Managed care, managing uncertainty.
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Health Resources↗
Biomedical subjects
C F Chang
Publications and source records attributed to C F Chang.
Evidence for regulation of transcription and replication of the human neurotropic virus JCV genome by the human S(mu)bp-2 protein in glial cells.
Glial factor 1 (GF-1) is a partial cDNA isolated from a human brain cDNA library which encodes a truncated protein with binding ability to the B-regulatory domain of the human neurotropic virus, JCV. GF-1 exhibits sequence homology to the central region of the newly identified human DNA-binding protein S(mu)bp-2. GF-1 appears to be a partial cDNA for human S(mu)bp-2 based on its sequence homology to S(mu)bp-2 and their chromosomal co-localization. In this report, we have employed transfection assay and have compared the ability of GF-1 and its full-length form, S(mu)bp-2, on regulating the activity of JCV promoters in glial cells. Our results demonstrate that, unlike GF-1 which stimulates JCV early promoter in glial cells, overexpression of S(mu)bp-2 exhibits no drastic effect on the transcription of the viral early promoter. The activity of the viral late promoter was noticeably increased by both GF-1 and S(mu)bp-2, although the level of induction by GF-1 was consistently higher than that detected by S(mu)bp-2. Use of deletion constructs in co-transfection assay revealed that the B-domain of the JCV promoter is required for transcriptional activation by GF-1 and S(mu)bp-2. Expression of GF-1 and S(mu)bp-2 in glial cells increased the induced level of JCV late gene transcription by the viral early protein, T-antigen. Examination of the viral DNA replication by DpnI assay indicated that, unlike GF-1, S(mu)bp-2 has the ability to decrease the level of JCV DNA replication in glial cells. These observations suggest that the N-terminal portion of S(mu)bp-2 which encompasses several helicase motifs and/or its C-terminus, both of which are missing in GF-1, may confer differential effects on viral gene transcription and replication. The biological importance of our findings in regulation of the JCV lytic cycle in glial cells is discussed.
Antigens, Viral, Tumor↗
Protecting older people while managing their care.
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Advance Care Planning↗
Identification of a locus involved in the utilization of iron by Actinobacillus pleuropneumoniae.
The cloned afu locus of Actinobacillus pleuropneumoniae restored the ability of an Escherichia coli K-12 mutant (aroB) to grow on iron-limited media. DNA sequence analysis of the fragment showed that there are three genes designated afuA, afuB and afuC (Actinobacillus ferric uptake) that encode products similar to the SfuABC proteins of Serratia marcescens, the HitABC proteins of Haemophilus influenzae, the FbpABC proteins of Neisseria gonorrhoeae and the YfuABC proteins of Yersinia enterocolitica. The three genes encode a periplasmic iron-binding protein (AfuA), a highly hydrophobic integral cytoplasmic membrane protein with two consensus permease motifs (AfuB) and one hydrophilic peripheral cytoplasmic membrane protein with Walker ATP-binding motifs (AfuC), respectively. This system has been shown to constitute a periplasmic binding protein-dependent iron transport system in these organisms. The afuABC operon is locating approximately 200 bp upstream of apxIC gene, but transcribed in opposite direction to the ApxI-toxin genes.
Actinobacillus pleuropneumoniae↗
Evidence that the soluble factors secreted by activated immune cells suppress replication of human neurotropic JC virus DNA in glial cells.
Coordination of the immune response to viral infection and disease in the brain is believed to involve bidirectional interaction between the immune system and the central nervous system (CNS). Progressive multifocal leukoencephalopathy (PML) is a demyelinating disease of the CNS that generally affects patients exhibiting an immunocompromised condition due to various illnesses. The human polyomavirus, JCV, which infects greater than 70% of the adult population is the etiological agent of this disease. Infection with JCV occurs during childhood and the virus remains in the latent state with no apparent clinical signals. However, under immunocompromised conditions, the virus enters the lytic cycle, and upon cytolytic destruction of glial cells, causes PML. To understand the molecular mechanism underlying immune regulation of JCV replication, we have developed a cell culture system and have investigated the effect of soluble factors from T-cell cultures on replication of JCV DNA in glial cells. Our data demonstrate that replication of JCV DNA in the presence of PMA-stimulated T-cell supernatant is substantially decreased in transfected glial cells. Heat-inactivation and size-fractionation studies revealed participation of a heat labile factor(s) which loses its maximum activity at 60 degrees and ranges between 30 and 100 kDa in size. The unfractionated T-cell supernatant and the fraction enriched in 30- to 100-kDa proteins reduced the level of viral DNA replication during the early phase of the lytic cycle. These observations suggest that regulatory factors which are secreted by immune cells may modulate the level of JCV DNA replication in glial cells. The importance of these observations in reactivation of JCV in immunocompromised individuals and development of PML is discussed.
Antigens, Polyomavirus Transforming↗
Establishment and characterization of a human-papillomavirus negative, p53-mutation negative human cervical cancer cell line.
A human cervical cancer cell line, CX, was established from a patient with squamous cell carcinoma of the uterine cervix. The CX cells were epithelial in morphology with relatively large vesicular nuclei, and prominent nucleoli. Cytoplasmic organelles were generally sparse but tonofilaments were relatively abundant. The cells grew as a compact sheet with close membrane approximation interconnected by desmosome-like junctions. CX cells contained cytokeratin, but not vimentin. Elevated levels of squamous cell carcinoma antigen and carcinoembryonic antigen were detected in the cell supernatants. Population doubling time was estimated to be about 20 h. CX cells were not able to grow in soft agar and not tumorigenic in nude mice. Chromosome analysis revealed that CX cells were heterogeneous and mainly had a female diploid karyotype. Unlike cervical cancer cell lines published previously, CX cells were demonstrated to be human papillomavirus-negative, p53 mutation-negative. Based on the distinct characteristics, CX cell line may prove to be a useful tool for the study of human cervical carcinogenesis.
Antigens, Neoplasm↗
Altered structural and mechanistic properties of mutant dihydropteridine reductases.
Nine single genetic mutants of rat dihydropteridine reductase (EC 1.6.99.7), D37I, W86I, Y146F, Y146H, K150Q, K150I, K150M, N186A, and A133S and one double mutant, Y146F/K150Q, have been engineered, overexpressed in Escherichia coli and their proteins purified. Of these, five, W86I, Y146F, Y146H, Y146F/K150Q, and A133S, have been crystallized and structurally characterized. Kinetic constants for each of the mutant enzyme forms, except N186A, which was too unstable to isolate in a homogeneous form, have been derived and in the five instances where structures are available the altered activities have been interpreted by correlation with these structures. It is readily apparent that specific interactions of the apoenzyme with the cofactor, NADH, are vital to the integrity of the total protein tertiary structure and that the generation of the active site requires bound cofactor in addition to a suitably placed W86. Thus when the three major centers for hydrogen bonding to the cofactor are mutated, i.e. 37, 150, and 186, an unstable partially active enzyme is formed. It is also apparent that tyrosine 146 is vital to the activity of the enzyme, as the Y146F mutant is almost inactive having only 1.1% of wild-type activity. However, when an additional mutation, K150Q, is made, the rearrangement of water molecules in the vicinity of Lys150 is accompanied by the recovery of 50% of the wild-type activity. It is suggested that the involvement of a water molecule compensates for the loss of the tyrosyl hydroxyl group. The difference between tyrosine and histidine groups at 146 is seen in the comparably unfavorable geometry of hydrogen bonds exhibited by the latter to the substrate, reducing the activity to 15% of the wild type. The mutant A133S shows little alteration in activity; however, its hydroxyl substituent contributes to the active site by providing a possible additional proton sink. This is of little value to dihydropteridine reductase but may be significant in the sequentially analogous short chain dehydrogenases/reductases, where a serine is the amino acid of choice for this position.
Amino Acid Sequence↗
The effect of N-methylation on helical peptides.
In N-methyl amino acids, the hydrogen of the N-H group is replaced with a bulky methyl group. While this change is expected to destabilize helical structures, the amount of destabilization is not known. Here the N-methyl group is placed into several positions of the helical peptides, acetyl-WGG(EAAAR)4A-amide and acetyl-WGG(RAAAA)4R-amide, and the melting of the peptides followed using CD. When analyzed using a simple two-state model, the destabilization associated with the H to CH3 substitution at 0 degree C is between 0.3 to 1.7 kcal/mole and is position dependent. The melting data may also be analyzed using a modified form of the Lifson-Roig statistics that should more correctly model the helix-coil transition in this small peptide. This analysis fails, however, apparently because the destabilization energy is greater than the energy that can be attributed to a single residue in this model.
Amino Acid Sequence↗
Factors influencing tumor cell kinetics in cervical cancer.
Fresh tumor tissues instead of paraffin-embedded sections were used to study the clinical significance of the tumor cell kinetics in cervical carcinomas by flow cytometry. We analyzed specimens from 153 women with cervical cancer, and DNA aneuploidy was found in 61 cases (39.9%). The mean age of patients with aneuploid tumors was significantly higher than the age of patients with diploid tumors (P < 0.001). The mean proliferation index for aneuploid tumors was significantly higher than those for diploid tumors. There was a significant correlation between the proliferation index and age. However, tumor cell kinetics is not related to the status of human papillomavirus, herpes simplex virsuses I and II, lymph nodes, histology or tumor size. The mean age and S-phase fraction for stage-II tumors were significantly higher than those for stage-I tumors (P < 0.01). The tumors of menopausal patients exhibited a relatively higher rate of lymph node metastasis, and significantly higher aneuploidy rate and proliferation index than tumors of premenopausal patients. In summary, age and, what is more important, menopausal status may significantly influence DNA ploidy and cell kinetics of tumors, and subsequently influence clinical stage and lymph node metastasis. However, tumor cell kinetics is of limited value in the prediction of lymph node metastasis and prognosis.
Adult↗
When to discharge patients with bleeding peptic ulcers: a prospective study of residual risk of rebleeding.
BACKGROUND: From January 1993 to December 1994, we conducted a prospective study to investigate the evolutionary change of rebleeding risk in bleeding peptic ulcers. To obviate possible confounding factors that would influence decision making for discharge of patients, subjects with coexistent acute illnesses, systemic bleeding disorders, alcoholism, and use of nonsteroidal anti-inflammatory drugs were excluded. METHODS: Emergency endoscopies were performed in patients with hematemesis or a melena within 24 hours of admission. Ulcer lesions were divided into six categories according to endoscopic findings. The residual risks of rebleeding of each type of ulcers were calculated for 10 days, and the critical point of acceptable rebleeding risk after discharge was set at 3%. RESULTS: Three hundred ninety-two patients with bleeding peptic ulcers completed the study. The ulcers, characterized by clean bases, red or black spots, adherent clots, nonbleeding visible vessels without local therapy, nonbleeding visible vessels with local therapy, and bleeding visible vessels with local therapy took 0, 3, 3, 4, 4, and 3 days, respectively, to decrease rebleeding risk to below the critical point. All episodes of fatal rebleeding (n = 4) occurred within 24 hours after admission. CONCLUSIONS: Patients with clean-based ulcers can be discharged in the first day of admission. The optimal duration required for hospitalization of patients with ulcers characterized by nonbleeding visible vessels at initial endoscopy is 4 days. The remaining patients with ulcers marked by other bleeding stigmata may be discharged after a 3-day observation.
Adolescent↗
The impact of endoscopic variceal ligation on the pressure of the portal venous system.
BACKGROUND/AIMS: Endoscopic variceal ligation is a viable substitute for injection sclerotherapy. It is still not known how endoscopic variceal ligation may influence the portal venous system. To clarify this issue we investigated the impact of endoscopic variceal ligation on the pressure of the portal venous system. METHODS: Twenty-nine patients with a history of esophageal variceal bleeding but without ascites were enrolled. All had cirrhosis; 63% of them were post-hepatitic. Ligation was performed at intervals of 2-3 weeks until all the varices were obliterated. Portal venograms were performed before institution of ligation and after variceal obliteration to assess venographic findings and pressure changes. The pressures of the main portal vein, splenic vein and superior mesenteric vein were recorded. RESULTS: Twenty-five patients completed the study. A mean of 4.4 sessions (range: 2-7) of ligation over a period of 2 months was needed. Seventeen (68%) patients experienced elevated pressure and eight (32%) patients reduced pressure after ligation. Mean (median) pressure changes were as follows: portal venous pressure, 26.5 +/- 4.7 (25.0) mmHg vs. 28.2 +/- 7.2 (28.0) mmHg (p > 0.05); splenic venous pressure, 28.2 +/- 4.9 (26.0) mmHg vs. 29.0 +/- 6.8 (29.0) mmHg (p > 0.05); superior mesenteric venous pressure, 28.4 +/- 6.0 (27.0) mmHg vs. 29.5 +/- 7.0 (29.0) mmHg (p > 0.05). Five patients (20%) experienced rebleeding before variceal obliteration; all of them presented elevated portal pressures after variceal obliteration. Among the eight patients with decreased portal pressure, seven (87%) had other major collaterals apart from esophageal varices, compared to three out of the 17 (18%) patients with elevated portal pressure who had other major collaterals (p < 0.01). CONCLUSIONS: Among patients receiving endoscopic variceal ligation, 68% experienced elevated portal pressure, while 32% had decreased portal pressure. Elevation of portal pressure after variceal ligation may be an important factor in variceal rebleeding. The presence of other major collaterals apart from esophageal varices may be responsible for the decrease in portal pressure after obliteration of esophagel varices.
Adult↗
Evidence that replication of human neurotropic JC virus DNA in glial cells is regulated by the sequence-specific single-stranded DNA-binding protein Pur alpha.
Initiation of polyomavirus DNA replication in eukaryotic cells requires the participation of the viral early protein T antigen, cellular replication factors, and DNA polymerases. The human polyomavirus JC virus (JCV) is the etiologic agent of the fatal demyelinating disease progressive multifocal leukoencephalopathy in immunocompromised individuals. This virus exhibits a narrow host range and a tissue specificity that restricts its replication to glial cells of the central nervous system. Restriction of viral DNA replication due to species specificity of the DNA polymerase, coupled with glial cell-specific transcription of the viral early promoter, is thought to account for the brain-specific replication of JCV. In this report we demonstrate that overexpression of Pur alpha, a protein which binds to single-stranded DNA in a sequence-specific manner, suppresses replication of JCV DNA in glial cells. Results from footprinting studies indicate that Pur alpha and T antigen share a common binding region spanning the single-stranded ori sequence of JCV. Further, T antigen was capable of stimulating the association of Pur alpha with the ori sequence in a band shift assay. Whereas no evidence for simultaneous binding of Pur alpha and T antigen to single-stranded DNA has been observed, results from coimmunoprecipitation and Western blot (immunoblot) analyses of proteins derived from cells producing JCV T antigen indicate a molecular association of JCV T antigen and Pur alpha. The binding of Pur alpha to the single-stranded ori sequence and its association with T antigen suggest that Pur alpha interferes with the activity of T antigen and/or other regulatory proteins to exert its negative effect on JCV DNA replication. The importance of these findings in the reactivation of JCV in the latently infected individual under immunosuppressed conditions is discussed.
Antigens, Viral↗
Gallbladder function and recurrent stones of the biliary tract in patients after endoscopic sphincterotomy.
BACKGROUND: Change in gallbladder function may occur in patients with an intact gallbladder after endoscopic sphincterotomy (EST). This study was designed to evaluate the factors influencing gallbladder filling after EST and the correlation between gallbladder function and stone recurrence. METHODS: Sixty Chinese patients with symptomatic choledocholithiasis and an intact gallbladder received EST to clear the bile ducts. They were further investigated with sphincter of Oddi manometry (SOM), quantitative cholescintigraphy (QC), and long-term clinical follow-up. RESULTS: Fifty-six of the 60 patients in the study group were confirmed to have a loss of sphincteric function by SOM. QC showed normal gallbladder filling in 35 of these patients and delayed or non-filling in 21 patients. A significantly higher incidence of normal gallbladder filling occurred in patients with juxtapapillary diverticulum than in those without (P < 0.02), but preexisting cholecystolithiasis had no effect on it. During the follow-up period (median, 32 months: range, 9-54 months) 10 of 56 patients developed recurrent choledocholithiasis. There was no correlation between the status of gallbladder filling, preexisting cholecystolithiasis, and recurrent stones, but 9 of the 10 patients with recurrent stones had a juxtapapillary diverticulum. Repeated endoscopic treatment was satisfactory in eight patients, and only two patients received cholecystectomy. CONCLUSIONS: EST does not alter gallbladder function in most patients. Juxtapapillary diverticulum may facilitate gallbladder filling after EST, but it is also a possible factor for recurrent choledocholithiasis.
Aged↗
Grading TennCare.
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Health Maintenance Organizations↗
The efficacy of endoscopic sphincterotomy in patients with sphincter of Oddi dysfunction.
BACKGROUND: Dysfunction of the sphincter of Oddi (SOD) is one of the causes of postcholecystectomy syndrome and biliary pain. Endoscopic sphincterotomy (EST) is recommended in some patients refractory to conservative treatment. This study was designed to evaluate the efficacy of, and complications from EST in patients with SOD. METHODS: Between 1990 and 1993, 24 patients clinically diagnosed as having papillary stenosis were treated by endoscopic sphincterotomy. All patients had dilated common bile duct (CBD) in addition to 1) elevation of transaminases and alkaline phosphatase (n = 13); 2) elevation of transaminases and serum amylase (n = 4); 3) normal liver enzymes but delayed biliary emptying on quantitative hepatobiliary scintigraphy (QHS) (n = 7). No CBD stones, organic obstruction or other disorders were found in these patients. RESULTS: EST was successfully performed in 24 patients. One patient had minor hemorrhage and one patient developed pancreatitis after EST. Twenty-two of the 24 patients (91.7%) were symptomatically improved before discharge. Twenty-one patients were regularly followed over a median period of 18 months (range 5-36) after EST. Two patients with symptom had recurrence at five and eight month follow up because of restenosis of papilla; another two patients with recurrent biliary symptoms, but the sphincter of Oddi remained wide open. Seventeen of 21 regularly followed patients were symptom free after the median 18-month follow up. CONCLUSIONS: EST is an effective and safe modality for treatment of sphincter of Oddi dysfunction.
Adult↗
Roles of a membrane-localized beta subunit in the formation and targeting of functional L-type Ca2+ channels.
We report several unexpected findings that provide novel insights into the properties and interactions of the alpha 1 and beta subunits of dihydropyridine-sensitive L-type channels. First, the beta 2a subunit was expressed as multiple species of 68-72 kDa; the 70-72-kDa species arose from post-translational modification. Second, cell fractionation and immunocytochemical studies indicated that the hydrophilic beta 2a subunit, when expressed alone, was membrane-localized. Third, the beta 2a subunit increased the membrane localization of the alpha 1 subunit and the number of cells expressing L-type Ca2+ currents, without affecting the total amount of the expressed alpha 1C subunit. Expression of maximal currents in alpha 1C/beta 2a cotransfected cells paralleled the time course of expression of the beta subunit. Taken together, these results suggest that the beta subunit plays multiple roles in the formation, stabilization, targeting, and modulation of L-type channels.
Amino Acid Sequence↗
TennCare--health system reform for Tennessee.
TennCare, the health care system reform plan implemented in Tennessee on January 1, 1994, was developed with the dual objectives of controlling the rapidly rising cost of the state's Medicaid program and extending health insurance coverage to most Tennesseans without access to employer-sponsored or other government-sponsored health insurance. Beneficiaries enroll in competing, state-chartered managed care organizations that are responsible for providing broad preventive, inpatient, and outpatient services and are reimbursed by the state on a capitation basis at a rate based on a statewide global budget for health care. The program initially proposed to enroll up to 1,775,000 citizens and was projected to result in a cumulative cost savings to Tennessee and the federal government of $7.2 billion by the end of the 5-year demonstration period. However, major start-up problems encountered by the state and by managed care organizations and limitations imposed by the government have significantly constrained these expectations. At the end of its first year, more than 1.2 million citizens were enrolled, but the program incurred a $99 million deficit. Managed care organizations and hospitals have reported major financial problems, and constituency groups--especially those representing physicians--have attempted to block the program. Our objective is to describe the design and rationale of TennCare and discuss key issues the plan continues to face that may affect its long-term success.
Capitation Fee↗
Clinical significance of intratumoral blood flow in cervical carcinoma assessed by color Doppler ultrasound.
BACKGROUND: Much evidence has suggested that vascular density reflects the clinical behavior of cancer. In this study, the intratumoral blood flow in cervical carcinomas was assessed by transvaginal color Doppler ultrasound, and its clinical significance was evaluated. METHODS: Sixty-five patients with Stage Ib-IIb cervical carcinoma exhibiting visible cervical tumor by transvaginal ultrasound were enrolled. All patients were scheduled for radical hysterectomy and pelvic lymph node dissection. Transvaginal color Doppler ultrasound was performed before surgery to search for blood flow signals from the tumor and the main uterine artery. The corresponding arterial resistance index (RI) was calculated. Clinical and pathologic data were recorded. A cytokinetic study was performed by propidium iodide staining and flow cytometry. The human papillomavirus (HPV) status was assessed by polymerase chain reaction. RESULTS: Intratumoral blood flow was detected by color Doppler ultrasound in 46.2% (30/65) of the tumors. Patients with detectable intratumoral blood flow exhibited significantly more pelvic lymph node metastasis (10/30 vs. 2/35, P = 0.005), a higher percentage of cancer cells in the S- + G2M-phase (30.02 +/- 18.54% vs. 19.35 +/- 11.21%, P < 0.005), and a higher prevalence of HPV infection (30/30 vs. 25/35, P = 0.001) when compared with those without intratumoral blood flow. No significant difference was observed concerning the patient's age, tumor size, clinical staging, histologic type, and DNA ploidy status between these two groups. Regression analysis of the intratumoral RI value on the S- + G2M-phase fraction showed linear regression (n = 30, r2 = 0.501, P < 0.01). The RI values of the main uterine artery showed no significant difference between these two groups. CONCLUSION: The intratumoral blood flow by transvaginal color Doppler ultrasound correlated well with a higher proliferation index, higher incidence of HPV infection, and pelvic lymph node metastasis in cervical carcinoma.
Adult↗