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Biomedical subjects

T T Kuo

Publications and source records attributed to T T Kuo.

At least 37 records · Page 2Linked to original sources
PubMed1999

A variant of Saccharomyces cerevisiae pep4 strain with improved oligotrophic proliferation, cell survival and heterologous secretion of alpha-amylase.

A variant of Saccharomyces cerevisiae pep4 strain 20B12, with improved oligotrophic proliferation, cell survival and secretion of heterologous mouse alpha-amylase, is described. Previously we reported a procedure to enrich NI transformants that are not inhibited by cytotoxic expression of hepatitis B virus surface antigen in the secretion pathway of the protease-A-deficient (pep4) strain. To use the NI cells as a host for heterologous expression, we tried to amend the introduced pYAS/12S vector and obtain a host strain, NI-C, with stable NI phenotype and trp1 marker restored. Southern analysis of genomic DNA of NI-C suggested that the original pYAS/12S was abnormally rearranged and not completely corrected. Further assay showed that the viability and mitotic ability of the NI-C strain were increased. While using the NI-C strain as host for plasmid transformation and heterologous expression of mouse alpha-amylase, we observed that transformed colonies grew more quickly and secreted more alpha-amylase than general yeast strains. A further test showed that the NI-C strain was able to use mouse alpha-amylase as a positive selection marker to form transformed colonies on nitrogen-starved plates that contain starch as the sole carbon source. The results imply that the NI-C variant is an improved pep4 strain that can be used for heterologous expression and for the development of new selective markers in the yeast transformation system.

Animals↗
PubMed1999

The pilA gene of Xanthomonas campestris pv. citri is required for infection by the filamentous phage cf.

Host factors that are important for infection of Xanthomonas campestris pv. citri by the filamentous bacteriophage cf were investigated by transposon mutagenesis with Tn5tac1. A mutant, XT501, that was resistant to cf infection was recovered, showing that the gene inactivated by the transposon is required for infection by the phage but not for cf replication or assembly. A 1.7-kb SacI-ApaI DNA fragment from XT501 containing the bacterial DNA flanking one end of the transposon was cloned and shown to be required for cf infection. Nucleotide sequence analysis of the 1.7-kb fragment reveals the presence of an ORF that encodes a protein of 146 amino acids. This protein shows 42% identity to the type 4 prepilin encoded by the pilA genes of other bacteria. The pilA gene of X. campestris pv. citri is thus essential for infection by the bacteriophage cf.

Amino Acid Sequence↗
PubMed1999

Requirement for phosphoglucose isomerase of Xanthomonas campestris in pathogenesis of citrus canker.

A mutant (XT906) of Xanthomonas campestris pv. citri, the causal agent of citrus canker, was induced by insertion of the transposon Tn5tac1 and isolated. This mutant did not grow or elicit canker disease in citrus leaves but was still able to induce a hypersensitive response in a nonhost plant (the common bean). The mutant was also unable to grow on minimal medium containing fructose or glycerol as the sole carbon source. A 2.5-kb fragment of wild-type DNA that complemented the mutant phenotype of XT906 was isolated. Sequence analysis revealed that this DNA fragment encoded a protein of 562 amino acids that shows homology to phosphoglucose isomerase (PGI). Enzyme activity assay confirmed that the encoded protein possesses PGI activity. Analysis of the activity of the promoter of the pgi gene revealed that it was inhibited by growth in complex medium but induced by culture in plant extract. These results demonstrate that PGI is required for pathogenicity of X. campestris pv. citri.

Citrus↗
PubMed1998

Disassociation of sigma subunit from RNA polymerase of Xanthomonas oryzae pv. oryzae by phage Xp10 infection.

The sigma subunit of Xanthomonas oryzae pv. oryzae is disassociated from host RNA polymerase after phage Xp10 infection. To clarify the possible mechanism for this observation, sigma subunit was purified and an antiserum against sigma subunit was prepared. Immunoprecipitation of RNA polymerase by the anti-core RNA polymerase antiserum, followed by immunoblotting with anti-sigma subunit antibody, revealed that sigma subunit was lost from RNA polymerase within 10 minutes after Xp10 infection. Loss of sigma subunit was not observed under other stress conditions including heat and cold stress, starvation and growth to stationary phase. Two-dimensional immunoblotting analysis did not reveal any covalent modification of either sigma subunit or RNA polymerase after Xp10 infection. These results suggest that separation of th subunit from RNA polymerase may be due to competition with other binding factors.

Antibodies, Bacterial↗
PubMed1998

Keloidal dermatofibroma: report of 10 cases of a new variant.

Dermatofibroma is a common cutaneous tumor. Unusual variants of dermatofibroma that exhibit various epidermal changes or different cellular composition have been described. We observed 10 cases of a novel variant of dermatofibroma characterized by keloidal change within the tumor. Formalin-fixed, paraffin-embedded tissues were used for histochemical and immunohistochemical studies. The patients consisted of six women and four men; median age was 34 years (17 to 59 years). All tumors occurred on the extremities, and six were present for at least 2 years. Tenderness was mentioned in four cases. They were described as erythematous or brown papules 1 cm or smaller. Clinical appearance did not deviate from that of ordinary dermatofibromas. Microscopically, the excised tumors showed a superficial circumscribed area of keloidal change under an atrophic epidermis in an otherwise ordinary dermatofibroma. In the keloidlike area, multinucleated giant cells, hemorrhage, hemosiderin deposits, and scattered KiM1P-positive histiocytes, but not factor XIIIa-positive or CD34-positive cells were present among the thick collagen fibers. There were no known recurrences. This variant dermatofibroma should not be overlooked as a simple keloidal scar. The observation of keloidal change in dermatofibromas may support the connotation that trauma is a possible cause of dermatofibroma. The fact that Asian people are more prone to develop keloid may have led us to find this new variant.

Adolescent↗
PubMed1998

Thymic carcinoma arising in thymoma is associated with alterations in immunohistochemical profile.

Thymic carcinoma is an uncommon tumor. Most cases appear to arise de novo, but in rare instances they can arise in thymomas. We report the clinicopathologic features and immunohistochemical profile of five cases of thymic carcinoma accompanied by a component of thymoma. Immunohistochemical studies were performed with the avidin-biotin-peroxidase complex method using monoclonal antibodies to p53(DO7), CD99(O13), epithelial membrane antigen, CD5(NCL-CD5-4C7), vimentin (V9), and cytokeratins 7, 8, 18, and 19. The patients consisted of three men and two women with a median age of 57 years. One patient had myasthenia gravis, and the other four presented with chest symptoms. One patient had concurrent adenocarcinoma of the lung with metastasis. Four of the patients died within 15 months. The thymomas consisted of two large polygonal cell thymomas, two squamoid thymomas, and one spindle cell thymoma. The malignant components included two undifferentiated carcinomas, one spindle cell carcinoma, one squamous cell carcinoma, and one clear cell carcinoma with squamous differentiation. There was no correlation between the histologic types of the thymoma and the thymic carcinoma. In three cases, excluding the two squamoid thymomas, the thymic carcinomas occurred in the necrotic areas of the thymoma. They showed upregulated expression of epithelial membrane antigen and cytokeratins 7, 8, 18, and 19, similar to the so-called "interface phenomenon" described in the invasion front of other types of carcinoma. Increased p53 protein expression was observed in all five carcinomas, and there was loss of CD99+ immature T lymphocytes. Among the thymic carcinomas, only the squamous component of the clear-cell carcinoma stained for CD5, a marker commonly expressed in thymic carcinomas. Paradoxically, a squamoid thymoma, but not its associated spindle cell carcinoma, expressed CD5, suggesting the acquisition of an "aggressive" phenotype by the squamoid thymoma, but with loss of the marker on malignant transformation. One undifferentiated carcinoma acquired vimentin immunoreactivity, whereas four other carcinomas and all five thymomas were negative. In conclusion, thymic carcinoma can arise in any histologic type of thymoma, including spindle cell thymoma, which is generally regarded as a benign neoplasm. The prognosis appears to be poor. Tumor necrosis in a thymoma should alert the pathologist to search for malignant change. The malignant change is commonly associated with increased expression of epithelial membrane antigen, cytokeratin subtypes, or p53 protein, and loss of CD99+ immature T lymphocytes, and is occasionally associated with a change in the expression of CD5 or vimentin.

Adult↗
PubMed1998

Granulocytic sarcoma presenting as a giant breast tumor in a pregnant woman: a case report.

We report a case of granulocytic sarcoma (chloroma) presenting as a giant breast tumor in a pregnant woman with no history of leukemia. The case was initially diagnosed as medullary carcinoma on a biopsy specimen and a modified radical mastectomy was performed. The diagnosis of granulocytic sarcoma requires the pathologist's high index of suspicion. The presence of immature eosinophils was an important clue. Leder's chloroacetate esterase stain; immunostaining for myeloperoxidase, CD34, CD43, CD68, and lysozyme; and ultrastructural finding of cytoplasmic lysosomal granules and Auer bodies all aided in confirming the diagnosis. It is imperative to recognize granulocytic sarcoma to avoid unnecessary surgery. Granulocytic sarcoma should be included in the differential diagnosis of breast tumors, especially in tumors with diffuse proliferation of small tumor cells.

Adult↗
PubMed1998

Congenital malignant rhabdoid tumor presenting as a cutaneous nodule: report of 2 cases with review of the literature.

OBJECTIVE: The congenital occurrence of malignant rhabdoid tumor (MRT) is rare. Initial presentation of congenital MRT as a skin tumor is even more rare. We report 2 cases in which a cutaneous nodule appeared prior to the discovery of the primary tumor. METHODS: Histologic, ultrastructural, and immunohistochemical studies were performed on skin nodules from 2 neonates. Other congenital examples of MRT in the literature were reviewed. RESULTS: Both neonates were male and both were fullterm. Skin nodules were noted at birth. The tumors were located on the right neck in case 1 and on the right back in case 2. The primary tumors were later found in the kidney and the right chest wall, respectively. The skin biopsy of the first case had been interpreted as undifferentiated sarcoma, and MRT was diagnosed after the renal tumor was examined. In the second case, a correct diagnosis was promptly made based on the skin biopsy owing to experience with the first case. CONCLUSIONS: Congenital MRT is very uncommon and may present as a skin tumor at birth. Since MRT exhibits various histologic patterns, the diagnosis should be made by a complete pathologic study with proper clinical correlation. To our knowledge, the unique mode of manifestation in these 2 cases is described for the first time. We suggest that MRT should be considered when making the differential diagnosis in such a clinical setting.

Biomarkers, Tumor↗
PubMed1997

p53 expression and proliferative activity in Bowen's disease with or without chronic arsenic exposure.

A comparative study of Bowen's disease (BD) with or without chronic arsenic exposure may contribute to understanding arsenic carcinogenesis. We compared the p53 overexpression and proliferative activity of 26 cases of BD with chronic arsenic exposure (group I) and 22 comparable cases of BD without chronic arsenic exposure (group II) by immunohistochemical method on formalin-fixed, paraffin-embedded tissues with antibodies PAb1801 and MIB-1, respectively. We also included in this study two squamous cell carcinomas that developed from BD in group I and one in group II. Two paired BD lesions in the same individual of one patient in group I and of three patients in group II were also studied. The significant p53(+) (>10% stained cells) rates were 42.3% (11 of 26) and 9.1% (2 of 22) for groups I and II, respectively, and the difference was statistically significant (P = .01). The p53 expression in different lesions of the same individual remained consistently the same. Squamous cell carcinomas that developed in 2 cases of p53(+) BD in group I were also positive, but the one in 1 case of p53(-) BD in group II was negative. No significant statistical difference in proliferative activity was found between group I BD and group II BD (P= .769), nor between p53(+) cases (>10% stained cells) and p53(-) cases (<10% stained cells) in group I BD (P = .519). This study showed that significant overexpression of p53 protein was higher in BD with chronic arsenic exposure. Therefore, arsenic carcinogenesis of BD might be different from that of BD unrelated to arsenic, and alteration of p53 plays a more important role in the pathogenesis of BD with chronic arsenic exposure. Overexpression of p53 was not a prerequisite for developing squamous cell carcinoma and was not affected by proliferative activity.

Adult↗
PubMed1997

Simultaneous occurrence of papulonecrotic tuberculide and erythema induratum and the identification of Mycobacterium tuberculosis DNA by polymerase chain reaction.

The simultaneous occurrence of two tuberculides in one patient is rare. We report the case of a 32-year-old man presenting with both papulonecrotic tuberculide and erythema induratum. Mycobacterial DNA was identified from both skin lesions by polymerase chain reaction using formalin-fixed and paraffin-embedded tissues, suggesting that tuberculides are related to tuberculosis. New skin lesions developed after the patient discontinued his medication on his own initiative, 2 months after triple antituberculous therapy had been started. It is important to continue therapy for a prolonged period.

Adult↗
PubMed1997

Cutaneous involvement in polyvinylpyrrolidone storage disease: a clinicopathologic study of five patients, including two patients with severe anemia.

Polyvinylpyrrolidone (PVP), formerly a plasma expander, has continued to be inappropriately used in Taiwan for intravenous injection as a "blood tonic." Five cases of PVP storage disease with cutaneous involvement were studied. Two patients presented with cutaneous eruptions mimicking collagen vascular disease and chronic pigmented purpuric dermatosis. Two other cases were found incidentally: one was with a metastatic tumor and the other in a pemphigus lesion. The fifth case was seen in a blind skin biopsy specimen taken to exclude Niemann-Pick disease after hematologic examination of a bone marrow smear. The latter patient and the patient with a collagen vascularlike disease also had severe anemia and serious orthopedic and neurologic complications due to massive infiltration of PVP-containing cells in the bone marrow with destruction of the bone. Severe irreversible anemia due to PVP storage disease has not been reported before. Three patients admitted having a history of receiving intravenous injection of PVP. The samples obtained from two of them indeed contained 5% PVP as determined by chemical analysis. PVP storage disease can be diagnosed by its histopathologic features. The skin biopsy specimens all showed a variable number of characteristic blue-gray vacuolated cells around blood vessels and adnexal structures with positive tinctorial reactions to mucicarmine, colloidal iron, and alkaline Congo red and negative to periodic acid-Schiff (PAS) and alcian blue. The PVP storage cells were shown to be CD68+ macrophages. The presence of PVP in the skin induced little or no inflammatory reaction. Only the pelvic mass in one patient had a foreign body granuloma formation. Our study showed that systemic parenteral administration of PVP preparation could result in the accumulation of PVP storage cells in the skin, with or without clinical eruptions. The diagnosis of systemic PVP storage disease can be established by performing a skin biopsy for pathologic study. It is important for pathologists and clinicians to be aware of this iatrogenic storage disease to avoid misdiagnosis for hereditary storage disease, osteomyelitis, or signet-ring cell carcinoma. Serious hematologic and orthopedic complications can be caused by repeated massive intravenous injection of PVP. Therefore, PVP preparations should be strictly prohibited for systemic administration.

Adult↗
PubMed1997

Novel and frequent mutations of hepatitis B virus coincide with a major histocompatibility complex class I-restricted T-cell epitope of the surface antigen.

We examined the full-length hepatitis B virus (HBV) envelope (surface antigen or HBV small surface antigen [HBsAg]) sequences of 12 different liver samples from 10 different hepatoma-containing chronic carriers. Surprisingly, novel and frequent mutations occurred predominantly at amino acids 40 and 47 of HBsAg, in addition to within a known protective B-cell epitope (so-called group a determinant of HBsAg 124-148). Approximately 58% of chronic carriers contain mutations at the group a determinant. The mutation frequency at the hotspot codons 40 and 47 is approximately 83%, 1 order of magnitude higher than at the known polymorphic sites of subtype-specific determinants at codons 122 and 160, which is approximately 4%. This new mutational domain is found to coincide with a major histocompatibility complex class I-restricted T-cell epitope. The potential biological significance of this novel mutation in the immunopathogenesis of HBV chronic carriers is discussed.

Adult↗
PubMed1997

Leukemia cutis as the initial manifestation of acute nonlymphocytic leukemia in a young child.

A 15-month-old boy was well except for asymptomatic, erythematous, wheal-like papuloplaques, macules, and nodules on his face and four extremities. It was misdiagnosed by a pediatrician and treated as urticaria for six months. Later, he was sent to our hospital for evaluation of prolonged fever. Acute nonlymphocytic leukemia (M5) with leukemia cutis was diagnosed by results of hematologic examination and examination of a skin biopsy specimen. After one course of chemotherapy, all of the skin lesions completely resolved and had not recurred. Five months after acute nonlymphocytic leukemia was diagnosed, bone marrow relapse and central nervous system involvement were noted.

Humans↗
PubMed1996

Single-stranded DNA binding protein from bacteriophage cf: characterization, gene localization and protein-ssDNA complex.

The single-stranded DNA binding protein from the filamentous bacteriophage cf has been purified and characterized. The first 12 amino acids, resulting from the N-terminal amino acid sequencing analysis of the protein, agree with an open reading frame (ORF) on the cf genome. The ORF contains 294 bp and codes for a 98 a.a. protein of molecular weight 10.8 kDa, consistent with the result from the denaturing protein gel analysis. The protein appears to be a homodimer as evident from the apparent molecular weight of about 22 kDa obtained from native protein gel analysis. The gene location of the protein has been identified as gene V of the cf single stranded genome, same as that from the M13 phage. The GVP of cf shows a strong sequence homology to the ssDNA binding proteins of Ff, IKe and Pf3 filamentous phages. The DNA binding wing of GVP, conserved among the filamentous phages, has been predicted for cf. To further characterize the protein, the GVP-ssDNA complex of cf has been purified from the infected host (Xanthomonas campestris pv. citri) by density gradient centrifugation. Transmission electron microscopy (TEM) images of the complex showed that it is about 1200 nm in length and 9 nm in diameter and it has a highly regular morphology with a central groove shadow running along the entire structure, but without any apparent helical pattern seen in the M13 complex. The GVP-ssDNA complex of cf seems more rigid than that of M13. Our computer modeling study suggested that this difference between the two complexes may be due to the additional 11 or 12 amino acids at the C-terminal end of the cf-GVP.

Amino Acid Sequence↗
PubMed1996

Rifampicin: an inhibitor of Xp12-specific protein phosphorylation in Xanthomonas oryzae pv. oryzae.

Phosphorylation of the three Xp12-specific phosphoproteins was drastically reduced by rifampicin, an antibiotic that specifically inhibits the host-cell RNA polymerase. However, this inhibitory effect could not be found in spontaneous mutants of Xanthomonas oryzae pv. oryzae whose RNA polymerase are resistant to the drug. The inhibitory effect of rifampicin treatment also resulted suppression of the Xp12 multiplication cycle. This implies the physiological significance of this effect and supports our previous prediction that phosphorylation plays an important role in the life cycle of Xp12. The acid- and alkali-labile character of the Xp12-specific phosphoproteins and the chemical stability of the phosphoryl linkages show that the corresponding protein kinase catalyzes the formation of an acyl phosphorylation. Subsequent fractionation of cell lysate revealed that the phosphoproteins were located in the periplasm. Actinomycin D, which affects transcription through DNA condensation rather than its binding to RNA polymerase, was not able to cause the inhibition effect. On the other hand, cerulenin was found to reduce the acyl phosphorylation which hints at a possible role of cell membrane in the phosphorylation. Here we present the evidence for the functional involvement of the rifampicin treatment on protein phosphorylation. A possible mechanism of rifampicin on the alternation of acyl phosphorylation is proposed.

Anti-Bacterial Agents↗
PubMed1996

Acquired generalized hypohidrosis/anhidrosis with subclinical Sjögren's syndrome: report of a case with diffuse syringolymphoid hyperplasia and lymphocytic sialadenitis.

The pathogenesis and the underlying pathologic changes of acquired generalized hypohidrosis/anhidrosis (AGHA) are largely unknown. We studied a case of AGHA in a young woman suffering from heat intolerance and progressive loss of sweating. Pathologic study of affected skin revealed unique syringolymphoid hyperplasia with T cell infiltration, suggesting a T cell-mediated autoimmune disease. The patient also had subclinical Sjögren's syndrome and diffuse hair loss. The pathogenesis of the latter two conditions is believed to be related to the patient's AGHA.

Adult↗