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Biomedical subjects

C Wong

Publications and source records attributed to C Wong.

At least 271 records · Page 15Linked to original sources

Anti-inflammatory effect of glutathione peroxidase on experimental lens-induced uveitis.

An acute lens-induced necrotizing intraocular inflammation was produced in Lewis rats. Treatment of these animals by intraperitoneal injection of glutathione peroxidase resulted in marked decrease in uveal inflammation, retinal edema, hemorrhage and vasculitis. Intraperitoneal injection of glutathione peroxidase resulted in increased levels of this enzyme in ocular tissue. These findings suggest that glutathione peroxidase can modulate acute lens-induced ocular inflammation by serving as a potent anti-inflammatory agent.

Animals↗

Beta-thalassemia in China: a systematic molecular characterization of beta-thalassemia mutations.

In order to initiate a program of prenatal diagnosis for the prevention of beta-thalassemia in China, we have begun systematic studies of the beta-thalassemia mutations among the Chinese. DNA polymorphisms in the beta-globin gene cluster were examined in 46 beta-thalassemia chromosomes. Six different haplotypes were observed. One beta-thalassemia gene associated with a new haplotype was cloned and sequenced. The mutation was a single base substitution (A----G) at position -29 within the highly conserved proximal promoter element (the "TATA" box). This mutation was not observed previously in the Chinese. The beta-thalassemia genes were further screened with oligonucleotide probes specific for all known mutations in the Chinese. Five mutations were identified and accounted for 35 beta-thalassemia alleles.

Child↗

Moderately severe hemophilia A resulting from Glu----Gly substitution in exon 7 of the factor VIII gene.

To define the molecular basis of a TaqI site alteration in the factor VIII gene of a patient with moderately severe hemophilia A, we used a combination of genomic amplification followed by direct sequencing and oligonucleotide hybridization, to demonstrate an A-to-G substitution in exon 7 (codon 291) of this gene. This mutation generates a Gly in place of Glu at amino acid 272 of the mature factor VIII protein. The mutation arose de novo in a germ cell of the patient's mother.

Adolescent↗

Determination of the spectrum of beta-thalassemia genes in Spain by use of dot-blot analysis of amplified beta-globin DNA.

We have delineated the molecular lesions causing beta-thalassemia in Spain, a country that has witnessed the passage of different Mediterranean populations over the centuries, in order to evaluate the extent of heterogeneity of these mutations and to make possible simplified prenatal diagnosis of the disorder in that country. The use of the polymerase chain-reaction (PCR) technique to preferentially amplify beta-globin DNA sequences that contain the most frequent beta-thalassemia mutations in Mediterraneans enabled us to rapidly analyze 58 beta-thalassemia alleles in a dot-blot format either by hybridization with allele-specific radiolabeled oligonucleotide probes or by direct sequence analysis of the amplification product. The Spanish population carries seven different beta-thalassemia mutations; the nonsense codon 39 is predominant (64%), whereas the IVS1 position 110 mutation, the most common cause of beta-thalassemia in the eastern part of the Mediterranean basin, is underrepresented (8.5%). The IVS1 mutation at position 6 accounts for 15% of the defects and leads to a more severe form of beta+-thalassemia than originally described in most of the patients we studied. In this study, we demonstrate further the usefulness of the dot-blot hybridization of PCR-amplified genomic DNA in both rapid population surveys and prenatal diagnosis of beta-thalassemia.

Base Sequence↗

Nursing staff response to a facility's relocation.

RESPONSE RATE--approximately 200 questionnaires were distributed and 101 were returned and collated. The response rate was 51 percent. ORIENTATION--the results were as follows: 89 percent of staff surveyed attended orientation; many staff took more than one tour (55.6 percent had two or more), which may be an important factor in adjustment; 75.2 percent indicated tht orientation was relevant, and those who did not recommended more specific unit orientation; and 31 percent said there was too much information and perhaps this should be examined in future orientation programs. OMISSIONS--many commented that specific, hands-on orientation to the equipment such as telephones and the call system would have been beneficial, as well as orientation to their own specific unit. Smaller orientation groups would also seem to be warranted in light of this information. COMMUNICATION CONCERNING THE MOVE--approximately 79 percent of the staff attended at least one staff meeting prior to the move, and 78 percent knew of the moving schedule. However, subsequent (and frequent) changes in this schedule were mentioned as a source of frustration. About 13 percent indicated a need for more staff input into the move and would suggest more open forums or discussion groups to solicit input as a way of increasing staff participation and commitment to the move. A need for frequent, reliable written communication was mentioned frequently as misinformation or word-of-mouth information led to unnecessary frustrations. It is interesting to note that approximately 80 percent of respondents had no suggestions to improve communication, and it is difficult to know whether this may indicate satisfaction with communication mechanisms or a lack of ideas on how to improve the situation. SENSE OF PREPAREDNESS FOR THE MOVE--80.4 percent gave a high rating to indicate how prepared they felt regarding the move, which is really very positive. PROBLEMS ADJUSTING TO NEW ENVIRONMENT--most of the responses (48%) related to problems with communication systems, particularly the phone system, problems with the phone listing book and lack of directional signs. Suggestions for facilitating adjustment closely followed the above responses in that more and better signs, and more effective means for directing staff, patients and visitors, were frequently cited. CURRENT FRUSTRATIONS--respondents were asked to detail ongoing and current frustrations. Environmental concerns such as excessively dry air and the cleanliness of the building were noted and earmarked for further investigation. It is worthy of note that concerns relating to nurse staffing were mentioned very infrequently both during and after the move.

Anxiety↗

[Nuclear magnetic resonance imaging in gynecology. An evaluation of its current applications].

The authors present a research carried out by the Universities of Essen, Tubingen (RFA) and Grenoble, France, on the use of magnetic resonance imaging (M.R.I.) in gynaecology. After clarifying our knowledge of the normal anatomy of the pelvis and of the tissular characteristics of MRI the principal indications are discussed and set out. The investigation is shown to be particularly valuable in working out the aetiology, the volume and the spread of a pelvic mass whether it is benign or malignant when it is important to be exact in finding the origin of the tumour. This research has been illustrated by analysing 35 case histories including 28 malignant tumours. A second study was carried out on 30 cases of cancer of the cervix. In this field MRI is the only test that can be carried out before therapy to give a tridimensional assessment of the size of the tumour and whether it has spread into the parametrium. The visual impressions obtained by MRI illustrate each chapter: of the gynaecological anatomy, of the pathology, in cancers of the cervix, in pelvic masses and particularly in ovarian tumours.

Female↗

Electron microscopy and biochemical properties of polyamine-compacted DNA.

We have obtained polyamine-compacted DNA and analyzed it by electron microscopy employing the method described by Dubochet, suitable for the study of complexes in which the main interactions are of ionic character. In addition, we have developed a simple biochemical method, based on the action of pancreatic DNase I, to demonstrate the condensation of DNA with spermidine. DNA-spermidine complexes are resistant to the action of DNase I, and there is a strong correlation between the presence of condensed DNA forms, both as toroids and as cylinders, and the insensitivity to DNase I activity. We have also shown that pBR322 DNA-spermidine complexes are transcriptionally active in the presence of Escherichia coli RNA polymerase. This supports the data concerning the biological activity of spermidine-condensed DNA.

DNA↗

Evidence for reduced recombination on the nondisjoined chromosomes 21 in Down syndrome.

Trisomy 21 usually results from nondisjunction during meiosis I. In order to determine whether nondisjunction results from failure of normal chromosome pairing or premature unpairing, recombination frequencies were estimated between DNA polymorphic markers on the long arm of chromosome 21 in families containing one individual with trisomy 21. The recombination frequencies on chromosomes 21 that had undergone nondisjunction were then compared to those on chromosomes 21 that had disjoined normally. The data indicate that recombination is reduced between DNA markers on nondisjoined chromosomes 21. These results are consistent with the hypothesis that reduced chiasma formation predisposes to nondisjunction, resulting in trisomy 21 in humans.

Chromosome Mapping↗

Liposomes with polyribonucleotides as model of precellular systems.

A study of the encapsulation of poly(U) and poly(C) within liposomes made from dipalmitoylphosphatidyl choline (DPPC), from egg yolk phosphatidyl choline (PC), and from PC with cholesterol (CHOL) was made. The liposomes were prepared under anoxic conditions following the reverse-phase evaporation method. Determinations showed that 36 to 70% of the available lipids form liposomes and 2 to 5% of the polyribonucleotides can be entrapped by liposomes. The encapsulation of polyribonucleotides has also been measured in the presence of urea, cyanamide and Zn++, condensing agents in prebiotic polymerization reactions. DPPC and PC:CHOL liposomes were formed in the presence of 1.0 M urea, although no PC liposomes were formed. The three types of liposomes were readily formed at 0.01 M urea, but in no case an enhancement of encapsulation efficiency of poly(U) was observed due to the presence of urea. Similar results were obtained with cyanamide. An enhanced encapsulation of poly(U) by the three types of liposomes was observed when Zn++ was in the range of 0.001 to 0.01 M. Poly(U) encapsulation was 15 to 25 times higher when liposomes were prepared from DPPC at 0.01 M Zn++. Similar results were obtained with poly(C). The advantages of DPPC-polyribonucleotide liposomes as precellular systems are discussed.

1,2-Dipalmitoylphosphatidylcholine↗

Tumorigenesis in transgenic mice by a nuclear transport-defective SV40 large T-antigen gene.

The SV40(cT) mutant encodes a large tumor antigen (cT-ag) that is defective for transport from the cell cytoplasm into the nucleus. This mutant is able to transform established cell lines at near wild-type virus efficiencies, but has a markedly decreased ability to transform primary cells and to induce tumors in newborn hamsters (R. E. Lanford, C. Wong, and J. S. Butel, 1985, Mol. Cell. Biol. 5, 1043-1050). To explore the biology of transport-defective T-ag in vivo, transgenic mice carrying the cT-ag gene were produced. Five of eight founder animals died early in life of choroid plexus tumors (mean age +/- SE, 52 +/- 11.0 days); renal and thymic lesions were also observed. Mice of an SV40(cT) transgenic line regularly succumb to brain tumors (mean age, 81 +/- 1.2 days). SV40 T-ag is expressed in the tumor cells and is retained in the cytoplasm. The observation that SV40(cT) is equivalent to wild-type virus at tumor induction in transgenic mice emphasizes the probable importance of extranuclear forms of SV40 T-ag in brain tumor formation. This study also indicates that in vitro cell transformation assays may not always be accurate reflections of the oncogenic potential of a transforming gene in vivo, because of the different cell types involved.

Animals↗

Immunoreactive prolyl hydroxylase in patients with primary and secondary myelofibrosis.

Prolyl hydroxylase (PH) is an important enzyme in collagen synthesis. It is required for the hydroxylation of prolyl residues in peptide chains in collagen synthesis. Serum PH activity was measured in patients with primary myelofibrosis (agnogenic myeloid metaplasia and myelofibrosis with prior history of polycythaemia vera), in patients with secondary myelofibrosis (in association with carcinoma metastasis), in patients with other myeloproliferative disorders and in controls (anaemia patients and normal volunteers). Both primary and secondary myelofibrosis had significantly elevated PH values, while other myeloproliferative disorders did not differ from normal controls. Increased PH levels in patients with primary and secondary myelofibrosis may signify increased collagen synthesis and may serve as an indicator for the development of fibrosis in the course of myeloproliferative disease.

Aged↗

Pre-treatment with beta blockers and the frequency of hypokalaemia in patients with acute chest pain.

Plasma potassium concentration was measured at admission in 1234 patients who presented with acute chest pain. One hundred and ninety five patients were on beta blockers before admission. The potassium concentrations of patients admitted early (within four hours of onset of symptoms) were compared with those admitted later (4-18 hours after onset of symptoms). There was a transient fall in plasma potassium concentrations in patients not pre-treated with beta blockers. This was not seen in patients who had been on beta blockers before admission. Non-selective beta blockers were more effective than cardioselective agents in maintaining concentrations of plasma potassium. These findings suggest a mechanism for the beneficial effects of beta blockers on morbidity and mortality in acute myocardial infarction.

Adrenergic beta-Antagonists↗

A new mutation in IVS-1 of the human beta globin gene causing beta thalassemia due to abnormal splicing.

A G to T transversion at the fifth nucleotide of the first intervening sequence (IVS-1) of the beta-globin gene has been identified in cloned beta-thalassemia genes of two unrelated individuals, one of Mediterranean and the other of Anglo Saxon ancestry. In each patient the mutation was present in a different beta globin gene framework, defined by intragenic restriction site polymorphisms, thereby suggesting the occurrence of independent mutations. The study of the RNA products of one of these cloned genes, after transfer and transient expression in HeLa cells, showed partial inactivation of the normal donor splice site of IVS-1 and activation of two major and one minor cryptic splice sites. Only one of the two major cryptic sites was utilized in a cell-free splicing extract. The effects of this mutation on messenger RNA (mRNA) splicing are similar to that of another beta thalassemia gene with a G to C transition at the same position.

Base Sequence↗

[A new case of cyst of the common bile duct with an anomaly of the bilio-pancreatic convergence].

A case of common bile duct cyst operated upon in a 2 1/2 year old girl is used as a basic for discussing the forms associated with anomaly of convergence of common bile and wirsung's ducts. The latter, of dysembryoplastic origin, appears to be the cause of this type of cyst. These forms are atypical in that no mass is palpable and they are frequently complicated by a pancreatitis. They constitute the majority of Japanese cases when the anomaly is investigated. Its detection is possible by retrograde catheterization or more rarely during perioperative cholangiography, the only possibility in the very young infant. Different operative technics are outlined, taking into account principally the risk of secondary malignant changes and the possible performance of a hepatico-duodenal anastomosis without increasing the risk of an ascending angiocholitis.

Child, Preschool↗

The painful swollen calf. A comparative evaluation of four investigative techniques.

Complications of popliteal cysts may closely mimic the clinical features of a deep venous thrombosis. We assessed the sensitivity and specificity of the non-invasive procedures of radionuclide venography and popliteal space ultrasound examination compared with those of contrast venography and arthrography, respectively, and then prospectively studied 23 non-surgical patients with acutely painful, swollen calves to determine the utility of these techniques. The cause of this symptom was popliteal cyst complications in 10 patients, deep venous thrombosis in seven patients, and both conditions in two patients. Radionuclide venography was highly reliable and ultrasound examination was specific but only moderately sensitive in these studies. The painful, swollen calf may be investigated adequately in most cases by means of noninvasive invasive techniques; contrast venography and arthrography should be reserved for only a minority of patients.

Adult↗

The same "TATA" box beta-thalassemia mutation in Chinese and US blacks: another example of independent origins of mutation.

A Chinese beta +-thalassemia gene in a new haplotype was chosen for cloning and sequencing. The mutation identified was an A-G transition at position -29 in the TATA box of the beta-globin gene. This mutation has not been seen previously in Chinese but has been documented in American blacks on a different chromosomal background. This observation provides further evidence for independent origins of the same mutation in distinct ethnic groups.

Asian People↗

Uterine arginase inhibition affect the rat embryonic development.

The presence of polyamines (putrescine, spermidine and spermine) and the enzymatic activity of extrahepatic arginase (E.C. 3.5.3.1) which catalizes the hydrolysis of L-arginine into L-ornithine and urea have been related with cellular growth and development in several tissues. The enzymatic activity of arginase in rat implantation sites and its participation in reproductive process is demonstrated. Long-Evans adult rats during the 4th or 5th days of pregnancy were utilized. Arginase activity is higher in non-decidualized tissue (86.1 +/- 33 nmoles of urea/mg protein/min-1) when was compared with implantation sites (61.7 +/- 17). Intrauterine administration of several concentrations of a new synthetic L-ornithine analogue, AIAVA (2-amine-5-iodoacetamide valeric acid), produced embryonic growth arrest concomitant with arginase inhibition but not ornithine decarboxylase. From our results it is possible to stress the metabolic importance of uterine arginase in reproductive process.

Animals↗