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Biomedical subjects

G Tung

Publications and source records attributed to G Tung.

12 recordsLinked to original sources
PubMed2001

Minute supernumerary marker chromosomes identified in two patients with a related, larger pseudodicentric chromosome.

We describe two cases in which a minute supernumerary marker chromosome (SMC) was identified in addition to a larger pseudodicentric chromosome. Case 1, a phenotypically normal male, had mosaicism for a psu dic(15;15)(q11.2;q11.2) chromosome and a minute SMC. Fluorescence in situ hybridization (FISH) showed that the minute SMC was D15Z1 positive, indicating a chromosome 15 origin. Case 2 was a 22-week fetus with mosaicism for a normal and two abnormal cell lines: one had a psu dic (22;22)(q11.2;q11.2) chromosome containing euchromatin, usually associated with cat eye syndrome; the other a minute SMC. The minute SMC was positive with the D14Z1/D22Z1 alpha-satellite probe, indicating a chromosome 14 or chromosome 22 origin. Deletion of centromeric material was proposed as one mechanism of centromere inactivation in dicentric chromosomes. The origin of these two minute SMC suggests that they were derived from one of the centromeres of the larger pseudodicentric chromosome. These stable minute SMC may be the by-product of a deletion event inactivating one centromere of a dicentric chromosome to generate a pseudodicentric chromosome. Alternatively, the minute SMC may originate from further rearrangement of the larger pseudodicentric chromosome. These cases suggest possible mechanisms for the origin of minute SMC.

Amniocentesis↗
PubMed1998

Memory processes in depressed geriatric patients with and without subcortical hyperintensities on MRI.

In this study, 12 patients over age 60 with depression with moderate to severe subcortical hyperintensities (SH) localized to the periventricular white matter were identified by quantitative MRI. Using the California Verbal Learning Test, they were compared with 12 age-, education-, and severity-matched patients with depression with minimal white matter changes on specific aspects of memory performance. Patients with cortical lesions, neurologic or systemic illness affecting cognition, and history of substance abuse were excluded. Patients in the group with high SH showed reduced use of semantic encoding strategies (p < 0.05), reduced learning efficiency (p < 0.05), and a greater discrepancy between free recall and recognition discriminability (p < 0.05) than their low SH counterparts. This pattern of performance on memory tasks is similar to that found in previous studies to be associated with subcortical degenerative disorders such as Huntington's and Parkinson's diseases. Geriatric patients with depression with SH may represent a subgroup with greater subcortical involvement, with associated cognitive and functional decline.

Aged↗
PubMed1996

Uptake and localization of lead in corn (Zea mays L.) seedlings, a study by histochemical and electron microscopy.

A detailed microscopic analyses of the mode of lead uptake and localization in root, stem and leaf initials of corn seedlings grown in cultural solution is reported. Lead, as other minerals, was passively absorbed into the root tip region and transported by the active apical growth force. The entrance of lead was mainly from the thin epidermal cell walls at the meristematic region. Only limited amounts of lead entered into protoplasts, primarily during the early stage of cell development. However, accumulation of lead within cell walls increased as cells matured. Both local and long distance transport of lead were apoplastic. Once the vascular stele differentiated from the ground meristem, lead entered into the central conducting systems. Lead was also absorbed from the water absorbing zone but this lead mainly remained in the cortex. The Casparin strip was an effective barrier limiting the movement of lead. However, transport through passage cells was observed. The direction of lead movement was also mainly towards high growth rate areas as seen at meristematic root initials, the leaf primordia and the transaction zone at the stem apical meristem. Damaged plasmalemmae allowed lead to enter cells from cell walls. Lead deposition in the cytoplast was observed.

Absorption↗
PubMed1996

Subcortical hyperintensities on MRI and activities of daily living in geriatric depression.

Data from 30 elderly inpatients with major depression were analyzed to explore the relationship between subcortical hyperintensities (SH) on MRI and activities of daily living (ADLs). A comparison of subjects based on a median split of the severity of SH revealed that subjects with greater SH performed worse on both instrumental and physical ADLs. A hierarchical multiple regression revealed that age, depression severity, neuropsychological test performance, and SH variables accounted for a total of 53% of the variance in ADL functioning. Severity of SH accounted for an additional 18% of the variance over and above the other three variables. Results suggest that severity of subcortical disease measured by MRI improves prediction of functional impairment in elderly individuals.

Activities of Daily Living↗
PubMed1996

MRI and neuropsychological differences in early- and late-life-onset geriatric depression.

We sought to determine whether geriatric patients with late-life-onset major depression have more subcortical hyperintensities on MRI and greater cognitive impairment than age-matched geriatric patients with early-life-onset major depression, suggesting that subcortical disease may be etiologic in late-life depression. Most negative studies of the clinical significance of subcortical hyperintensities on MRI in geriatric patients have sampled from a restricted range of subjects, have employed limited batteries of neuropsychological tests, or have not quantified MRI changes; the present study attempted to address these limitations. Thirty subjects from a geriatric psychiatry inpatient service who were over 60 years of age and presented with major depression were divided into groups with onset of first depression after age 60 (mean = 72.4 years, 15 women, 0 men), and onset of first depression before age 60 (mean = 35.8 years, 12 women, 3 men). Quantitative analysis of MRI yielded the volume of: periventricular hyperintensities (PVH) and deep white-matter hyperintensities (DWMH). Subjects were administered a neuropsychological battery and measures of depression by raters blind to age of onset. The late-onset group had significantly more PVH and DWMH. They were also more impaired on executive and verbal and nonverbal memory tasks. Discriminant analysis using the severity or subcortical signal hyperintensities on MRI, cognitive index, and depression scores correctly predicted late versus early onset of depression in 87% of the early-onset group and 80% of the late-onset group. These findings suggest that late-life-onset depression may be associated with an increased severity of subcortical vascular disease and greater impairment of cognitive performance.

Adult↗
PubMed1989

Drainage of a malignant common hepatic duct obstruction by a biliary endoprosthesis placed through a T-tube tract: technical note.

For patients with high biliary obstruction drained by a T-tube, achieving internal drainage requires special techniques. Modification of a method described by Sammon for common bile duct obstruction permits placement of a biliary endoprosthesis astride the T-tube tract. The key step is traction exerted downward on the endoprosthesis by a suture passing through a second catheter temporarily inserted into the common bile duct. A case is described in which the technique has been applied successfully.

Adenocarcinoma↗
PubMed1989

New universal precaution aspiration tray.

A new tray has been designed for use during procedures involving needles and other sharp objects. The tray includes a foam adhesive pad, marked into 10 sections, into which the sharp objects can be placed point first. After the procedure, the objects can be safely withdrawn by their handles and then discarded. The tray has been used in more than 250 procedures.

Accident Prevention↗
PubMed1989

The sonographic diagnosis of acute gangrenous cholecystitis: importance of the Murphy sign.

The sonographic Murphy sign is defined as the presence of maximal tenderness elicited by direct pressure of the transducer over a sonographically localized gallbladder. The reported prevalence of this sign is more than 95% in patients with acute cholecystitis. In this series of 18 patients with pathologically proved gangrenous cholecystitis, the sonographic Murphy sign was positive in only six (33%). Clinical examination showed a positive Murphy sign in eight patients (44%), diffuse abdominal pain in nine patients (50%), and no pain in one patient (6%). Other sonographic findings included pericholecystic fluid (10), thickening of the gallbladder wall (10), and a dilated gallbladder (five). Our experience suggests that the absence of the Murphy sign increases the possibility of gangrenous cholecystitis in patients with abdominal pain and sonographic findings of cholecystitis.

Abdomen↗
PubMed1984

Second nonocular tumors in retinoblastoma survivors. Are they radiation-induced?

A review of 693 patients with bilateral retinoblastoma and 18 patients with unilateral/germinal retinoblastoma was carried out to find the incidence, time, course and pattern of second nonocular tumors in retinoblastoma survivors. Of 688 patients who survived therapeutic radiation for retinoblastoma, 89 developed second tumors: 62 in the field of radiation and 27 out of the field. Of 23 patients who received no radiation, five developed second tumors: one in the field and four out of the field. The most common tumor found was a sarcoma both in and out of the field of radiation. The incidence of second tumors increases with time, although the mean latent period is 10.4 years. At 10 years, the incidence of second tumors is 20%, at 20 years, it is 50% and at 30 years, 90%. The incidence of tumors in patients treated without radiation and where tumors developed outside the field was 10% at 10 years, 30% at 20 years and 68% at 32 years. There was no relationship between incidence of tumors and dose of therapeutic radiation when analyzed with life tables. A second course of radiation therapy did not increase the incidence of second nonocular tumors.

Brain Neoplasms↗