cellular bases have also been explored by expression experiments in mammalian cells and by molecular modeling. In most cases, impaired folding and/or conformational changes of the mutant A subunits lead to both intra- and extracellular instability, which is responsible for the A subunit deficiency in the patients.

Attachment of Moraxella catarrhalis occurs to the positively charged domains of pharyngeal epithelial cells

Attachment of bacteria to host cells is the initial step in the pathogenesis of infection. Several factors, such as hydrophobicity, surface electric charge, and van der Waals force, are considered to be responsible for the attachment step. However, it is not clear why bacteria and epithelial cells, both of which possess a negative surface charge, do not repel one another. In the present study, we used Moraxella catarrhalis and pharyngeal epithelial cells to study the surface charges of structures involved in the attachment. By atomic force microscopy (AFM) equipped with surface potential spectroscopy, it was found that the cell surface microplicae have a positive charge of 30.1+/-3.6 mV (mean+/-SE). The depressions between the microplicae have a negative surface charge of 43.5+/-4.0 mV. Using cationic ferritin and electron microscopy (EM) we confirmed that the depressions between the microplicae have a negative charge. By AFM and by using cationic ferritin with EM, it was found that the net surface charge of the bacterial cells is negative. By both AFM and EM, it was found that the bacterial cells attach to the microplicae of the pharyngeal epithelial cell. Our work confirmed the general belief that both kinds of cells do have a net negative charge. We conclude that there are positively and negatively charged domains on the surface of human pharyngeal epithelial cells. M. catarrhalis evidently attaches to the positively charged domain (i.e. microplicae) of pharyngeal epithelial cells.

Mesoporous Magnetic Materials Based on Rare Earth Oxides

A novel family of mesoporous oxides of rare earth metals (Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) were synthesized with specific surface areas of 253-348 m(2) g(-1) and pore diameters of 2.5-3.0 nm (see Scheme). The mesoporous solids and their surfactant mesophase precursors are paramagnetic and exhibit a magnetic anomaly due to the mesostructured atomic arrangement.

Common mutation of plasminogen detected in three Asian populations by an amplification refractory mutation system and rapid automated capillary electrophoresis

Congenital deficiency and dysfunction of plasminogen (PLG) are associated with a mild thrombotic tendency. To facilitate the genetic diagnosis of dysPLGemia, we combined an amplification refractory mutation system and rapid automated capillary electrophoresis. Two different fluorescence-labeled PLG-specific primers for exon XV were designed so that each DNA amplified by PCR showed fluorescence of a different wavelength. Single peaks were detected for the normal and the mutant Ala601 -Thr alleles, respectively. A study of 90 normal Caucasians revealed no individuals with the mutation, whereas its gene frequency was 0.021 in Japanese. This mutation was also detected in Korean and Chinese populations at gene frequencies of 0.016 and 0.015, respectively. All of the Korean and Chinese cases with the mutation had at least one haplotype I of the PLG gene, as did most Japanese cases. The high frequency of the Ala601-Thr mutation among these Asian populations may be due to the founder effect.

Transcriptional regulation of cell type-specific expression of the TATA-less A subunit gene for human coagulation factor XIII

To study the mechanism of gene regulation for coagulation factor XIII A subunit (FXIIIA), we characterized its 5'-flanking region using a monocytoid (U937), a megakaryocytoid (MEG-01), and other cells. Our results confirmed that U937 and MEG-01 contained FXIIIA mRNA. A tentative transcription start site was determined to be 76 bases upstream from the first exon/intron boundary. Reporter gene assays revealed that a 5'-fragment (-2331 to +75) was sufficient to support basal expression in U937 and MEG-01 but not in the other cells. Deletion analysis confined a minimal promoter sequence from -114 to +75. DNase footprinting, electrophoretic mobility shift, and reporter gene assays demonstrated that promoter elements for a myeloid-enriched transcription factor (MZF-1-like protein) and two ubiquitous transcription factors (NF-1 and SP-1) in this region were important for the basal FXIII expression. It was also revealed that an upstream region (-806 to -290) had enhancer activity in MEG-01 but silencer activity in U937. DNA sequences for binding of myeloid-enriched factors (GATA-1 and Ets-1) were recognized in this region, and the GATA-1 element was found to be responsible for the enhancer activity. These transcription factors play a major role in the cell type-specific expression of FXIIIA, which differs from other transglutaminases.

Identification of a flavivirus isolated from mosquitos in Chiang Mai Thailand

A virus isolate, ThCAr105/92, from a pool of mosquitos, Culex tritaeniorhynchus, collected in Chiang Mai, Thailand in 1992, appeared to be a member of the genus Flavivirus of the family Flaviviridae, based on the reverse transcription polymerase chain reaction (RT-PCR) using flavivirus cross-reacting primer pairs, electron microscopic examination, and serological tests. However, RT-PCR using Japanese encephalitis (JE) virus-specific primers showed that the isolate was different from JE virus. Sucrose density gradient sedimentation of the virus replicated in C6/36 cells indicated that the virus is relatively unstable in the infected culture fluids at 37 degrees C. Antibody prepared against this virus and a virus seed for the isolate were tested by cross neutralization against a panel of flaviviruses and the results showed that the new isolate was a distinct subtype of Tembusu virus.

Expression of plasminogen-related gene B varies among normal tissues and increases in cancer tissues

We previously found that the promoter activity of plasminogen (PLG)-related gene B (PRGB) was 5-fold that of PLG. We have since examined the transcript levels of PRGB among various normal human tissues, and compared these findings with those of PLG. Reverse transcription-PCR analysis revealed that the PRGB expression varied widely among different tissues, while PLG was expressed only in the liver and kidney. RNA samples obtained from cultured cell lines also demonstrated differing PRGB expression. Furthermore, increased PRGB expression was observed in several fresh samples of cancer tissue obtained from cancer patients when compared with surrounding normal tissues.

Anatomical and neurochemical peculiarities of the pika retina: basis for lack of circadian rhythm of core temperature

We have previously reported a complete lack of circadian rhythm in the body temperature of pikas in contrast to other lagomorphs. In this present study, the anatomical and neurochemical findings by immunohistochemical, photo and electron microscopic methods reveal that the photoreceptor system of this animal is poorly developed. This probably explains their stable core body temperature which help them survive in cold temperatures.

[Molecular patho-biochemistry and genetic diagnosis for plasminogen-apolipoprotein (a) gene family related to atherosclerosis and thrombosis]

Plasminogen is a key proenzyme of plasmin in the fibrinolytic and thrombolytic systems, the deficiency of which leads to a mild thrombotic tendency. Plasminogen binds to fibrin as well as to the surface of endothelial cells and monocytes/macrophages, where it is activated to plasmin. Individuals with dysplasminogenemia were analyzed by a combination of PCR and restriction digestion. Among 125 unrelated families, an Ala601-Thr mutation accounted for about 94% of cases, while a Val355-Phe mutation was found in four unrelated families. A new mutation, Asp676-Asn, has been identified in two cases. To facilitate the rapid genetic diagnosis of dysplasminogenemia, we also developed a method that combines an amplification refractory mutation system and rapid automated capillary electrophoresis. Apolipoprotein(a) [apo(a)] is a protein component of lipoprotein(a), high plasma levels of which constitute a risk factor for atherosclerotic thromboembolic disease. Since apo(a) is very similar to plasminogen in terms of amino acid sequence, it inhibits plasmin generation by competing with plasminogen's binding to fibrin and endothelial cells. Although the plasma Lp(a) concentration roughly correlates with the size and number of Kringle 4 repeats of apo(a), a significant variation in the Lp(a) level exists among individuals having the same inform. We subclassified the apo(a) gene into four types (A-D) by polymorphisms in its 5'-flanking region. We also measured plasma Lp(a) concentrations in vivo and examined expression of the gene by in vitro assay. Homozygotes of type C had higher Lp(a) levels than those of type D, and the relative expression of type C was higher than that of type D in vitro. Thus, Lp(a) concentrations in human plasma are predetermined at the genetic level by extensive polymorphisms in both the 5'-alleles and the numbers of Kringle 4 repeats.