Development and reliability of a system to classify gross motor function in children with cerebral palsy

To address the need for a standardized system to classify the gross motor function of children with cerebral palsy, the authors developed a five-level classification system analogous to the staging and grading systems used in medicine. Nominal group process and Delphi survey consensus methods were used to examine content validity and revise the classification system until consensus among 48 experts (physical therapists, occupational therapists, and developmental pediatricians with expertise in cerebral palsy) was achieved. Interrater reliability (kappa) was 0.55 for children less than 2 years of age and 0.75 for children 2 to 12 years of age. The classification system has application for clinical practice, research, teaching, and administration.

The revised UCLA Loneliness Scale: concurrent and discriminant validity evidence

The development of an adequate assessment instrument is a necessary prerequisite for social psychological research on loneliness. Two studies provide methodological refinement in the measurement of loneliness. Study 1 presents a revised version of the self-report UCLA (University of California, Los Angeles) Loneliness Scale, designed to counter the possible effects of response bias in the original scale, and reports concurrent validity evidence for the revised measure. Study 2 demonstrates that although loneliness is correlated with measures of negative affect, social risk taking, and affiliative tendencies, it is nonetheless a distinct psychological experience.

Developing a measure of loneliness

Research on loneliness has been hindered by the lack of a simple and reliable assessment technique. The development of the UCLA Loneliness Scale, a short, 20-item general measure of loneliness is reported. The measure has high internal consistency (coefficient alpha = .96) and a test-retest correlation over a two-month period of .73. Concurrent and preliminary construct validity are indicated by correlations with self-reports of current loneliness and related emotional states, and by volunteering for a "loneliness clinic."

Functional recovery in parkinsonian monkeys treated with GDNF

Parkinson's disease results from the progressive degeneration of dopamine neurons that innervate the striatum. In rodents, glial-cell-line-derived neurotrophic factor (GDNF) stimulates an increase in midbrain dopamine levels, protects dopamine neurons from some neurotoxins, and maintains injured dopamine neurons. Here we extend the rodent studies to an animal closer to the human in brain organization and function, by evaluating the effects of GDNF injected intracerebrally in rhesus monkeys that have had the symptomatology and pathophysiological features of Parkinson's disease induced by the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). The recipients of GDNF displayed significant improvements in three of the cardinal symptoms of parkinsonism: bradykinesia, rigidity and postural instability. GDNF administered every four weeks maintained functional recovery. On the lesioned side of GDNF-treated animals, dopamine levels in the midbrain and globus pallidus were twice as high, and nigral dopamine neurons were, on average, 20% larger, with an increased fibre density. The results indicate that GDNF may be of benefit in the treatment of Parkinson's disease.

Bacterial resistance to silver in wound care

Ionic silver exhibits antimicrobial activity against a broad range of micro-organisms. As a consequence, silver is included in many commercially available healthcare products. The use of silver is increasing rapidly in the field of wound care, and a wide variety of silver-containing dressings are now commonplace (e.g. Hydrofiber dressing, polyurethane foams and gauzes). However, concerns associated with the overuse of silver and the consequent emergence of bacterial resistance are being raised. The current understanding of the biochemical and molecular basis behind silver resistance has been documented since 1998. Despite the sporadic evidence of bacterial resistance to silver, there have been very few studies undertaken and documented to ascertain its prevalence. The risks of antibacterial resistance developing from the use of biocides may well have been overstated. It is proposed that hygiene should be emphasized and targeted towards those applications that have demonstrable benefits in wound care. It is the purpose of this review to assess the likelihood of widespread resistance to silver and the potential for silver to induce cross-resistance to antibiotics, in light of its increasing usage within the healthcare setting.

The modulation of fluorouracil with leucovorin in metastatic colorectal carcinoma: a prospective randomized phase III trial. Gastrointestinal Tumor Study Group

A total of 343 patients with previously untreated metastatic measurable colorectal carcinoma were studied to evaluate the impact on toxicity, response, and survival of leucovorin-modulated fluorouracil (5-FU). A maximally tolerated intravenous bolus loading course regimen of 5-FU alone (500 mg/m2 x 5 days every 4 weeks with 25 mg/m2 escalation) was compared with a high-dose leucovorin regimen (600 mg/m2 of 5-FU with 500 mg/m2 of leucovorin weekly for 6 weeks with a 2-week rest) and with a similar low-dose leucovorin regimen (600 mg/m2 of 5-FU with 25 mg/m2 of leucovorin weekly for 6 weeks with a 2-week rest). The dose-limiting toxicity for the two 5-FU and leucovorin regimens was gastrointestinal, specifically diarrhea; severe diarrhea was seen frequently, and treatment-related toxicity was implicated in the demise of 11 of the patients (5%). Significant improvements in response rates were observed with a response rate of 33 of 109 (30.3%) on the high-dose leucovorin regimen (P less than .01 v control); 13 of 107 (12.1%) on the 5-FU control; and 21 of 112 (18.8%) on the low-dose leucovorin regimen. A trend toward longer survival in the 5-FU plus high-dose leucovorin regimen was observed. In this study, leucovorin was shown to significantly enhance the therapeutic effect of 5-FU in metastatic colorectal carcinoma.

Consensus on microembolus detection by TCD. International Consensus Group on Microembolus Detection

Transcranial Doppler ultrasound is capable of detecting microembolic material, both gaseous and solid, within the intracranial cerebral arteries. To avoid discrediting this promising and exciting new technique, experts in this field met in January 1997 in Frankfurt, Germany, to discuss the limitations and problems of embolus detection and to determine guidelines for its proper use in clinical practice, as well as in scientific investigations. In particular, the authors suggest that studies report the following parameters: (1) ultrasound device, (2) transducer type and size, (3) insonated artery, (4) insonation depth, (5) algorithms for signal intensity measurement, (6) scale settings, (7) detection threshold, (8) axial extension of sample volume, (9) fast Fourier transform (FFT) size (number of points used), (10) FFT length (time), (11) FFT overlap, (12) transmitted ultrasound frequency, (13) high-pass filter settings, and (14) recording time. There was agreement that no current system of automatic embolus detection has the required sensitivity and specificity for clinical use.

The psychometric properties of a tinnitus handicap questionnaire

The psychometric properties of a tinnitus handicap questionnaire are reported. There were two phases in this study. In Phase I, 87 questions were administered to 100 tinnitus patients. From their responses, 59 items that were either redundant, insensitive, or had low item-total correlations were eliminated. In Phase II, the resulting 27-item questionnaire was administered to 319 patients. Fifty-three of these patients also completed psychological and psychophysical measures that were used to validate the questionnaire. A factor analysis of patients' responses revealed a three-factor structure. These three factors appeared to reflect the physical, emotional, and social consequences of tinnitus (Factor 1), hearing ability of the patient (Factor 2), and the patients' view of tinnitus (Factor 3). Although the 27-item questionnaire had high internal consistency reliability and validity as reflected by correlations with life satisfaction and depression scales, it is recommended that only the items on the Factor 1 and the Factor 2 subscales be scored because of the low internal consistency reliability of the Factor 3 subscale. This questionnaire can be used to compare a patient's tinnitus handicap with the norm, identify specific areas of handicaps, and to monitor a patient's progress with particular treatment programs.

Systematic review: the prevalence of idiopathic bile acid malabsorption as diagnosed by SeHCAT scanning in patients with diarrhoea-predominant irritable bowel syndrome

BACKGROUND

Recurrent, watery diarrhoea affects one-third of patients diagnosed with irritable bowel syndrome ('IBS-D'). Idiopathic bile acid malabsorption ('I-BAM') may be the cause.

AIM

To determine the prevalence of I-BAM in patients suffering from IBS-D.

METHODS

A systematic search was performed of publications reporting patients presenting with IBS-D type symptoms, who were subsequently confirmed as having I-BAM by SeHCAT scanning.

RESULTS

Eighteen relevant studies, 15 prospective, comprising 1223 patients were identified. Five studies (429 patients) indicated that 10% (CI: 7-13) patients had severe bile acid malabsorption (SeHCAT 7 day retention <5% of baseline value). 17 studies (1073 patients) indicated that 32% (CI: 29-35) patients had moderate bile acid malabsorption (SeHCAT <10%). 7 studies (618 patients) indicated that 26% (CI: 23-30) patients had mild (SeHCAT <15%) bile acid malabsorption. Pooled data from 15 studies showed a dose-response relationship according to severity of malabsorption to treatment with a bile acid binder: response to colestyramine occurred in 96% of patients with <5% retention, 80% at <10% retention and 70% at <15% retention.

CONCLUSIONS

Idiopathic adult-onset bile acid malabsorption is not rare. International guidelines for the management of irritable bowel syndrome need to be revised so that clinicians become more aware of this possibility.

Social and emotional loneliness: an examination of Weiss's typology of loneliness

This study examined Weiss' conceptualization of social and emotional loneliness. Using data from an extensive survey of undergraduate and graduate students at the University of Iowa, we measured social and emotional loneliness, students' affective and behavioral reactions to loneliness, students' social relationships, and their judgments of the degree to which their relationships supply the six social provisions described by Weiss. As expected, we found differences in the subjective experiences of social and emotional loneliness, although both forms of loneliness were also characterized by a common core of experiences. The results generally supported Weiss's ideas concerning the determinants of social and emotional loneliness. Predictions concerning the affective and behavioral consequences associated with each type of loneliness, however, were only partly supported, although the two forms of loneliness were associated with different affective reactions and coping behaviors. The implications of these findings for Weiss's typology of loneliness are discussed.

Economic costs of the foot and mouth disease outbreak in the United Kingdom in 2001

The authors present estimates of the economic costs to agriculture and industries affected by tourism of the outbreak of foot and mouth disease (FMD) in the United Kingdom (UK) in 2001. The losses to agriculture and the food chain amount to about Pound Sterling3.1 billion. The majority of the costs to agriculture have been met by the Government through compensation for slaughter and disposal as well as clean-up costs. Nonetheless, agricultural producers will have suffered losses, estimated at Pound Sterling355 million, which represents about 20% of the estimated total income from farming in 2001. Based on data from surveys of tourism, businesses directly affected by tourist expenditure are estimated to have lost a similar total amount (between Pound Sterling2.7 and Pound Sterling3.2 billion) as a result of reduced numbers of people visiting the countryside. The industries which supply agriculture, the food industries and tourist-related businesses will also have suffered losses. However, the overall costs to the UK economy are substantially less than the sum of these components, as much of the expenditure by tourists was not lost, but merely displaced to other sectors of the economy. Overall, the net effect of FMD is estimated to have reduced the gross domestic product in the UK by less than 0.2% in 2001.

The targeting of Lamp1 to lysosomes is dependent on the spacing of its cytoplasmic tail tyrosine sorting motif relative to the membrane

Lamp1 is a type I transmembrane glycoprotein that is localized primarily in lysosomes and late endosomes. Newly synthesized molecules are mostly transported from the trans-Golgi network directly to endosomes and then to lysosomes. A minor pathway involves transport via the plasma membrane. The 11-amino acid cytoplasmic tail of lamp1 contains a tyrosine-based motif that has been previously shown to mediate sorting in the trans-Golgi network and rapid internalization at the plasma membrane. We studied whether this motif also mediates sorting in endosomes. We found that mutant forms of lamp1 in which all the amino acids of the cytoplasmic tail were modified except for the RKR membrane anchor and the YXXI sorting motif still localized to dense lysosomes, indicating that the YXXI motif is sufficient to confer proper intracellular targeting. However, when the spacing of the YXXI motif relative to the membrane was changed by deleting one amino acid or adding five amino acids, lysosomal targeting was almost completely abolished. Kinetic studies showed that these mutants were trapped in a recycling pathway, involving trafficking between the plasma membrane and early endocytic compartments. These findings indicate that the YXXI signal of lamp1 is recognized at several sorting sites, including the trans-Golgi network, the plasma membrane, and the early/sorting endosomes. Small changes in the spacing of this motif relative to the membrane dramatically impair sorting in the early/sorting endosomes but have only a modest effect on internalization at the plasma membrane. The spacing of sorting signals relative to the membrane may prove to be an important determinant in the functioning of these signals.

Risk factors related to carotid intima-media thickness and plaque in children with familial hypercholesterolemia and control subjects

To assess the relationship between risk factors for cardiovascular disease and early atherosclerotic changes in the carotid artery, we measured carotid intima-media thickness by B-mode ultrasonography in 61 boys and 29 girls 10 to 19 years old with familial hypercholesterolemia (FH) and 30 control subjects matched for age and sex. All were nonsmokers, and all the FH adolescents had a known mutation in the LDL receptor gene. Mean intima-media thickness in the far wall of the carotid bulb was greater (P = .03) in the FH group than in the control subjects: 0.54 mm (95% confidence interval [CI], 0.52 to 0.56) versus 0.50 mm (95% CI, 0.47 to 0.52). In the entire group, mean and maximum intima-media thicknesses in the carotid bulb were positively associated with levels of apolipoprotein B and fibrinogen after control for pubertal stage (r = .19 to .24; P < .05), as was male sex. Plasma total homocysteine was similar in the FH and control groups and was associated with mean and maximum intima-media thicknesses in the far wall of the common carotid artery and carotid bulb after control for pubertal stage (r = .22 to .28; P < .05). With the exception of the relation between plasma fibrinogen level and mean carotid bulb intima-media thickness, these associations were essentially unchanged in stepwise multiple linear regression analyses, allowing for the entry of BMI and level of HDL cholesterol into the analysis. Carotid artery plaque was present in 10% of the children with FH versus none of the control subjects. Children with plaque had a higher mean cholesterol-years score than children without plaque. These findings suggest that the classic lipid and hemostatic risk factors as well as plasma total homocysteine are associated with markers of early carotid atherosclerosis from the second decade of life. B-mode ultrasonography may prove to be a useful tool in risk stratification of children with FH.

MEK kinase 1 gene disruption alters cell migration and c-Jun NH2-terminal kinase regulation but does not cause a measurable defect in NF-kappa B activation

MEK kinase 1 (MEKK1) is a 196-kDa mitogen-activated protein kinase (MAPK) kinase kinase that, in addition to regulating the c-Jun NH(2)-terminal kinase (JNK) pathway, is involved in the control of cell motility. MEKK1(-/-) mice are defective in eyelid closure, a TGFalpha-directed process involving the migration of epithelial cells. MEKK1 expression in epithelial cells stimulates lamellipodia formation, a process required for cell movement. In addition, mouse embryo fibroblasts derived from MEKK1(-/-) mice are inhibited in their migration relative to MEKK1(+/+) fibroblasts. MEKK1 is required for JNK but not NF-kappaB activation in response to virus infection, microtubule disruption, and stimulation of embryonic stem cells with lysophosphatidic acid. MEKK1 is not required for TNFalpha or IL-1 regulation of JNK or NF-kappaB activation in macrophages or fibroblasts. Thus, MEKK1 senses microtubule integrity, contributes to the regulation of fibroblast and epithelial cell migration, and is required for activation of JNK but not NF-kappaB in response to selected stress stimuli.

A randomized, prospective multicenter pharmacoepidemiologic study of cyclosporine microemulsion in stable renal graft recipients. Report of the Canadian Neoral Renal Transplantation Study Group

BACKGROUND

The safety, tolerability, and pharmacokinetics of conventional cyclosporine (ConCsA) and cyclosporine microemulsion (MeCsA) were compared under conditions of normal clinical practice in a prospective, randomized, concentration-controlled, pharmacoepidemiologic study.

METHODS

Between September 1994 and March 1995, 1097 stable renal transplant recipients in 14 Canadian centers were randomized 2:1 to treatment with MeCsA or ConCsA. Patients were commenced on each study drug at a dose equal to their previous therapy with ConCsA, and the dose was adjusted to maintain predose whole blood cyclosporine concentrations within the therapeutic range established for each center. Prednisone and azathioprine were continued unless dose adjustment was required for clinical reasons.

RESULTS

The mean cyclosporine concentration was comparable in both treatment groups at all time points throughout the 6 months of follow-up. The mean dose of cyclosporine was 3.6 mg/kg/day in both treatment groups at entry to the study, and declined by 0.3% and by 2.8% in patients receiving ConCsA and MeCsA, respectively. The nature and severity of adverse events were similar in both treatment groups, but there was a transient increase in neurological and gastrointestinal complications in the group receiving MeCsA within the first month after conversion (P<0.05). Serum creatinine and creatinine clearance did not change in either treatment group throughout the study. Biopsy-proven acute rejection occurred in three patients (0.8%) receiving ConCsA and in seven patients (0.9%) receiving MeCsA, with non-histologically proven acute rejection in an additional three patients (0.8%) receiving ConCsA and five patients (0.6%) receiving MeCsA (P=NS). Serum creatinine rose transiently in 35 patients (9.8%) receiving ConCsA and 138 patients (18.7%) receiving MeCsA (P<0.05) and resolved either spontaneously or after a reduction in the cyclosporine dose. One graft was lost in the MeCsA group due to irreversible rejection, and seven patients died, three in the group receiving ConCsA and four of those receiving MeCsA (P=NS). Absorption of cyclosporine was more rapid and complete from MeCsA than from ConCsA during the first 4 hr of the dosing interval, resulting in almost 40% greater exposure to the drug (P<0.001). There was close correlation between area under the time-concentration curve (AUC) over the first 4 hr of the 12-hr dosage interval and AUC over the entire 12-hr dosage interval for both formulations, making AUC over the first 4 hr a good predictor of total cyclosporine exposure. Using this parameter, patients with low absorption randomized to receive MeCsA showed a marked increase in drug exposure by months 3 and 6, whereas there was no change in those who continued on ConCsA. A limited sampling strategy utilizing samples at the predose and postdose trough levels provided an excellent correlation with drug exposure, particularly for patients receiving MeCsA (r2=0.94 MeCsA vs. r2=0.89 ConCsA).

CONCLUSIONS

MeCsA appears to be a safe and effective therapy in stable renal transplant patients and provides superior and more consistent absorption of cyclosporine when compared with ConCsA. Transient toxicity after conversion to MeCsA occurs in some patients, and may reflect the increased exposure to cyclosporine. Use of a limited sampling approach combining trough and 2-hr postdose concentrations may provide an effective way to monitor this exposure.

Long-term effects of incestuous abuse in childhood

The authors studied two groups of adult women with histories of incest, a nonclinical sample (N = 152) and an outpatient sample (N = 53). Women in the community sample reported a range of long-term effects from the incest. The great majority said they had been upset by their incest experiences, but about half said they had recovered well from their trauma. Most women who had suffered forceful, prolonged, or highly intrusive sexual abuse, or who had been abused by their father or stepfather, reported long-lasting negative effects. The patient sample reported histories comparable to the most severe traumatic histories in the community sample.

Pulsed Doppler echocardiographic study of left ventricular filling in dilated cardiomyopathy

Patients with dilated cardiomyopathy (DC) have been reported to have abnormal left ventricular (LV) diastolic properties. To evaluate LV diastolic filling characteristics in patients with DC, pulsed Doppler echocardiography was used to study mitral flow velocity in 21 patients with DC and mitral regurgitation (MR), 12 patients with DC but no MR and 19 age-matched normal subjects. Diagnosis of MR was based on the Doppler echocardiographic finding of holosystolic turbulent flow in the left atrium. Peak mitral flow velocity in early diastole (PFVE) and during atrial systole (PFVA), PFVA/PFVE and deceleration half-time of early diastolic flow were measured from Doppler mitral flow velocity recordings. In 21 patients with DC and MR, PFVE (61 +/- 13 cm/s), PFVA (37 +/- 19 cm/s) and PFVA/PFVE (0.6 +/- 0.4) were not significantly different from PFVE (53 +/- 10 cm/s), PFVA (47 +/- 12 cm/s) and PFVA/PFVE (1.0 +/- 0.4) in normal subjects (p greater than 0.05). Deceleration half-time in DC patients with MR (62 +/- 32 ms) was shorter than normal (87 +/- 25 ms) (p less than 0.05). In contrast, PFVE (31 +/- 11 cm/s) was lower and PFVA/PFVE (1.7 +/- 0.8) was higher in the 12 DC patients without MR than in normal subjects and DC patients with MR (p less than 0.005). PFVA (46 +/- 8 cm/s) and deceleration half-time (88 +/- 33 ms) in patients without MR were not significantly different from normal mean values. Thus, abnormalities of peak diastolic mitral flow velocity were detected in DC patients without MR but not in DC patients with MR, suggesting that MR masks LV filling abnormalities in patients with DC.

Social support and adaptation to stress by the elderly

The first of a two-phase project is reported that examined the prospective effects of stress and social support on the physical and mental health of the elderly. A sample of 50 elderly subjects was assessed at two points in time over a 6-month period. Results indicated that social support was a significant predictor of physical health status, whereas mental health was related to the Stress X Social Support interaction term. These latter results were consistent with the buffering hypothesis, in that high levels of social support served to reduce the negative impact of stress on mental health. Individuals who were in better mental health at the initial assessment experienced fewer stressful events and higher levels of social support over the subsequent 6-month period. The implications of these findings for research and theory regarding the relation between stress and social support are discussed.

Effect of nitroglycerin on cerebral circulation measured by transcranial Doppler and SPECT

We used a combination of transcranial Doppler ultrasonography and single-photon emission computed tomography to noninvasively assess changes in the diameter of the middle cerebral artery induced by sublingual nitroglycerin in 10 healthy subjects. Nitroglycerin reduced mean blood flow velocities without concurrently changing regional cerebral blood flow in the perfusion territory of this vessel. Our results strongly suggest that nitroglycerin causes vasodilatation of the basal intracranial arteries.

Left ventricular filling in hypertrophic cardiomyopathy: a pulsed Doppler echocardiographic study

Abnormal left ventricular diastolic properties have been described in patients with hypertrophic cardiomyopathy. To evaluate the diastolic filling characteristics of the left ventricle in patients with this disease, pulsed Doppler echocardiography was used to study mitral flow velocity in 17 patients with hypertrophic cardiomyopathy (11 with and 6 without systolic anterior motion of the mitral valve) and 16 age-matched normal subjects. There were no statistically significant differences between patients with hypertrophic cardiomyopathy with and without systolic anterior motion with regard to ventricular septal thickness, left ventricular posterior wall thickness, left ventricular internal dimensions or the extent of hypertrophy evaluated by two-dimensional echocardiography. Mitral regurgitation was detected by Doppler echocardiography in all 11 patients with and in 2 (33%) of the 6 patients without systolic anterior motion of the mitral valve. Early and late diastolic peak flow velocity, the ratio of late to early diastolic peak flow velocity and deceleration of early diastolic flow were measured from Doppler mitral flow velocity recordings. There were no statistically significant differences in these four indexes between the patients with systolic anterior motion and normal subjects. In contrast, the patients with hypertrophic cardiomyopathy without systolic anterior motion showed lower early diastolic peak flow velocity, higher ratio of late to early diastolic peak flow velocity and lower deceleration of early diastolic flow compared with the patients with systolic anterior motion and normal subjects, suggesting impaired left ventricular diastolic filling.(ABSTRACT TRUNCATED AT 250 WORDS)

The revised UCLA Loneliness Scale: concurrent and discriminant validity evidence

The development of an adequate assessment instrument is a necessary prerequisite for social psychological research on loneliness. Two studies provide methodological refinement in the measurement of loneliness. Study 1 presents a revised version of the self-report UCLA (University of California, Los Angeles) Loneliness Scale, designed to counter the possible effects of response bias in the original scale, and reports concurrent validity evidence for the revised measure. Study 2 demonstrates that although loneliness is correlated with measures of negative affect, social risk taking, and affiliative tendencies, it is nonetheless a distinct psychological experience.

Detection of arterial emboli using Doppler ultrasound in rabbits

The purpose of this study was to develop an animal model that could be used to test the ability of Doppler ultrasound to detect arterial emboli composed of materials that are often involved in cerebral emboli. Emboli introduced into the rabbit aorta via the left renal artery consisted of clotted whole blood, platelets, atheromatous material, fat, or air. The ultrasound examination was carried out continuously during the studies using a multifrequency transcranial Doppler apparatus with a 2-MHz probe, a sample volume of 15 mm, at a depth of 15 mm. The intensity of the Doppler spectrum was measured and displayed as a 15-shade color scale, each shade representing a 3-dB difference. The diameter of the aorta at the site of the ultrasound examination was similar to the diameter of the middle cerebral artery in humans. All 125 emboli introduced were clearly detected because they caused a Doppler signal at least 15 dB greater than that of the surrounding blood. These results show that the potential for emboli detection using Doppler ultrasound in the clinical situation is now considerable.

Akt-induced endocrine therapy resistance is reversed by inhibition of mTOR signaling

BACKGROUND

Resistance to endocrine therapy is a major impediment in breast cancer therapeutics. The Phosphatidylinositol-3-OH kinase (PI3K)/Protein kinase B (Akt/PKB) kinase signaling pathway has been implicated in altering breast cancer response to multiple therapies. How Akt modulates response is an area of significant clinical relevance.

METHODS

We have used an in vitro model to discern the effects of robust Akt activity on breast cancer cellular response to endocrine therapies.

RESULTS

High levels of Akt activity confer resistance to the aromatase inhibitor Letrozole (Let) and the selective estrogen receptor (ER) down-regulator Fulvestrant (ICI). Akt-induced resistance is not due to failure of these endocrine agents to inhibit estrogen receptor alpha activity. Instead, resistance is characterized by altered cell cycle and apoptotic response. Cotreatment with low concentrations of the mTOR inhibitor RAD-001 and either Let or ICI restores response of the resistant cells to levels observed in the responsive cells treated with either Let or ICI as a single agent.

CONCLUSIONS

Our preliminary findings in experiments with RAD-001 indicate that cotreatment with mTOR inhibitors and either Let or ICI reverses the Akt-mediated resistance and restores responsiveness to antiestrogens. Concurrent ER and mTOR inhibition is therefore an effective strategy to overcome growth factor-induced resistance and bears significant implications for optimal clinical development of these agents in breast cancer treatment.