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Biomedical subjects

M C Hall

Publications and source records attributed to M C Hall.

At least 19 recordsLinked to original sources
PubMed2005

Relative impact of radiographic osteoarthritis and pain on quadriceps strength, proprioception, static postural sway and lower limb function.

OBJECTIVE: To investigate the relative impact of radiographic osteoarthritis (ROA) and current knee pain on lower limb physical function, quadriceps strength, knee joint proprioception, and postural sway. METHODS: Using a 2x2 factorial design, 142 community derived subjects aged over 45 were divided into four subgroups based on the presence or absence of ROA (Kellgren & Lawrence>grade 2) and knee pain (as assessed by NHANES questions and a 100 mm visual analogue scale). Maximum isometric contraction of the quadriceps, knee joint proprioceptive acuity, static postural sway, and WOMAC index (both whole and function subscale) were assessed in all subjects. RESULTS: Compared with normal subjects, reported disability was greater for all other subgroups (p<0.01). Subjects with both ROA and knee pain reported the greatest disability, and those with knee pain only had greater disability than those with ROA only. Quadriceps weakness was observed in all groups compared with normal subjects (p<0.01), though they were no significant intergroup differences. Subjects with knee pain had a greater sway area than those without (p<0.05) but the presence of ROA was not associated with increased postural sway. No differences in proprioceptive acuity were observed between groups. CONCLUSIONS: The presence of knee pain has a negative association with quadriceps strength, postural sway, and disability compared with ROA. However, the presence of pain-free ROA has a significant negative influence on relative quadriceps strength and reported disability.

Aged↗
PubMed2001

A prospective quality-of-life study in men with clinically localized prostate carcinoma treated with radical prostatectomy, external beam radiotherapy, or interstitial brachytherapy.

PURPOSE: To prospectively assess the health-related quality of life (HRQOL) and changes in HRQOL during the first year after 3 different treatments for clinically localized prostate cancer. METHODS AND MATERIALS: Ninety men with T1-T2 adenocarcinoma of the prostate were treated with curative intent between May 1998 and June 1999 and completed a quality-of-life Functional Assessment of Cancer Therapy-Prostate (FACT-P) questionnaire before treatment (T0) and 1 month (T1), 3 months (T3), and 12 months (T12) after treatment. Forty-four men were treated with permanent source interstitial brachytherapy (IB), 23 received external beam radiotherapy (EBRT), and 23 men were treated with radical prostatectomy (RP). The mean age of the entire study population was 65.9 years (median 67, range 42-79). The mean pretreatment prostate-specific antigen level of the entire study population was 6.81 ng/mL (median 6.25, range 1.33-19.6). The Gleason score was <or=6 in 65 (72%) of 90. The repeated measures analysis of variance and analysis of covariance were conducted on all quality-of-life and urinary outcome measures. RESULTS: A comparison of the demographic characteristics of the 3 treatment groups demonstrated significant differences. The men treated with RP were significantly younger than the men in either the IB or EBRT group (median age 61.0 RP, 67.1 IB, 68.8 EBRT; p = 0.0006). The men in the IB group were more likely to have a Gleason score of <or=6 than the EBRT group (Gleason score <or=6, 86% IB and 48% EBRT; p = 0.015). The mean score (standard deviation) at T0, T1, T3, and T12 for the FACT-P questionnaire for each group was as follows: IB 138.4 (17.0), 120.5 (21.7), 130.0 (18.4), and 138.5 (14.2); EBRT 137.1 (12.1), 129.5 (21.0), 134.4 (19.2), and 136.9 (15.6); and RP 138.3 (14.7), 117.7 (18.3), 134.4 (17.8), and 140.4 (14.9), respectively. Statistically significant differences over time were observed for the FACT-P in the IB and RP groups (p <0.0001), but not for the EBRT group (p = 0.08). The examination of the subscales within the FACT-P instrument demonstrated statistically significant changes over time in the IB and RP groups for the following: physical well-being, functional well-being, and prostate cancer symptoms. After adjusting for age, race, T stage, Gleason score, use of hormonal therapy, and baseline FACT-P scores, statistically significant differences in the FACT-P score at T1 according to treatment group were observed. At T12, the FACT-P scores were not significantly different than the baseline FACT-P scores for any group. CONCLUSIONS: The results of this analysis suggest that significant decreases in HRQOL, as measured by the FACT-P instrument, are evident in the first month after IB or RP, but not after EBRT. One year after treatment, however, the FACT-P scores were not statistically different from the baseline measures for any group. For all treatment groups, most of the HRQOL decreases were observed in the physical, functional, and prostate cancer-specific domains. These results suggest that the HRQOL changes are likely to be treatment-specific, further emphasizing the importance of a randomized trial comparing the different treatment options in this population of men.

Adult↗
PubMed2001

High affinity cooperative DNA binding by the yeast Mlh1-Pms1 heterodimer.

We demonstrate here that the Saccharomyces cerevisiae Mlh1-Pms1 heterodimer required for DNA mismatch repair and other cellular processes is a DNA binding protein. Binding was evaluated using a variety of single and double-stranded DNA molecules. Mlh1-Pms1 bound short substrates with low affinity and showed a slight preference for single-stranded DNA. In contrast, Mlh1-Pms1 exhibited a much higher affinity for long DNA molecules, suggesting that binding is cooperative. High affinity binding required a duplex DNA length greater than 241 base-pairs. The rate of association with DNA was rapid and dissociation of protein-DNA complexes following extensive dilution was very slow. However, in competition experiments, we observed a rapid active transfer of Mlh1-Pms1 from labeled to unlabeled DNA. Binding was non-sequence specific and highly sensitive to salt type and concentration, suggesting that Mlh1-Pms1 primarily interacts with the DNA backbone via ionic contacts. Cooperative binding was observed visually by atomic force microscopy as long, continuous tracts of Mlh1-Pms1 protein bound to duplex DNA. These images also showed that Mlh1-Pms1 simultaneously interacts with two different regions of duplex DNA. Taken together, the atomic force microscope images and DNA binding assays provide strong evidence that Mlh1-Pms1 binds duplex DNA with positive cooperativity and that there is more than one DNA binding site on the heterodimer. These DNA binding properties of Mlh1-Pms1 may be relevant to its participation in DNA mismatch repair, recombination and cellular responses to DNA damage.

Adaptor Proteins, Signal Transducing↗
PubMed2001

Purification of eukaryotic MutL homologs from Saccharomyces cerevisiae using self-affinity technology.

Self-cleaving affinity technology is an effective tool for rapid purification of native sequence recombinant proteins overproduced in Escherichia coli. In this report, we describe the adaptation of this technology to purify DNA mismatch repair proteins overproduced in the eukaryote Saccharomyces cerevisiae. Mlh1 and Pms1 are homologs of the E. coli MutL protein that participate in a variety of DNA transactions in cells, including correction of DNA replication errors, recombination, excision repair, and checkpoint control. Difficulties in preparing substantial quantities of highly purified MutL homologs have impeded descriptions of their biophysical and biochemical properties and mechanisms of action. To overcome this limitation, here we use self-cleaving affinity technology to purify to apparent homogeneity the yeast Mlh1--Pms1 heterodimer and the individual yeast and human Mlh1 subunit. The availability of these proteins should accelerate an understanding of their multiple functions in mismatch repair and other DNA transactions. The general approach is a valid alternative for simple, rapid purification of recombinant proteins in yeast when expression in bacteria is unsuitable.

Adaptor Proteins, Signal Transducing↗
PubMed2001

Inactivation of DNA mismatch repair by increased expression of yeast MLH1.

Inactivation of DNA mismatch repair by mutation or by transcriptional silencing of the MLH1 gene results in genome instability and cancer predisposition. We recently found (P. V. Shcherbakova and T. A. Kunkel, Mol. Cell. Biol. 19:3177-3183, 1999) that an elevated spontaneous mutation rate can also result from increased expression of yeast MLH1. Here we investigate the mechanism of this mutator effect. Hybridization of poly(A)(+) mRNA to DNA microarrays containing 96.4% of yeast open reading frames revealed that MLH1 overexpression did not induce changes in expression of other genes involved in DNA replication or repair. MLH1 overexpression strongly enhanced spontaneous mutagenesis in yeast strains with defects in the 3'-->5' exonuclease activity of replicative DNA polymerases delta and epsilon but did not enhance the mutation rate in strains with deletions of MSH2, MLH1, or PMS1. This suggests that overexpression of MLH1 inactivates mismatch repair of replication errors. Overexpression of the PMS1 gene alone caused a moderate increase in the mutation rate and strongly suppressed the mutator effect caused by MLH1 overexpression. The mutator effect was also reduced by a missense mutation in the MLH1 gene that disrupted Mlh1p-Pms1p interaction. Analytical ultracentrifugation experiments showed that purified Mlh1p forms a homodimer in solution, albeit with a K(d) of 3.14 microM, 36-fold higher than that for Mlh1p-Pms1p heterodimerization. These observations suggest that the mismatch repair defect in cells overexpressing MLH1 results from an imbalance in the levels of Mlh1p and Pms1p and that this imbalance might lead to formation of nonfunctional mismatch repair complexes containing Mlh1p homodimers.

Adaptor Proteins, Signal Transducing↗
PubMed2000

Identification of in-gel digested proteins by complementary peptide mass fingerprinting and tandem mass spectrometry data obtained on an electrospray ionization quadrupole time-of-flight mass spectrometer.

The present study reports a procedure developed for the identification of SDS-polyacrylamide gel electrophoretically separated proteins using an electrospray ionization quadrupole time-of-flight mass spectrometer (Q-TOF MS) equipped with pressurized sample introduction. It is based on in-gel digestion of the proteins without previous reduction/alkylation and on the capability of the Q-TOF MS to provide data suitable for peptide mass fingerprinting database searches and for tandem mass spectrometry (MS/MS) database searches (sequence tags). Omitting the reduction/alkylation step reduces sample contamination and sample loss, resulting in increased sensitivity. Omitting this step can leave disulfide-connected peptides in the analyte that can lead to misleading or ambiguous results from the peptide mass fingerprinting database search. This uncertainty, however, is overcome by MS/MS analysis of the peptides. Furthermore, the two complementary MS approaches increase the accuracy of the assignment of the unknown protein. This procedure is thus, highly sensitive, accurate, and rapid. In combination with pressurized nanospray sample introduction, it is suitable for automated sample handling. Here, we apply this approach to identify protein contaminants observed during the purification of the yeast DNA mismatch repair protein Mlh 1.

Adaptor Proteins, Signal Transducing↗
PubMed2000

Thoracoabdominal radical nephrectomy: is a postoperative thoracostomy tube necessary?

OBJECTIVES: To report our results of patients undergoing thoracoabdominal radical nephrectomy without intraoperative placement of a thoracostomy tube. It has been routine in our hospital to not place a thoracostomy tube in patients undergoing thoracoabdominal radical nephrectomy since 1988. METHODS: We conducted a retrospective review of 47 thoracoabdominal radical nephrectomies performed from January 1988 through November 1998 at our institution. Of the 47 patients, 39 did not have a thoracostomy tube placed intraoperatively; the other 8 patients did. The development of all postoperative complications, length of hospital stay, and hospital charges were noted. RESULTS: No postoperative mortality was noted in our study. Of the 47 patients in the study, 20 patients had a total of 29 complications. The overall number of complications was not increased in the group without a thoracostomy tube compared with the group with a thoracostomy tube (P = 0.104). No patient treated without a thoracostomy tube required subsequent placement of a tube for persistent pneumothorax. The mean length of hospital stay in patients with a thoracostomy tube after radical nephrectomy was 9.14 +/- 2.65 days; in patients without a thoracostomy tube, the mean length of stay was 7.07 +/- 3.97 days (P = 0.071). CONCLUSIONS: In patients without parietal pleural injury, thoracoabdominal radical nephrectomy without the placement of a thoracostomy tube can be performed safely and effectively, with a low risk of postoperative complications and a decrease in the overall hospital stay and hospital charges.

Adult↗
PubMed2000

Ureteroscopic management of patients with upper tract transitional cell carcinoma.

Endoscopic therapy for the management of upper urinary tract TCC is mainly indicated for patients with an anatomically or functionally solitary kidney, renal insufficiency, bilateral tumors, or severe medical comorbidity. It may be a reasonable alternative to distal ureterectomy with bladder-cuff resection in individuals with low-grade superficial distal ureteral tumors. Although use of this approach has been suggested for treating standard patients with low-grade, low-stage collecting system tumors, this recommendation should not be embraced until more supporting evidence is generated. The efficacy of adjuvant therapy for the prevention of recurrent or progressive disease needs to be defined. If current adjuvant strategies prove ineffective, alternative ones will need to be developed. It is anticipated that advancements in endoscopic technology will facilitate the performance of this type of surgery in the future.

Carcinoma in Situ↗
PubMed2000

Bladder cancer.

There is a need for the development of reliable tumor markers in bladder cancer. A number of studies this past year focused on the evaluation of urinary markers that hold promise as noninvasive adjuncts to traditional diagnostic or surveillance techniques, principally urinary cytology and cystoscopy. Tests for bladder tumor antigen, NMP22, and fibrin degradation products, as well as the Immunocyt test, are commercially available. Other urinary marker tests discussed in this review include telomerase, cytokeratins, and vascular endothelial growth factor. Although these tests in many instances have improved sensitivity in detecting bladder cancer compared with urinary cytology, none have become widely accepted in routine clinical practice. Nonetheless, with further refinement and prospective validation in multicenter trials, markers such as these may provide information that would permit tailoring on an individual basis the type of as well as interval of surveillance examinations. Furthermore, they may also provide information allowing the appropriate selection of therapy based on predicted response. In addition to urinary markers, intense research efforts have also focused on developing clinically useful molecular prognostic markers. A number of cell-cycle regulatory proteins, including p53 and p21, have received much attention in this regard. Emerging data suggests that it may soon be possible to determine the molecular phenotype of both superficial and invasive bladder cancers, thereby providing information regarding tumor behavior on an individual basis. As with urinary markers, however, no molecular markers have been incorporated as yet into day-to-day patient care. Assurances of reproducibility, standardization, and prospective validation studies are urgently needed. It is only through this type of rigorous evaluation that the level of confidence sufficient to base treatment decisions on marker status will be attained.

Biomarkers, Tumor↗
PubMed2000

The growth inhibitory effect of p21 adenovirus on human bladder cancer cells.

PURPOSE: To evaluate whether p21 (WAF-1/CIP1) should be considered a potential candidate for human bladder cancer gene therapy, we determined: (1) the basal level of p21 expression in bladder cancer cell lines, (2) the response of bladder cancer cells to increased p21 expression following p21 adenovirus infection, and (3) the mechanism of growth inhibition produced by p21 overexpression. MATERIALS AND METHODS: Five established human bladder cancer cell lines and one primary culture derived from an invasive transitional cell carcinoma were used in this study. To examine the effect of p21 protein on the growth of human bladder cancer cells, a recombinant adenovirus vector system containing p21 cDNA, under the control of cytomegalovirus promoter, was constructed. A control virus containing p21 in an antisense orientation was used to eliminate potential artifacts caused by viral toxicity. RESULTS: Human bladder cancer cell lines exhibit variable endogenous p21 levels which correlate with the in vitro growth status. Significant, but highly variable increases in the steady-state level of p21 were detected in p21 adenovirus infected cells. Human bladder cancer cell lines responded heterogeneously to p21 adenovirus infection. Growth of the WH cell line was substantially inhibited in a dose and time-course dependent fashion. The mechanism of p21 growth inhibition was found to be due to G0/G1 arrest and not the induction of apoptosis. In contrast, p21 adenovirus failed to inhibit the growth of T24 bladder cancer cells because T24 cells were resistant to viral infection. The 253J bladder cancer cells exhibited marked sensitivity to adenovirus; substantial growth inhibition was seen with both sense and antisense p21 very early in the time course of infection. CONCLUSIONS: We found significant variation in the basal level of p21 protein expression in several human bladder cancer cell lines. Increased p21 expression as a result of adenoviral infection may be a potent growth suppressor in some human bladder cancer because it elicits cell cycle arrest in G0/G1 stage, but not the induction of apoptosis. Bladder cancer cells exhibit a wide spectrum of sensitivity to adenoviral infection that may be caused by the presence of viral receptor heterogeneity. This wide spectrum of sensitivity has significant basic scientific and clinical implications and warrants further study.

Adenoviridae↗
PubMed1999

Escherichia coli DNA helicase II is active as a monomer.

Helicases are thought to function as oligomers (generally dimers or hexamers). Here we demonstrate that although Escherichia coli DNA helicase II (UvrD) is capable of dimerization as evidenced by a positive interaction in the yeast two-hybrid system, gel filtration chromatography, and equilibrium sedimentation ultracentrifugation (Kd = 3.4 microM), the protein is active in vivo and in vitro as a monomer. A mutant lacking the C-terminal 40 amino acids (UvrDDelta40C) failed to dimerize and yet was as active as the wild-type protein in ATP hydrolysis and helicase assays. In addition, the uvrDDelta40C allele fully complemented the loss of helicase II in both methyl-directed mismatch repair and excision repair of pyrimidine dimers. Biochemical inhibition experiments using wild-type UvrD and inactive UvrD point mutants provided further evidence for a functional monomer. This investigation provides the first direct demonstration of an active monomeric helicase, and a model for DNA unwinding by a monomer is presented.

Adenosine Triphosphatases↗
PubMed1999

The Escherichia coli MutL protein physically interacts with MutH and stimulates the MutH-associated endonuclease activity.

All possible pairwise combinations of UvrD, MutL, MutS, and MutH were tested using the yeast two-hybrid system to identify potential interactions involving mismatch repair proteins. A two-hybrid screen previously identified a physical interaction between MutL and UvrD. Although several other known interactions were not observed, a novel interaction between MutL and MutH was detected. A series of truncations from the NH2 and COOH termini of MutL demonstrated that the COOH-terminal 218 amino acids were sufficient for the two-hybrid interaction with MutH. Removal of a small number of residues from either the NH2 or COOH termini of MutH eliminated the two-hybrid interaction with MutL. Protein affinity chromatography experiments confirmed that MutL, but not MutS, physically associates with MutH. Furthermore, MutL greatly stimulated the d(GATC)-specific endonuclease activity of MutH in the absence of MutS and a mispaired base. Stimulation of the MutH-associated endonuclease activity by MutL was dependent on ATP binding but not ATP hydrolysis. Further stimulation of this reaction by MutS required the presence of a DNA mismatch and a hydrolyzable form of ATP. These results suggest that MutL activates the MutH-associated endonuclease activity through a physical interaction during methyl-directed mismatch repair in Escherichia coli.

Adenosine Triphosphatases↗
PubMed1999

Loss of adenoviral receptor expression in human bladder cancer cells: a potential impact on the efficacy of gene therapy.

There is great interest in the development of gene therapeutic strategies for the treatment of benign and malignant diseases. Recombinant adenovirus has a wide spectrum of tissue specificity and is an efficient vector delivery system. Successful gene delivery, however, requires viral entry into the target cells via specific receptor-mediated uptake. Recently, a cDNA clone (the coxsackie and adenovirus receptor [CAR]) encoding a 46-kDa protein was identified as the receptor for group C adenovirus (e.g., adenovirus type 2 and 5). Currently, little is known regarding the expression of adenoviral receptor in normal tissue and cancer. In this paper, we have documented a significant difference in viral receptor levels that may be due to transcriptional regulation of the CAR gene in several human bladder cancer cell lines. The differences in viral receptor levels in these cells correlated with their sensitivity to viral infection. Transfection of receptor-negative cell line with CAR cDNA led to increased virus binding and increased susceptibility to adenovirus-mediated gene delivery. Our results demonstrate that the expression of adenoviral receptor is variable among human bladder cancer cells. This variability may have a significant impact on the outcome of adenovirus-based gene therapy.

Adenoviridae↗
PubMed1999

Prospective determination of the hormonal response after cessation of luteinizing hormone-releasing hormone agonist treatment in patients with prostate cancer.

OBJECTIVES: To determine the hormonal (luteinizing hormone [LH] and testosterone) and biochemical (serum prostate-specific antigen [PSA]) response to withdrawal of luteinizing hormone-releasing hormone (LHRH) agonists in patients who received more than 2 years of LHRH therapy for advanced prostate cancer. METHODS: Fourteen patients with clinical Stage T3 or higher prostate cancer and no evidence of clinical or biochemical progression, who had received 2 years or more of LHRH therapy, were enrolled at the time of their scheduled 3-month depot injection. Patients underwent history, physical examination, and measurement of serum PSA, LH, and testosterone at baseline, monthly for 3 months, and then every 3 months for 1 year following LHRH withdrawal. RESULTS: The mean age of patients was 70.3 years (range 56 to 84). Patients previously received LHRH agonist for a mean of 38.6 months (range 25 to 82). All patients had castrate levels of testosterone (median 10.0 ng/dL) and suppressed LH levels (median 0.1 mIU/mL) at baseline. Median baseline PSA was 0.15 ng/mL. On multiple groupwise comparison, there was no significant change (compared with baseline) in LH or testosterone until 6 months after withdrawal and no change in PSA throughout the duration of the study (median PSA at 1 2 months 0.30 ng/mL). Despite significant increases in LH and testosterone when compared with baseline beginning at 6 months, both LH and testosterone remained markedly suppressed, with median testosterone remaining in the castrate range at both 6 and 9 months and significantly below the lower limit of normal at 12 months (median 111.0 ng/dL). Despite no statistically significant change for the entire cohort in serum PSA, a rising PSA was noted in 4 patients between 3 and 9 months, and LHRH therapy was reinitiated. The remaining patients continued to have suppressed LH and testosterone, with 4 patients remaining in the castrate range at 12 months. CONCLUSIONS: The recovery of function of the hypothalamic-pituitary-testicular axis after prolonged LHRH administration is variable. Castrate levels of testosterone and suppressed LH may persist even up to 1 year after discontinuing LHRH. These results have significant implications regarding the interpretation of clinical trials incorporating neoadjuvant and adjuvant hormonal therapy. Further studies are needed to expand on these preliminary observations and should also address the feasibility of incorporating LHRH withdrawal into clinical practice.

Aged↗
PubMed1999

Recent advances in the treatment of prostate cancer.

As new evidence for prostate cancer treatment has emerged in the last few years, longstanding controversies in the treatment of prostate cancer have resurfaced. A number of long-held tenets of prostate cancer therapy have been revisited, sometimes with surprising and challenging results. Although neoadjuvant hormonal therapy prior to radical prostatectomy decreases positive surgical margin rates, longer follow-up is needed to support survival improvement of this combined modality therapy. Androgen deprivation combined with radiation therapy appears to improve disease-free survival (and survival in one series) in patients with locally advanced cancer. Another approach to locally advanced prostate cancer using three-dimensional conformal radiation therapy may improve long term outcome. The data are currently insufficient to conclude that interstitial low dose rate brachytherapy is equivalent to conventional treatments: patients with small tumor volumes and low Gleason grade seem to obtain more benefit, whereas for large tumors with higher gleason grades this approach seems inferior to conventional treatments. In advanced prostate cancer recent data suggest that immediate hormonal therapy improves survival. In this group of patients the use of maximum androgen blockade remains controversial but may adversely affect quality of life compared to orchiectomy alone. Intermittent hormonal therapy may improve quality of life, although effect upon survival is unknown. Chemotherapy in combination with androgen deprivation is currently being studied as front-line therapy in advanced prostate cancer. Palliative benefit of chemotherapy for hormone refractory prostate cancer remains an important endpoint; survival advantage has not been seen in any randomized trials. Suramin may delay disease progression in hormone refractory prostate cancer. Many aspects of prostate cancer treatment will remain controversial until results of large, randomized trials with longer follow-up are available.

Antineoplastic Agents, Hormonal↗