Postmastectomy CT-based electron beam radiotherapy: Dosimetry, efficacy, and toxicity in 118 patients

PURPOSE

To evaluate the technique, dosimetry, acute and late toxicity, local control (LC), and overall survival (OS) with the use of computed tomography (CT)-based postmastectomy electron beam therapy (PMEBT) in high-risk patients.

METHODS AND MATERIALS

From 1990 to 2000, 118 patients with pathologic stage I-IIIB breast cancer underwent PMEBT of the chest wall (CW) (n = 3), CW and supraclavicular fossa (SCV) (n = 63), CW, SCV, and internal mammary lymph nodes (IMN) (n = 51), and SCV+IMN (n = 1). Radiation therapy was delivered with an en face electron beam with a custom cutout. Treatment plans were all CT-based. The plans of 16 patients were retrospectively reviewed to analyze dosimetry data. A retrospective chart review was conducted to assess acute and late complications, LC, and OS.

RESULTS

At a median follow-up of 43 months, 5-year LC and OS were 91% and 61%, respectively. Sixty-one patients developed acute grade 3-4 skin toxicity, necessitating treatment breaks in 33 patients. Fifteen patients experienced a worsening of lymphedema, and 2 patients developed cardiac injury thought to be unrelated to radiotherapy. No patients developed symptomatic pneumonitis. Dosimetric analysis revealed heart and lung normal tissue complication probabilities of zero. Analysis of other clinically relevant dosimetric parameters revealed PMEBT to be comparable to previously reported techniques.

CONCLUSION

Postmastectomy electron beam therapy is an effective way to deliver radiation to the postmastectomy chest wall and adjacent nodal sites. It offers acceptable acute and late toxicities and a high degree of local control given the high-risk population to which it is offered.

Salvage radiotherapy for recurrent prostate cancer after radical prostatectomy

CONTEXT

Salvage radiotherapy may potentially cure patients with disease recurrence after radical prostatectomy, but previous evidence has suggested that it is ineffective in patients at the highest risk of metastatic disease progression.

OBJECTIVE

To delineate patients who may benefit from salvage radiotherapy for prostate cancer recurrence by identifying variables associated with a durable response.

DESIGN, SETTING, AND PATIENTS

Retrospective review of a cohort of 501 patients at 5 US academic tertiary referral centers who received salvage radiotherapy between June 1987 and November 2002 for detectable and increasing prostate-specific antigen (PSA) levels after radical prostatectomy.

MAIN OUTCOME MEASURE

Disease progression after salvage radiotherapy, defined as a serum PSA value > or =0.1 ng/mL above the postradiotherapy PSA nadir confirmed by a second PSA measurement that was higher than the first by any amount, by a continued increase in PSA level after treatment, or by the initiation of androgen deprivation therapy after treatment.

RESULTS

Over a median follow-up of 45 months, 250 patients (50%) experienced disease progression after treatment, 49 (10%) developed distant metastases, 20 (4%) died from prostate cancer, and 21 (4%) died from other or unknown causes. The 4-year progression-free probability (PFP) was 45% (95% confidence interval [CI], 40%-50%). By multivariable analysis, predictors of progression were Gleason score of 8 to 10 (hazard ratio [HR], 2.6; 95% CI, 1.7-4.1; P<.001), preradiotherapy PSA level greater than 2.0 ng/mL (HR, 2.3; 95% CI, 1.7-3.2; P<.001), negative surgical margins (HR, 1.9; 95% CI, 1.4-2.5; P<.001), PSA doubling time (PSADT) of 10 months or less (HR, 1.7; 95% CI, 1.2-2.2; P =.001), and seminal vesicle invasion (HR, 1.4; 95% CI, 1.1-1.9; P =.02). Patients with no adverse features had a 4-year PFP of 77% (95% CI, 64%-91%). When treatment was given for early recurrence (PSA level < or =2.0 ng/mL), patients with Gleason scores of 4 to 7 and a rapid PSADT had a 4-year PFP of 64% (95% CI, 51%-76%) and of 22% (95% CI, 6%-38%) when the surgical margins were positive and negative, respectively. Patients with Gleason scores of 8 to 10, positive margins, and receiving early salvage radiotherapy had a 4-year PFP of 81% (95% CI, 57%-100%) when the PSADT was longer than 10 months and of 37% (95% CI, 16%-58%) when the PSADT was 10 months or less.

CONCLUSIONS

Gleason score, preradiotherapy PSA level, surgical margins, PSADT, and seminal vesicle invasion are prognostic variables for a durable response to salvage radiotherapy. Selected patients with high-grade disease and/or a rapid PSADT who were previously thought to be destined to develop progressive metastatic disease may achieve a durable response to salvage radiotherapy.

Development of a semi-automatic alignment tool for accelerated localization of the prostate

PURPOSE

Delivering high dose to prostate with external beam radiation has been shown to improve local tumor control. However, it has to be carefully performed to avoid partial target miss and delivering excessive dose to surrounding normal tissues. One way to achieve safe dose escalation is to precisely localize prostate immediately before daily treatment. Therefore, the radiation can be accurately delivered to the target. Once the prostate position is determined with high confidence, planning target volume (PTV) safety margin might be reduced for further reduction of rectal toxicity. A rapid computed tomography (CT)-based online prostate localization method is presented for this purpose.

METHODS AND MATERIALS

Immediately before each treatment session, the patient is immobilized and undergoes a CT scan in the treatment position using a CT scanner situated in the treatment room. At the CT console, posterior, anterior, left, and right extents of the prostate are manually identified on each axial slice. The translational prostate displacements relative to the planned position are estimated by simultaneously fitting these identified extents from this CT scan to a template created from the finely sliced planning CT scan. A total of 106 serial CT scans from 8 prostate cancer patients were performed immediately before treatments and used to retrospectively evaluate the precision of this daily prostate targeting method. The three-dimensional displacement of the prostate with respect to its planned position was estimated.

RESULTS

Five axial slices from each treatment CT scan were sufficient to produce a reliable correction when compared with prostate center of gravity (CoG) displacements calculated from physician-drawn contours. The differences (mean +/- SD) between these two correction schemes in the right-left (R/L), posterior-anterior (P/A), and superior-inferior (S/I) directions are 0.0 +/- 0.4 mm, 0.0 +/- 0.7 mm, and -0.4 +/- 1.9 mm, respectively. With daily CT extent-fitting correction, 97% of the scans showed that the entire posterior prostate gland was covered by PTV given a margin of 6 mm at the rectum-prostate interface and 10 mm elsewhere. In comparison, only 74% and 65% could be achieved by the corrections based on daily and weekly bony matching on portal images, respectively.

CONCLUSIONS

Results show that daily CT extent fitting provides a precise correction of prostate position in terms of CoG. Identifying prostate extents on five axial CT slices at the CT console is less time-consuming compared with daily contouring of the prostate on many slices. Taking advantage of the prostate curvature in the longitudinal direction, this method also eliminates the necessity of identifying prostate base and apex. Therefore, it is clinically feasible and should provide an accelerated localization of the prostate immediately before daily treatment.

Predictors of biochemical outcome with salvage conformal radiotherapy after radical prostatectomy for prostate cancer

PURPOSE

To identify predictors of biochemical outcome following radiotherapy in patients with a rising prostate-specific antigen (PSA) after radical prostatectomy for prostate cancer.

PATIENTS AND METHODS

One hundred fifteen patients with a rising PSA after radical prostatectomy received salvage three-dimensional conformal radiotherapy (3D-CRT) alone or with neoadjuvant androgen deprivation. Tumor-related and treatment-related factors were evaluated to identify predictors of subsequent PSA failure.

RESULTS

The median follow-up time after 3D-CRT was 42 months. The 4-year actuarial PSA relapse-free survival, distant metastasis-free survival, and overall survival rates were 46%, 83%, and 95%, respectively. Multivariate analysis, which was limited to 70 patients receiving radiation without androgen deprivation therapy, showed that negative/close margins (P =.03), absence of extracapsular extension (P <.01), and presence of seminal vesicle invasion (P <.01) were independent predictors of PSA relapse after radiotherapy. Neoadjuvant androgen deprivation did not improve the 4-year PSA relapse-free survival in patients with positive margins, extracapsular extension, and no seminal vesicle invasion (P =.24). However, neoadjuvant androgen deprivation did improve PSA relapse-free survival when one or more of these variables were absent (P =.03).

CONCLUSIONS

Salvage 3D-CRT can provide biochemical control in selected patients with a rising PSA after radical prostatectomy. Among patients with positive margins and no poor prognostic features, 77% achieved PSA control after salvage 3D-CRT. Salvage neoadjuvant androgen deprivation therapy may improve short-term biochemical control, but it requires further study.

Translational regulation is a control point in RUNX2/Cbfa1 gene expression

Runt-related transcription factor-2 (RUNX2)/core binding factor a1 (Cbfa1) is implicated in the regulation of osteoblast differentiation and osteoblast-specific gene expression. Mutations in RUNX2 cause the bone disease cleidocranial dysplasia, which is characterized by multiple skeletal defects. RUNX2 is expressed as two isoforms (type-I and type-II) encoded by two different mRNAs. We report here the detection of both mRNAs in osteoblastic cells and osteoblast precursors as well as nonosteoblastic cells. Surprisingly, however, osteoblast precursors and nonosteoblastic cells express no RUNX2 protein; mature osteoblasts express both isoforms, while less mature osteoblastic cells express only type-I protein. Northern blot analysis of RNA isolated from polysomes and ribonucleoprotein particles demonstrated that RUNX2 mRNA is polysome-associated in osteoblastic cells but polysome-free in osteoblast precursors. These results suggest that (a) RUNX2 mRNAs are expressed but dormant in osteoblast precursors and nonosteoblastic cells, (b) RUNX2 gene expression is controlled at the translational level, and (c) the expression of individual protein isoforms of RUNX2 is differentiation stage specific. Thus, differentiation of cells along the osteoblast lineage appears to be regulated at the level of RUNX2 mRNA translation.

Analysis of type-I and type-II RUNX2 protein expression in osteoblasts

Runt-related transcription factor-2 (RUNX2) is expressed as two isoforms (type-I and type-II) differing only in their amino terminal sequences. The amino terminus of type-I contains MRIPV instead of MASNSLFSAVTPCQQSFFW in type-II. Although type-II mRNA has been considered osteoblast specific, the RUNX2 protein isoforms expressed in osteoblasts have not yet been identified. Using antisera generated against the two different amino terminal sequences of type-I and type-II RUNX2, we show the expression of both isoforms in cells with the mature osteoblast phenotype (fetal rat calvarial cells, and ROS 17/2.8, SaOS-2 and U2OS osteosarcoma cell lines), but only type-I in partially differentiated osteoblast-like cells (the UMR-106 osteosarcoma cell line). Since UMR-106 cells express both type-I and type-II mRNAs, our results suggest that the translation of type-II mRNA is repressed in these cells. No RUNX1 and RUNX3 proteins are detected in any of the osteoblastic cells tested. The antisera we have generated will be useful for studies relating expression of RUNX2 isoforms to control of osteoblast differentiation.

Succinylcholine pretreatment using gallamine or mivacurium during rapid sequence induction in children: a randomized, controlled study

STUDY OBJECTIVE

To determine if pretreatment with either gallamine or mivacurium before succinylcholine in children is associated with reduction in fasciculations; postoperative myalgias; or serum levels of potassium, creatinine phosphokinase (CPK), and myoglobin.

DESIGN

Prospective, randomized, double-blinded study.

SETTING

Operating room at a children's hospital.

PATIENTS

45 ASA physical status IE children, aged 3 to 15 years, scheduled for emergency surgery.

INTERVENTIONS

The children received either normal saline 0.5 mL, mivacurium chloride 0.03 mg. kg(-1), or gallamine triethiodide 0.04 mg. kg(-1)2 minutes prior to rapid sequence induction (RSI) using thiopental sodium 5 mg. kg(-1), fentanyl 2 microg. kg(-1), and succinylcholine 2 mg. kg(-1).

MEASUREMENTS

Serum potassium concentration (0, 3, 5, 7.5, and 15 min), myoglobin concentration (5 and 15 min), and CPK concentration (0 min and 24 hr). Fasciculation and myalgia were rated on a 0 to 3 score.

MAIN RESULTS

There was no difference between groups for fasciculation (p = 0.87) or myalgia score (p = 0.52). The mivacurium group had significantly less increase in potassium at 5 minutes (0.45 vs. 0.0, p = 0.01), myoglobin at 5 minutes (56 vs. 2, p < 0.001), myoglobin at 15 minutes (128 vs. 2.5, p < 0.001), and CPK at 24 hours (399 vs. 138, p < 0.001) following succinylcholine when compared with normal saline. Additionally, we found a significant level of association (p < 0.001) between fasciculation and myoglobin levels and fasciculation and CPK levels (p < 0.001). Gallamine was not effective in reducing the increase of potassium, myoglobin, or CPK. However, the dose of gallamine used for pretreatment was 13 times less than the dose of mivacurium.

CONCLUSIONS

Administration of mivacurium 0.03 mg. kg(-1) intravenously 2 minutes before administration of succinylcholine 2 mg. kg(-1) in children is effective in reducing the increase in serum potassium at 5 minutes, the increase in myoglobin at 5 minutes and 15 minutes, and the increase in CPK at 24 hours.

G-protein signaling abnormalities mediated by CD95 in salivary epithelial cells

Salivary epithelial cells from patients with primary Sjögren's syndrome (SS) undergo Fas-mediated apoptosis. Bcl-2 and Bcl-xL are apoptosis suppressing oncogenes. Very little is known about the role of these oncogene molecules in salivary epithelial cells. To investigate the possible prevention of salivary glandular destruction in SS by Bcl-2 and Bcl-xL, stable transfectants expressing these molecules were made from HSY cells, a human salivary epithelial cell line. HSY cells were transfected with an expression vector for human Bcl-2 or Bcl-xL. Stable transfectants were selected and apoptosis was induced by anti-Fas antibody. Apoptosis was quantified by propidium iodide staining followed by flow cytometry. Caspase activity was detected by immunohistochemical analysis and enzyme cleavage of DEVD-AMC, a fluorescent substrate. Response to carbachol, a muscarinic receptor agonist, and EGF was measured by Ca2+ mobilization and influx. Fas-mediated apoptosis was significantly inhibited in Bcl-2 and Bcl-xL transfectants compared to wild-type and control transfectants (empty vector). Surprisingly, caspase activity was not inhibited in Bcl-2 and Bcl-xL transfectants. Activation of the Fas pathway in the Bcl-2 and Bcl-xL transfectants by antibody also inhibited carbachol and EGF responsiveness (i.e., Ca2+ mobilization and/or influx) by 50-60%. This Fas-mediated inhibition of cell activation was partially or completely restored by specific peptide interference of caspase enzyme activity. The prevention of Fas-mediated apoptosis by the overexpression of Bcl-2 and Bcl-xL in salivary gland epithelial cells results in injured cells expressing caspase activity and unable to respond normally to receptor agonists. Such damaged cells may exist in SS patients and could explain the severe dryness out of proportion to the actual number of apoptotic cells seen on salivary gland biopsy.

Geriatrics grand rounds: Eve's rib, or a revisionist view of osteoporosis in men

It is widely accepted that estrogen withdrawal following menopause predisposes women to accelerated bone loss and increased risk of developing osteoporosis. Although osteoporosis is a significant public health problem for aging men as well as women, the cause of osteoporosis in men remains largely unknown. A substantial number of men with osteoporosis present with bone loss secondary to conditions associated with reduced gonadal steroid hormone levels. Although hypogonadism is related to bone loss in men, and androgen levels decline with age in men, it is not at all clear that reduced androgen levels are related to bone loss in older men. What, then, is the role of gonadal steroids in osteoporosis in men? This review focuses on recent research--including clinical investigations of men with genetic disorders of estrogen action, basic biomedical studies of estrogen receptor "knockout" mice, and population-based comparisons of bone density with gonadal steroids in older men--leading to the surprising conclusion that estrogen plays a vital role in maintenance of bone in men as well as in women. Possible mechanisms whereby reduced estrogen levels might result in bone loss in both sexes are also reviewed, as are potential therapeutic implications of a role for estrogen in osteoporosis in men.

EGF inhibits muscarinic receptor-mediated calcium signaling in a human salivary cell line

The effects of epidermal growth factor (EGF) on intracellular calcium ([Ca(2+)](i)) responses to the muscarinic agonist carbachol were studied in a human salivary cell line (HSY). Carbachol (10(-4) M)-stimulated [Ca(2+)](i) mobilization was inhibited by 40% after 48-h treatment with 5 x 10(-10) M EGF. EGF also reduced carbachol-induced [Ca(2+)](i) in Ca(2+)-free medium and Ca(2+) influx following repletion of extracellular Ca(2+). Under Ca(2+)-free conditions, thapsigargin, an inhibitor of Ca(2+) uptake to internal stores, induced similar [Ca(2+)](i) signals in control and EGF-treated cells, indicating that internal Ca(2+) stores were unaffected by EGF; however, in cells exposed to thapsigargin, Ca(2+) influx following Ca(2+) repletion was reduced by EGF. Muscarinic receptor density, assessed by binding of the muscarinic receptor antagonist L-[benzilic-4,4'-(3)HCN]quinuclidinyl benzilate ([(3)H]QNB), was decreased by 20% after EGF treatment. Inhibition of the carbachol response by EGF was not altered by phorbol ester-induced downregulation of protein kinase C (PKC) but was enhanced upon PKC activation by a diacylglycerol analog. Phosphorylation of mitogen-activated protein kinase (MAP kinase) and inhibition of the carbachol response by EGF were both blocked by the MAP kinase pathway inhibitor PD-98059. The results suggest that EGF decreases carbachol-induced Ca(2+) release from internal stores and also exerts a direct inhibitory action on Ca(2+) influx. A decline in muscarinic receptor density may contribute to EGF inhibition of carbachol responsiveness. The inhibitory effect of EGF is mediated by the MAP kinase pathway and is potentiated by a distinct modulatory cascade involving activation of PKC. EGF may play a physiological role in regulating muscarinic receptor-stimulated salivary secretion.

Accuracy of dipyridamole SPECT imaging in identifying individual coronary stenoses and multivessel disease in women versus men

BACKGROUND

Older women frequently undergo dipyridamole perfusion imaging and can have advanced coronary artery disease, but little data exist on the accuracy of perfusion imaging in detecting disease in individual vascular territories and multivessel disease in women, compared with men.

METHODS AND RESULTS

From a database of patients undergoing myocardial single photon emission computed tomography (SPECT) perfusion imaging, 107 unselected sequential patients (58 women, 49 men) who underwent sestamibi dipyridamole stress and cardiac catheterization within 6 months of each other were identified. Data were analyzed to compare sensitivities for detection of individual coronary stenoses and multivessel disease. The concordance between perfusion image results and cardiac catheterization for individual coronary territories for women was 75%, and for men, it was 65% (P = .09). In women, the presence of disease of the left anterior descending coronary artery was detected more frequently than it was in men, 84% versus 44% (P = .004). The detection of disease in the territories of the left circumflex and right coronary arteries was similar for both groups. For women, the accuracy of perfusion imaging in identifying the presence/absence of multivessel coronary disease was 64%, compared with 71 % for men (P = not significant).

CONCLUSIONS

The accuracy of dipyridamole sestamibi SPECT imaging in detecting multivessel disease was similar for men and women. The sensitivity of dipyridamole sestamibi SPECT imaging in detecting disease of the left anterior descending artery was better in women.

Activation of PLC and PI 3 kinase by PDGF receptor alpha is not sufficient for mitogenesis and migration in mesangial cells

BACKGROUND

Platelet-derived growth factor (PDGF) isoforms act through two distinct cell surface alpha and beta receptors. Glomerular mesangial cells express both receptors. PDGF BB and AB are potent mitogens for glomerular mesangial cells, and PDGF BB stimulates cell migration in a phosphatidylinositol 3 (PI 3) kinase-dependent manner. In this study, we investigated the effect of PDGF AA on cell migration, PI 3 kinase and phospholipase C (PLC) activation, and the role of these two enzymes in mediating biological responses in these cells in response to all three isoforms.

METHODS

3H-thymidine incorporation and modified Boyden chamber assay were used to determine DNA synthesis and directed migration, respectively, in response to all three PDGF isoforms. Differential activation of alpha and beta receptors was studied by immunecomplex tyrosine kinase assay of corresponding receptor immunoprecipitates. PLC gamma 1 activity was determined by measuring total inositol phosphates in response to different PDGF isoforms. PI 3 kinase activity was determined in antiphosphotyrosine or PDGF receptor immunoprecipitates.

RESULTS

Both PDGF BB and AB resulted in stimulation of DNA synthesis and directed migration of mesangial cells. AA was neither chemotactic nor mitogenic. However, all three isoforms increased tyrosine phosphorylation of a 180 kD protein in antiphosphotyrosine immunoprecipitates, suggesting activation of respective receptors. Direct immunecomplex tyrosine kinase assay of alpha and beta receptors demonstrated significant activation of both of these receptors when cells are treated with PDGF BB or AB. PDGF AA increased tyrosine kinase activity of the alpha receptor but not the beta receptor. All three isoforms significantly stimulated the production of inositol phosphates with order of potency being BB > AB > AA. PDGF AA also dose dependently stimulated PI 3 kinase activity measured in antiphosphotyrosine immunoprecipitates of treated cells. A comparison of PI 3 kinase activity in antiphosphotyrosine immunoprecipitates from mesangial cells stimulated with three different PDGF isoforms showed significant activation of this enzyme with a decreasing order of activity: BB > AB > AA.

CONCLUSION

Taken together, these data demonstrate that all three isoforms of PDGF significantly stimulate PLC gamma 1 and PI 3 kinase, two enzymes necessary for both DNA synthesis and directed migration. However, activation of alpha receptor by PDGF AA with a subsequent increase in PLC and PI 3 kinase activities is not sufficient to induce these biological responses in mesangial cells. These data indicate that the extent of activation of signal transduction pathways may be a major determinant of the biological activity of different PDGF isoforms in mesangial cells.

The potency of succinylcholine in obese adolescents

We constructed a single-dose response curve for succinylcholine in 30 obese adolescents during thiopental-fentanyl anesthesia administration by using 100 microg/kg, 150 microg/kg, or 250 microg/kg IV. The maximal response (percent depression of neuromuscular function) of the adductor pollicis to supramaximal train-of-four stimuli was recorded by using a Datex (Helsinki, Finland) relaxograph. Linear regression and inverse prediction were used to determine doses of succinylcholine to produce 50% (ED(50)), 90% (ED(90)), and 95% (ED(95)) depression of neuromuscular function. The ED(50), ED(90), and ED(95) were 152.8 microg/kg (95% confidence interval: 77.8-299.5), 275.4 microg/kg (95% confidence interval: 142-545.7), and 344.3 microg/kg (95% confidence interval: 175.3-675. 3), respectively. This ED(50) is similar to the dose reported for similarly aged, nonobese adolescents, 147 microg/kg. The previously reported ED(95) for succinylcholine in nonobese adolescents, 270 microg/kg, is within the 95% confidence interval generated for ED(95) in our study.

IMPLICATIONS

The potency estimates for succinylcholine in obese (body mass index > 30 kg/m(2)) adolescents are comparable to those in similarly aged nonobese adolescents when dosing is calculated based on total body mass and not lean body mass. When a rapid sequence induction of anesthesia is considered in an obese adolescent, the dose of succinylcholine should be based on actual (not lean) body mass.

Patterns of recurrence and outcome for patients with clinical stage II non-small-cell lung cancer

Forty-six patients with pathologic clinical stage II non-small-cell lung carcinoma underwent resection with or without adjuvant radiotherapy from 1989 through 1994. These patients were analyzed to determine patterns of recurrence and survival. Surgery consisted of pneumonectomy for 11 patients, bilobectomy for two patients, lobectomy for 29 patients, and wedge or segmental resection for four patients. Adjuvant radiotherapy was delivered to 29 patients, and the median total dose was 54 Gy (range, 44-60 Gy). Median follow-up time was 23 months for all patients and 25 months for surviving patients. Twenty-six of 46 patients have had recurrence. The site of first recurrence was locoregional for 9 of 46 patients (20%) and distant for 17 of 46 patients (37%). The median time to locoregional recurrence was 18 months for patients treated with radiotherapy and 13 months for patients treated without radiotherapy. An isolated locoregional recurrence (with no simultaneous distant recurrence) was seen in 2 of 28 evaluable patients (7%) treated with radiotherapy compared with 3 of 17 patients (18%) not treated with radiotherapy. For all patients, the 3-year disease-free survival rate was 52%, and the overall survival rate was 52%. Among patients treated with radiotherapy, the 3-year disease-free survival and overall survival rates were 56% and 56%, respectively, compared with 46% and 43%, respectively, for patients who did not receive radiotherapy (p values were not significant). The locoregional recurrence rate was 33% for patients with adenocarcinoma and 15% for those with squamous cell carcinoma. The distant recurrence rates by histologic characteristic were 56% and 20%, respectively. For patients with clinical stage II non-small-cell lung cancer, postoperative radiotherapy appears to improve locoregional control. However, the preponderance of recurrences remains distant. Further study is warranted with special emphasis on control of systemic disease.

Modulation by food restriction of intracellular calcium signaling in parotid acinar cells of aging Fischer 344 rats

Previous studies suggest that alpha 1-adrenergic (alpha 1-AR)-induced intracellular calcium ([Ca2+]i) mobilization in rat parotid acinar cells declines with age. In this study, we examined the effects of food restriction on alpha 1-AR and muscarinic-stimulated [Ca2+]i mobilization in parotid acinar cells during aging. [Ca2+]i levels in response to the alpha 1-AR agonist epinephrine and the muscarinic agonist carbachol were evaluated in Fura-2-loaded parotid acinar cells from ad libitum-fed (AL) and food-restricted (FR) Fischer 344 male rats at 4, 6, 14, and 24 months of age. [Ca2+]i responses to epinephrine and carbachol (10 microM) were significantly reduced (48% and 35%, respectively; p < .05) in cells from 24-month-old AL rats as compared to younger AL rats. In contrast, no significant reduction of epinephrine and carbachol responses was observed in 24-month-old FR animals. An age-related increase in basal [Ca2+]i (peak around 14 months; p < .02) was observed in both AL and FR rats. In addition, basal [Ca2+]i was higher in FR than in AL rats at 14 and 24 months of age (p < .02). These studies suggest that FR partially attenuates or delays age-related impairments in alpha 1-AR- and muscarinic-cholinergic signal transduction systems of parotid acinar cells. Basal [Ca2+]i also appears to be altered during aging and by FR.

Elevated levels of albumin in soleus and diaphragm muscles of mdx mice

Muscle damage is often associated with an influx of extracellular fluid containing albumin into the muscle. Muscles affected by muscular dystrophy undergo severe muscle damage; therefore, the hypothesis was tested that muscles of dystrophic (mdx) mice contain elevated levels of albumin. Albumin levels in diaphragm (DIA) and soleus (SOL) muscles of control and mdx mice were measured at 3 months and 1 year of age. Albumin in mdx DIA at 1 year of age was twice that of control. In mdx SOL at 1 year of age albumin was increased 25% compared with control. The increase in albumin correlates well with the decline in function in mdx DIA and SOL muscles. Electron microscopy of muscles suggests that albumin is co-localized with transverse tubules of muscle fibers and thus may be mainly located in extracellular fluid. We conclude that albumin is elevated in muscles affected by muscular dystrophy and suggest that this may be of clinical importance in view of substances bound to albumin under physiological conditions.

Alterations of adenylyl cyclase-linked G proteins in rat liver during aging

beta-Adrenergic stimulation of adenylyl cyclase in rat liver increases during aging. We examined whether this increase is related to alterations in the stimulatory and inhibitory G proteins (Gs and Gi) linked to adenylyl cyclase. Levels of immunoreactive alpha- and beta-subunits of Ga and Gi in liver plasma membranes from 6-, 12-, 18-, and 24-mo-old rats were unchanged with age, as was pertussis toxin-catalyzed [32P]ADP ribosylation of Gi alpha. Cholera toxin-catalyzed [32P]ADP ribosylation of Ga alpha and Gs bioactivity, assessed as reconstitution of adenylyl cyclase activity in S49 cyc- cell membranes, increased two- to threefold between 6 and 12-18 mo, and declined by 24 mo. Recombinant ADP ribosylation factor (ARF) enhanced cholera toxin labeling of Gs alpha at all ages, yet abolished the increase in toxin labeling at 12-18 mo. Auto-ADP ribosylation of the cholera toxin A1 peptide also increased transiently with age. Alteration of Gs alpha, as reflected by increased cholera toxin labeling and Gs bioactivity, may be involved in the regulation of beta-adrenergic-responsive adenylyl cyclase in rat liver during aging. Moreover, changes in endogenous ARF levels could contribute to age differences in cholera toxin labeling of Gs alpha.

Beneficial versus adverse effects of long-term use of clenbuterol in mdx mice

Long-term administration of the beta 2-adrenergic agonist clenbuterol in mdx mice was used to test the hypothesis that increasing contractile protein content in skeletal muscle will decrease the progression of muscular dystrophy. C57BL/10SNJ (control) and dystrophic (mdx) mice were given clenbuterol (1.0-1.5 mg/kg body weight/day) in the drinking water. Ventilatory function and morphological and functional characteristics of soleus (SOL) and diaphragm (DIA) muscles were evaluated. Clenbuterol administration was associated with increased SOL muscle weight, and SOL muscle weight to body weight ratio in control and mdx mice at both ages. There was a 22% increase in myosin concentration of mdx DIA at 1 year of age, correlating well with increased normalized active tension in mdx DIA at this age. Also, absolute tetanic tension increased in control and mdx SOL with clenbuterol at both ages. Ventilatory function was significantly impaired in mdx mice at both ages and clenbuterol administration did not alleviate this. Clenbuterol treatment was associated with a 30-40% increase in fatigability in DIA and SOL muscles of control and mdx mice at both ages. Furthermore, 1-year-old mdx mice receiving clenbuterol exhibited deformities in hindlimbs and spine. These results suggest that long-term clenbuterol treatment has a positive effect on muscle growth and force generation, but has adverse side effects such as increased muscle fatigability and development of deformities.

Escaping the cave to dream new dreams: a normative vision for learning disabilities

This essay is predicated on two beliefs: (a) that special educators must critically examine the dominant view of reality undergirding the field of learning disabilities to see the false images built into it, and (b) we must seek a new, empowering vision of the purposes of education as we move into the twenty-first century. The purpose of the article is to analyze how the dominant image of reality in the field of learning disabilities is derived from the diagnostic model, and to propose an alternative, normative conception of education that emphasizes the importance of caring, social relatedness, and community participation.

Voluntary exercise decreases progression of muscular dystrophy in diaphragm of mdx mice

Effects of voluntary wheel running on contractile properties of diaphragm (DIA) and soleus (SOL) of dystrophic (mdx) and control (C57BL/10SNJ) mice were evaluated. In particular, we tested the hypothesis that daily voluntary running is not deleterious to muscle function in mdx mice. Both groups of mice ran extensively (control mice approximately 7 km/day, mdx mice approximately 5 km/day). Exercise increased maximal specific tetanus tension of mdx DIA from 1.02 +/- 0.04 to 1.33 +/- 0.06 kg/cm2 but did not restore it to the control level (2.55 +/- 0.17 kg/cm2). Maximal tetanus tension of sedentary mdx SOL (2.41 +/- 0.17 kg/cm2) was reduced compared with control (3.10 +/- 0.15 kg/cm2) and was not altered by running activity. Optimal length was significantly lower in DIA of mdx mice, and exercise did not change this. Fatigability and contractile properties of muscles measured in vitro were not altered by running activity with the exception of increased contraction time in mdx DIA. In conclusion, extensive wheel running is not deleterious to muscle function in mdx mice contrary to predictions of the "work overload" theory of muscular dystrophy. Rather, this exercise is beneficial for active tension generation of mdx DIA, the muscle most closely resembling muscles of patients with Duchenne muscular dystrophy.