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Biomedical subjects

V T Ho

Publications and source records attributed to V T Ho.

14 recordsLinked to original sources
PubMed2001

Prognostic factors for early severe pulmonary complications after hematopoietic stem cell transplantation.

Pulmonary complications are a significant cause of early mortality (before day 100) after bone marrow transplantation (BMT). To identify factors associated with development of early post-BMT severe pulmonary complications (SPCs), we conducted a retrospective review of the medical records of 339 consecutive patients who underwent hematopoietic stem cell transplantation for hematologic disorders and identified pulmonary complications that occurred before day 60 posttransplantation. SPCs, defined as (1) diagnosis of diffuse alveolar hemorrhage, (2) need for mechanical ventilation, or (3) death from respiratory failure, occurred in 48 (24%) of 199 patients receiving allogeneic transplants and 4 (2.9%) of 140 patients receiving autologous transplants (P < .001). Multiple clinical variables were analyzed to determine their influence on the development of SPCs in allogeneic marrow recipients. The method of graft-versus-host disease (GVHD) prophylaxis was the single most important factor affecting SPC incidence. Of patients who received cyclosporine/methotrexate (CYA/MTX) as GVHD prophylaxis, 33% experienced SPCs compared with 8% of those receiving T-cell depletion (TCD) alone (P < .0001). Multivariate analysis confirmed that TCD was associated with a lower risk of SPCs (relative risk [RR], 0.18; P = .0006). In addition to GVHD prophylaxis, a reduced pretransplantation FEV1 (forced expiratory volume in 1 second) (< or = 80% of predicted) was associated with an increased risk for SPCs (odds ratio, 4.4; P = .0025). Grades 2 to 4 acute GVHD, tobacco use, age > or = 50 years, sex, unrelated donor, cytomegalovirus serologic status, disease status at transplantation, pretransplantation carbon monoxide diffusing capacity, and total body irradiation were not associated with development of SPCs. We conclude that autologous BMT is associated with a significantly lower incidence of SPCs compared with allogeneic BMT and that for allogeneic BMT, GVHD prophylaxis using TCD is associated with a significantly lower risk for SPCs compared with prophylaxis using CYA/MTX. Patients with pretransplantation FEV1 of < or = 80% appear to have a higher risk for SPCs.

Adolescent↗
PubMed1998

Constitutional and mosaic large NF1 gene deletions in neurofibromatosis type 1.

A set of neurofibromatosis type 1 (NF1) patients was screened for large NF1 gene deletions by comparing patient and parent genotypes at 10 intragenic polymorphic loci. Of 67 patient/parent sets (47 new mutation patients and 20 familial cases), five (7.5%) showed loss of heterozygosity (LOH), indicative of NF1 gene deletion. These five patients did not have severe NF1 manifestations, mental retardation, or dysmorphic features, in contrast to previous reports of large NF1 deletions. All five deletions were de novo and occurred on the maternal chromosome. However, two patients showed partial LOH, consistent with somatic mosaicism for the deletion, suggesting that mosaicism may be more frequent in NF1 than previously recognised (and may have bearing on clinical severity). We suggest that large NF1 deletions (1) are not always associated with unusual clinical features, (2) tend to occur more frequently on maternal alleles, and (3) are an important mechanism for constitutional and somatic mutations in NF1 patients.

Adult↗
PubMed1997

Four frameshift mutations in neurofibromatosis type 1 caused by small insertions.

We have been using heteroduplex analysis to assay individual exons within the NF1 gene in an effort to identify disease causing constitutional mutations in neurofibromatosis type 1 patients. Here we report the identification and characterisation of four insertional NF1 frameshift mutations in an analysis of exons 28-39 in a set of 78 patients. These include three 1 base pair insertions and one 2 base pair insertion. Three of these mutations can be attributed to replication slippage errors, while the mechanism behind the fourth may be related to formation of secondary structure during replication. It may be of significance that a majority of the previously reported small insertions in NF1 also lie within exons 28-39.

Adult↗
PubMed1996

Effects of transition metals on the expression of the erythropoietin gene: further evidence that the oxygen sensor is a heme protein.

Both in vivo and in Hep3B cells, expression of the erythropoietin gene is induced by hypoxia as well as by certain transition metals (cobalt and nickel) and by iron chelation. When Hep3B cells were incubated in an iron deficient medium, Epo mRNA expression was enhanced 4-fold compared to Hep3B cells in iron enriched medium. The increased Epo expression in iron deficient medium was abolished when Fe2-transferrin complex was added. Epo induction by cobalt was also affected by iron concentration. In iron enriched medium, erythropoietin expression in Hep3B cells was maximally induced at CoCl2 concentrations between 100 to 200 microM. In contrast, in iron poor medium, a high level of induction was obtained at a CoCl2 concentration of only 50 microM, indicating competition between iron and cobalt. Under hyperbaric oxygen, cobalt induction of erythropoietin mRNA was modestly suppressed while nickel induction was markedly enhanced. These observations support the proposal that the oxygen sensor is a heme protein in which cobalt and nickel can substitute for iron in the porphyrin ring.

Carcinoma, Hepatocellular↗
PubMed1996

Somatic mosaicism in a patient with neurofibromatosis type 1.

Using loss of heterozygosity analysis, a method designed to detect moderate to large gene deletions, we have identified a new-mutation neurofibromatosis type 1 (NF1) patient who is somatically mosaic for a large maternally derived deletion in the NF1 gene region. The deletion extends at least from exon 4 near the 5' end of the gene to intron 39 near the 3' end. The gene-coding region is, therefore, mostly or entirely deleted, encompassing a loss of > or = 100 kb. We hypothesize that the deletion occurred at a relatively early developmental timepoint, since signs of NF1 in this patient are not confined to a specific body region, as seen in "segmental" NF, and since both mesodermally and ectodermally derived cells are affected. This report provides the first molecular evidence of somatic mosaicism in NF1 and, taken together with a recent report of germ-line mosaicism in NF1, adds credence to the concept that mosaicism plays an important role in phenotypic and genetic aspects of NF1 and may even be a relatively common phenomenon.

Adult↗
PubMed1996

CT and MR evaluation of a wooden foreign body in an in vitro model of the orbit.

We made an in vitro model of a wooden foreign body using both fresh and dry pine wood in both fat and soft-tissue background mediums. Air/wood/background medium interfaces were studied with MR and CT to determine which method provided the best image contrast for detecting a wooden foreign body. CT was demonstrated to be superior to MR in the evaluation of the orbit in the in vitro model.

Animals↗
PubMed1996

Intraorbital wooden foreign body: CT and MR appearance.

A case of an intraorbital wooden foreign body mimicking air on standard CT window setting and on MR is presented. Its higher attenuation with higher CT window setting as well as its elongated and well-delineated shape on both CT and MR helped to distinguish it from air.

Child↗
PubMed1994

Postsurgical conjunctival epithelial cysts.

MR appearance of two patients with large, orbital conjunctival epithelium-lined inclusion cysts are presented. Both were complications of ophthalmic surgical procedures that necessitated conjunctival incision.

Adolescent↗
PubMedDate not supplied

CT of adenomas of the middle ear and mastoid cavity.

A case of mixed type adenoma of the middle ear and mastoid is presented in which CT showed complete opacification of the middle ear and mastoid air cells with bulging of the tympanic membrane but without ossicular or bony destruction.

Adenoma↗
PubMedDate not supplied

Unusual subcutaneous sarcoidosis of the face.

Two unusual cases of sarcoidosis manifesting as subcutaneous masses of the face are reported: in the first, the lesion occurred at the site of an osteotomy for rhinoplasty and was the initial clinical manifestation of sarcoidosis; in the second, the skin lesion was part of a multisystemic disease. The cases were documented with CT. Sarcoidosis should be added to the differential of soft-tissue masses of the face.

Adult↗