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Biomedical subjects

M C Lo

Publications and source records attributed to M C Lo.

At least 19 recordsLinked to original sources
PubMed2001

Characterization of a fucose-binding protein from bull sperm and seminal plasma that may be responsible for formation of the oviductal sperm reservoir.

Oviductal sperm reservoirs have been found in cattle, mice, hamsters, pigs, and horses. In cattle (Bos taurus), the reservoir is evidently formed when sperm bind to fucosylated ligands resembling Le(a) trisaccharide on the surface of oviductal epithelium. The aim of this study was to characterize the fucose-binding protein on bull sperm. Fresh ejaculated sperm were extracted with 0.5 M KCl in Hepes-balanced salts. Extracts were subjected to affinity chromatography using immobilized Le(a) trisaccharide (alpha-L-Fuc[1,4]-beta-D-Gal[1,3]-D-GlcNAc). Two-dimensional PAGE of the affinity chromatography eluates revealed a prominent protein of approximately 16.5 kDa and a pI of 5.8. This protein inhibited binding of sperm to oviductal explants. A similar analysis of proteins extracted from capacitated sperm (which do not bind to oviductal epithelium) showed a reduction in the amount of the 16.5-kDa protein. When examined by epifluorescence microscopy, live uncapacitated sperm labeled over the acrosome with a fucose-BSA-fluorescein isothiocyanate (FITC) conjugate, while capacitated sperm did not. When capacitated sperm were treated with 16.5-kDa protein, labeling with fucose-BSA-FITC was partially restored. The comparative ease with which the protein was removed from sperm and its apparent reassociation with sperm suggested that it could be a peripheral protein derived from epididymal or accessory gland fluids. Blots of SDS-PAGE gels of seminal plasma proteins revealed the presence of a Le(a)-binding protein with an apparent mass of 16.5 kDA: Amino acid sequencing of two tryptic fragments of the protein purified from sperm extracts identified it as PDC-109 (BSP-A1/A2), a product of the seminal vesicles.

Acrosome↗
PubMed2001

Infective endocarditis with neurologic complications: 10-year experience.

The impact of neurologic complications on clinical outcomes in infective endocarditis was assessed. Medical records of patients with infective endocarditis from January 1, 1987 through September 30,1998 were analyzed. Patients were divided into two groups: one with neurological complications and the other without. The outcomes of the two groups were compared using Fisher's exact test. Fifty-eight patients fulfilled the definite Duke criteria. There were 46 men and 12 women, ranging from 3 to 71 years of age with a mean of 40.6 years. Pathogens of infective endocarditis were documented by blood culture in 55 (94.8%) of 58 patients as follows: 52 with gram-positive cocci, two with gram-negative bacilli, and one with fungus. All 58 patients had initially received antimicrobial agents. Eight (13.8%) of the 58 patients had received surgical valvular replacement because of medical treatment failure. Overall, 16 (27.6%) of 58 patients died. Neurologic complications were either the chief complaint or one of the major presenting symptoms in 16 (27.6%) of the 58 patients. Patients with neurologic complications had a higher mortality rate (50% vs 20.9%, p = 0.025) than those without neurologic complications. The adjusted risk ratio for neurologic complications for a fatal event was 3.51 (95% CI = 1.1-11.18, p = 0.03). Neurologic complications pose a significant problem in infective endocarditis. To reduce mortality, we recommend that more attention be paid to the treatment and prevention of the neurologic complications of infective endocarditis.

Adolescent↗
PubMed1999

Comparison of treatment outcomes for imipramine for female genuine stress incontinence.

OBJECTIVE: To assess the efficacy of imipramine as a treatment of genuine stress incontinence and to explore the possible determining factors for treatment success and failure. DESIGN: A prospective study. SETTING: University department of obstetrics and gynaecology. PARTICIPANTS: Forty women with genuine stress incontinence were enrolled. METHODS: Each woman was treated with 25 mg imipramine three times a day for three months. MAIN OUTCOME MEASURES: Each woman had a 20-minute pad test and urodynamic study including uroflowmetry, both filling and voiding cystometry, and stress urethral pressure profile before and after treatment. RESULTS: After treatment, 35% (n = 14) were cured, 25% (n = 10) improved by > or = 50% and in the remaining 40% (n = 16) treatment failed. The efficacy of successful treatment was 60% (95% CI 44.8-75.2). The median age and parity, as well as menopausal status, showed no statistical differences between the two groups. The pre-treatment data including pad weight, functional urethral length, maximal urethral pressure, bladder compliance at urgency, bladder capacity, and average and maximal flow rates showed no statistical differences between the two groups except urethral closure pressure (P = 0.001). Besides, the functional urethral length and urethral closure pressure were significantly improved in the treatment success group. After medication, the median functional urethral length was 3 cm (intraquantile range [IQR] 2.3-3) in the treatment success group vs 2.3 cm (IQR 2-3) in the treatment failure group (P = 0.028). The urethral closure pressure was 77 cmH2O (IQR 61-105) for the treatment success group vs 40 cmH2O (IQR 34-53) in the treatment failure group (P < 0.0001). CONCLUSIONS: The efficacy of imipramine for genuine stress incontinence was 60% (95% CI 44.8-75.2). The pre-treatment high urethral closure pressure may serve as a predictor for treatment success.

Adrenergic Uptake Inhibitors↗
PubMed1998

Role of M-line proteins in sarcomeric titin assembly during cardiac myofibrillogenesis.

A rat polyclonal anti-M-line protein antiserum and three mouse monoclonal anti-titin antibodies (E2, F3, and A12) were used to study the spatiotemporal relationship between M-line proteins and titin during myofibril assembly in cultured chicken cardiomyocytes by immunofluorescence microscopy. In day 2 cultures, M-line proteins and titin were detected as punctate staining in most cardiomyocytes, which possessed many nonstriated fibrils. At a late stage (day 3 cultures), M-line proteins were incorporated into dot-like structures along nonstriated fibrils, while titin staining was continuous on these structures. As development progressed, M-line proteins were registered in periodic pattern in the mid-A band. In cardiomyocytes from day 5 cultures, the titin bands were separated by an unstained region, and achieved their adult doublet pattern. Thus, the organization of titin in the sarcomere appears to occur later than that of M-line proteins in the M-line. Our morphological data indicate that the early registration of M-line proteins in primitive myofibrils may guide titin filament alignment via interaction between M-line proteins and titin. In order to investigate the role of M-line proteins in the assembly of titin filaments, anti-M-line protein or anti-titin antibodies were introduced into cultured cardiomyocytes by electroporation to functionally bind the respective proteins, and the profile of myofibril assembly was examined. Cardiomyocytes from day 2-3 cultures with incorporated anti-M-line protein antibodies became shrunk, and exhibited defective myofibrillar assembly, as shown by the failure of titin to assemble into a typical sarcomeric pattern. Incorporation of anti-titin antibody E2, which recognizes the M-line end domain of titin, resulted in the failure of M-line proteins organized into the M-line structure, as shown by random, sporadic staining with anti-M-line protein antibody. These studies confirm the essential role of M-line proteins in the organization of titin filaments in the sarcomere and that the interaction between titin and M-line proteins is crucial to the formation of the M-line structure.

Animals↗
PubMed1998

The solution structure of the DNA-binding domain of Skn-1.

Skn-1 is a maternally expressed transcription factor that specifies the fate of certain blastomeres early in the development of Caenorhabditis elegans. It has been reported that the DNA-binding domain is a molten globule and that the structure cannot be defined because there are no long-range nuclear Overhauser effects (NOEs). Working with short Skn domain fragments and using 13C-labeled proteins, we have been able to identify 28 long-range NOEs that establish a tertiary fold for the Skn domain. The internal region of the Skn domain consists of three stable helices and one conformationally labile helix organized into a nascent helix-turn-helix-turn-helix-turn-helix motif. The N and C termini of the Skn domain are unstructured and emerge from the same end of the folded domain. This structure is consistent with biochemical data on binding of the Skn domain to DNA, which shows that the N and C termini bind in the adjacent minor and major grooves from the same face of the DNA helix. The NMR solution structure of the Skn domain should be useful for developing a complete understanding of the DNA recognition event, including any conformational changes that take place upon binding.

Amino Acid Sequence↗
PubMed1998

Mutation analysis of Wilson disease in Taiwan and description of six new mutations.

Wilson disease is an autosomal recessive disorder of copper metabolism. Mutation screening in Wilson disease has led to the detection of at least 89 disease-specific mutations. Some mutations appear to be population specific, while others are common to many populations. In this study, 38 Taiwanese patients with Wilson disease were screened using single-strand conformation polymorphism analysis, followed by direct DNA sequencing. We found 12 different mutations, six of which were novel. All our detected mutations were found to be in eight exons. Four mutations in three loci (Arg778Gln, Arg778Leu, Gly943Asp, and Pro992Leu) accounted for about 58% of the mutant alleles we detected. Using an RNA transcriptional assay, we confirmed that both of our detected splice-site mutations resulted in exon skipping.

Alleles↗
PubMed1998

Abnormal urodynamic findings after radical hysterectomy or pelvic irradiation for cervical cancer.

OBJECTIVE: To assess urodynamic study results in patients with cervical cancer who had received radical hysterectomy or pelvic irradiation or radical hysterectomy with pelvic irradiation. METHODS: Forty-two patients with stage IB cervical cancer after radical hysterectomy (group A), 11 patients at stage IB or IIA after pelvic irradiation (group B), 15 patients at stage IB or IIA after both radical hysterectomy and pelvic irradiation (group C) and 17 patients at stage IB before treatment (group D) as control were recruited for urodynamic examination. The evaluations for each case included a 20-min pad test, uroflowmetry, both filling and voiding cystometry, and stress urethral pressure profile. ANOVA method with Bonferroni test and Pearson chi2-test were utilized for statistical analysis. RESULTS: The mean ages in sequential groups A, B, C and D were 52.9 +/- 10.2, 62.5 +/- 13.5, 49.8 +/- 11.7 and 49.4 +/- 12.5 years (P = 0.02), respectively. The occurring frequency of either detrusor instability or low bladder compliance was 57%, 45%, 80% and 24%, respectively. Each group revealed decreased bladder capacity as 268.4 +/- 102.8, 164.1 +/- 62.9, 233.5 +/- 73.9 and 293.0 +/- 47.2 ml (P < 0.0001). However, the frequency of abdominal strain voiding was 100% in groups A, B and C as compared to 0% in group D (P < 0.01), and the frequency of abnormal residual urine (> 50 ml) was 41%, 27%, 40% and 24%. Although each case showed a poor pressure transmission ratio (< 100%), the frequency of positive pad test in each group was 81%, 46%, 100% and 18% (P < 0.001). The functional urethral length decreased in each group and was 2.6 +/- 0.8, 2.3 +/- 0.8, 2.5 +/- 0.8 and 2.9 +/- 0.6 cm, but there were no significant differences in maximal urethral pressure or urethral closure pressure among the four groups. CONCLUSIONS: Our data show that abnormal urodynamic findings pre-exist in patients with cervical cancer before treatment especially in bladder storing function, and that these findings may worsen, or that new abnormal findings may happen after radical hysterectomy or pelvic irradiation, or both.

Combined Modality Therapy↗
PubMed1998

Rapid detection of a recombinant hotspot associated with Charcot-Marie-Tooth disease type IA duplication by a PCR-based DNA test.

A 1.5-Mb duplication on chromosome 17p11.2-p12 (CMT1A duplication) caused by a misalignment of the CMT1A repeat sequences (CMT1A-REPs) is associated with Charcot-Marie-Tooth disease type 1A (CMT1A). A hotspot of crossover breakpoints located in a 3.2-kb region of the CMT1A-REPs accounts for three-quarters of the rearrangements in CMT1A patients. We developed a PCR-based diagnostic method to detect a recombination hotspot associated with the CMT1A duplication. Thirty-one CMT1A Chinese patients from different families and 50 healthy people over 65 years of age were studied. Twenty-seven of the 31 cases demonstrated the 3.2-kb hotspot crossover, of which there were two subgroups. The type 1 crossover breakpoint was located at the distal CMT1A-REP around the PmeI site, and accounted for 24 of the 27 cases with a 3.2-kb hotspot crossover in CMT1A duplication patients. The type 2 crossover breakpoint was located at the distal CMT1A-REP around the base 3625 region, accounting for 3 of the 27 cases. The results correlated very well with the results of Southern transfer analysis. This study has a potentially important role in the diagnosis of CMT1A disease.

Charcot-Marie-Tooth Disease↗
PubMed1997

Skn-1: evidence for a bipartite recognition helix in DNA binding.

Skn-1 is a maternally expressed transcription factor that specifies the fate of certain blastomeres early in the development of Caenorhabditis elegans. This transcription factor contains a basic region, but it binds to DNA as a monomer. Because other transcription factors containing basic regions bind as dimers, this finding implied that Skn represents a new DNA recognition motif. It has been proposed that the basic region helix of Skn is stabilized for binding by tertiary contacts to other parts of the protein. We have tested this proposal by carrying out circular dichroism (CD) and NMR experiments on the Skn domain and five truncated proteins. Our results have shown that the basic region of Skn is unstructured in solution and does not contact other parts of the protein; like other basic region peptides, it folds into a helix only upon binding specifically to DNA. However, there is a stably folded helical module in the Skn domain, and one of the helices in this module terminates immediately before the start of the basic region. This pre-organized helix contains a surface rich in basic amino acids, and we propose that this helix contacts the DNA distal to the basic region proper, providing an extra long helical recognition surface which helps to stabilize monomeric binding. Homology between the Skn domain and several basic-region leucine zipper (bZIP) domains raises the possibility that the affinity and perhaps the specificity of DNA binding by bZIP proteins can be modulated by incorporating a stably folded helical segment that contacts the DNA just below the basic region proper.

Amino Acid Sequence↗
PubMed1997

Bovine sperm binding to oviductal epithelium involves fucose recognition.

Sperm binding to oviductal epithelium probably serves to form the isthmic sperm reservoir. This interaction of sperm and oviductal epithelium may involve species-specific carbohydrate recognition. We tested a series of carbohydrates and glycoproteins for inhibition of bovine sperm binding to oviductal epithelium in vitro. Explants of isthmic and ampullar epithelium were obtained from oviducts that had been surgically removed from preovulatory heifers. The explants were incubated (39 degrees C, 5% CO2) with fetuin, asialofetuin, ovalbumin, fucoidan, fucose, N-acetyl glucosamine, or N-acetyl glucosamine sulfate dissolved in a modified Tyrode's balanced salt solution, termed sperm-TALP (pH 7.4, 295 mOsm) for 10 min before frozen-thawed motile sperm obtained by swim-up were added. After 15 min, the explants were rinsed, and sperm binding density was evaluated. Oviductal explants treated with fucoidan (3 mg/ml; p < 0.001, n = 5) or fucose (31 mM, p < 0.01, n = 6) had reduced densities of bound sperm compared to the controls. Incubation of explants in increasing concentrations of fucose (4-62 mM) resulted in increased inhibition of sperm binding. Pretreating explants with fucosidase also reduced sperm binding (p < 0.001, n = 3) compared to that in controls containing the fucosidase inhibitor deoxyfuconojirimycin. The presence of fucosylated molecules on the surface of the oviductal epithelium was confirmed by labeling with fucose lectins from Ulex europeus and Lotus tetragonolobus. We conclude that fucose is involved in a specific interaction between bovine sperm and oviductal epithelium.

Animals↗
PubMed1991

Two new isolates of Bacillus thuringiensis pathogenic to Spodoptera litura.

Both the standard Bacillus thuringiensis kurstaki (HD-1) and the formulated commercial product resulted from this strain have shown limited pathogenicity against the tobacco cutworm (Spodoptera litura). However, two new isolates of Bacillus thuringiensis (K-2074 and K-2178) isolated from Taiwan have been identified through an active screening program to be highly pathogenic against the tobacco cutworm. In this paper, we present results of characterization and the pathogenicity of these two new isolates.

Animals↗
PubMed1990

Characterization of filamentous bacteriophage phi Lf from Xanthomonas campestris pv. campestris.

A filamentous phage, phi Lf, which specifically infects Xanthomonas campestris pv. campestris was isolated. The phage particle measured 1,000 (+/- 200) x 8 nm. It formed turbid plaques of about 1 mm in diameter. During multiplication, the progeny virions extruded into the medium without retarding host cell growth. Stocks were stable for 6 months at 4 degrees C and survived treatment at 80 degrees C for 10 min. Treatment with chloroform, ethanol or acetone completely destroyed infectivity; ethyl ether and methanol inactivated 98 to 99% of the phage. SDS-polyacrylamide gel electrophoresis showed a major coat protein band of approximate Mr 4000 whereas an immunoprecipitation test detected the existence of two coat protein species. The phage genome was shown to be a single-stranded DNA molecule. A physical map was constructed and the DNA size was calculated to be 5.9 kb. Cells treated with Tris-HCl containing CaCl2 and polyethylene glycol 6000 were transfected by replicative form DNA at a frequency of 3.4 x 10(3) p.f.u./micrograms.

Bacteriophages↗
PubMed1978

Metastatic prostatic adenocarcinoma of male breast.

Three cases of metastatic adenocarcinoma of the male breast from prostatic carcinoma are added to the 15 well-documented cases reported in the literature. These 15 cases had received estrogen therapy for prostatic cancer and gynecomastia developed; 14 had clinically palpable breast nodules containing adenocarcinoma. Our 3 cases also received estrogen therapy but differed in that gynecomastia developed in only 1 patient clinically, and diagnoses were made at autopsy with no clinical symptoms related to breast metastases. Moreover, 1 cases also showed remarkable florid lactation-like changes of the breast almost indistinguishable morphologically from that seen in the female breast during pregnancy. The histopathologic differential diagnosis of metastatic prostatic carcinoma of the breast from primary cancer of the male breast is stressed. Its importance is obvious because of the differences in clinical treatment and prognosis. Microscopically, the differential points consist of duct hypertrophy and periductal fibrosis (gynecomastia), absence of any ductal involvement by carcinoma cells, frequent presence of cancer cells in lymphatics and vascular channels, morphologic similarity between the cancers in the breast and prostate, and finally, the usual presence of acid phosphatase in the tumors of the prostate and breast.

Adenocarcinoma↗