New measurement of the K+-->pi+ nunu branching ratio

Three events for the decay K+-->pi+ nunu have been observed in the pion momentum region below the K+-->pi+pi0 peak, 140 < Ppi < 199 MeV/c, with an estimated background of 0.93+/-0.17(stat.) -0.24+0.32(syst.) events. Combining this observation with previously reported results yields a branching ratio of B(K+-->pi+ nunu) = (1.73(-1.05)+1.15) x 10(-10) consistent with the standard model prediction.

School climate and teachers' beliefs and attitudes associated with implementation of the positive action program: a diffusion of innovations model

Teacher- and school-level factors influence the fidelity of implementation of school-based prevention and social character and development (SACD) programs. Using a diffusion of innovations framework, the relationships among teacher beliefs and attitudes towards a prevention/SACD program and the influence of a school's administrative support and perceptions of school connectedness, characteristics of a school's climate, were specified in two cross-sectional mediation models of program implementation. Implementation was defined as the amount of the programs' curriculum delivered (e.g., lessons taught), and use of program-specific materials in the classroom (e.g., ICU boxes and notes) and in relation to school-wide activities (e.g., participation in assemblies). Teachers from 10 elementary schools completed year-end process evaluation reports for year 2 (N = 171) and 3 (N = 191) of a multi-year trial. Classroom and school-wide material usage were each favorably associated with the amount of the curriculum delivered, which were associated with teachers' attitudes toward the program which, in turn, were related to teachers' beliefs about SACD. These, in turn, were associated with teachers' perceptions of school climate. Perceptions of school climate were indirectly related to classroom material usage and both indirectly and directly related to the use of school-wide activities. Program developers need to consider the importance of a supportive environment on program implementation and attempt to incorporate models of successful school leadership and collaboration among teachers that foster a climate promoting cohesiveness, shared visions, and support.

Did the pattern of practice in the prescription of palliative radiotherapy for the treatment of uncomplicated bone metastases change between 1999 and 2005 at the rapid response radiotherapy program?

AIMS

Since 1999, randomised clinical trials and meta-analyses have reported equal efficacy of pain relief from single- and multiple-fraction radiotherapy for bone metastases. A number of factors, including limited radiotherapy resources, waiting times, and patient convenience, suggest single fraction to be the treatment of choice for patients. However, international patterns of practice indicate that multiple fractions are still commonly used. This study examined whether dose-fractionation schemes used for the treatment of bone metastases at the Rapid Response Radiotherapy Program (RRRP) at the Odette Cancer Centre have changed since 1999.

MATERIALS AND METHODS

A retrospective review of the prospective RRRP database and hospital records were conducted for all patients treated with palliative radiotherapy for uncomplicated bone metastases at the RRRP in 1999 (or baseline), 2001, 2004 and from 1 January to 31 July 2005. Data were collected on patient demographics and clinical characteristics.

RESULTS

Of the 693 patients, 65 and 35% were prescribed single fraction (predominantly single 8 Gy) and multiple fractions (predominantly 20 Gy/five fractions), respectively. The administration of single treatments generally increased over time, from 51% in 1999 to 66% in 2005 (P=0.0001). On the basis of multiple logistic regression analyses, patients were more likely to be prescribed single-fraction radiotherapy if they had prostate cancer, had a poorer performance status, were treated to the limbs, hips, shoulders, pelvis, ribs, scapula, sternum, or clavicle (compared with the spine), were treated by a radiation oncologist who had been trained in earlier years, and who were treated after 1999.

CONCLUSIONS

Between 1999 and 2005, the use of single-fraction radiotherapy increased, corresponding to publications showing equal efficacy of pain relief between single and multiple fractions in the management of uncomplicated bone metastases. However, about a third of patients still received multiple fractions.

Goal conflict and the moderating effects of intention stability in intention-behavior relations: physical activity among Hong Kong chinese

This study examined how goal conflict influences the pattern of the moderating effects of intention stability on the intention-behavior relations in the context of physical activity participation. A longitudinal study of 136 young adult students with three waves of data collection (a 2-week interval between waves) was conducted. Results showed a significant three-way interaction among intention, goal conflict,& intention stability in explaining vigorous-intensity physical activity (Beta = -.25, p < .05). Consistent with our expectation, the pattern of the three-way interaction revealed that when the level of goal conflict was low, the intention-behavior relations were stronger with stable intentions and weaker with unstable intentions. However, when the level of goal conflict was high, the intention-behavior relations were weaker with stable intentions and stronger with unstable intentions. Possible underlying processes of goal conflict and intention stability on the intention-behavior relations are discussed.

Glutamate-induced retinal lipid and protein damage: the protective effects of catechin

Glutamate toxicity has been implicated in various retinal diseases. Green tea leaf extract catechin has protective effects against cellular toxicity. This study investigated the effects of catechin on the glutamate-treated retina. Porcine retinal homogenates were incubated with glutamate (20 nmol) at 37 degrees C for 60 min. Catechin was co-incubated with the glutamate-treated retina in the same condition. The malondialdehyde (MDA) levels were determined as an index of lipid peroxidation (LPO). Differential protein expressions were derived from two-dimensional gel electrophoresis. Mass spectrometry was conducted to identify the proteins. Glutamate increased the retinal MDA (p<0.0001) and catechin reversed the effect (p<0.0001). There were significant changes in seven proteins after the glutamate treatment (p<0.05), namely, heterogeneous ribonucleoprotein, thioredoxin peroxidase, 5-hydroxytryptamine receptor, pyruvate dehydrogenase, ARHA protein, peroxiredoxin 6 and proteasome. Catechin significantly reversed the changes in thioredoxin peroxidase, 5-hydroxytryptamine receptor, peroxiredoxin 6 and pyruvate dehydrogenase (p<0.05). Our study shows that (a) retinal glutamate toxicity is mediated by LPO and protein modification, and (b) catechin ameliorates the toxicity.

The epidemiology and clinical characteristics of Crohn's disease in the Hong Kong Chinese population: experiences from a regional hospital

OBJECTIVE

To study the descriptive epidemiology and clinical profile of patients with Crohn's disease.

DESIGN

Retrospective study.

SETTING

Regional hospital, Hong Kong.

PATIENTS

Patients with Crohn's disease diagnosed between January 1991 and December 2006 inclusive.

RESULTS

Over the period studied, 27 Chinese patients were diagnosed with Crohn's disease in our hospital. Our hospital-based incidence and prevalence rate had increased more than 2- and 5-fold, respectively over that period. The mean age at diagnosis was 26 years and median duration of disease was 81 months. Most patients had ileocolonic disease (67%) followed by Crohn's colitis (22%) and ileal disease (11%); more patients had non-stricturing and non-penetrating disease (63%) than stricturing (15%) or penetrating disease (22%). Peri-anal disease occurred in 37% of our patients. At diagnosis, many of the patients (41%) had mild-moderate disease, but 30% each had moderate-severe and severe-fulminant disease. At the time of this study, 85% of the patients were in disease remission with medical treatment. However, 48% had undergone surgery for diagnosis or complications. No patient had developed colorectal cancer or died.

CONCLUSIONS

The incidence and prevalence of Crohn's disease are increasing in the Chinese population. It usually affects young persons with a substantial proportion of patients presented with severe-fulminant disease. More epidemiological and clinical studies are needed for this emerging disease in Asian regions.

Improved measurement of the K+-->pi+nunu; branching ratio

An additional event near the upper kinematic limit for K+-->pi(+)nunu; has been observed by experiment E949 at Brookhaven National Laboratory. Combining previously reported and new data, the branching ratio is B(K+-->pi(+)nunu;)=(1.47(+1.30)(-0.89))x10(-10) based on three events observed in the pion momentum region 211<P<229 MeV/c. At the measured central value of the branching ratio, the additional event had a signal-to-background ratio of 0.9.

Case selection in macular relocation surgery for age related macular degeneration

BACKGROUND

To date there has been no randomised controlled trial demonstrating the safety and efficacy of macular relocation surgery (MRS) for age related macular degeneration (AMD). Vision can be improved in some patients and made worse in others despite successful surgery or because of complications.

PURPOSE

To determine which patients would benefit from MRS.

METHODS

Twenty nine patients with exudative AMD took part in a prospective, non-comparative, interventional study. Macular relocation surgery involved phacoemulsification, vitrectomy, 360 degrees retinotomy, excision of choroidal neovascular membrane, and macular relocation using an infusion of 5-fluorouracil and low molecular weight heparin as adjuvant to prevent proliferative vitreoretinopathy. Patients underwent protocol refraction preoperatively and six-monthly postoperatively by designated optometrists. Preoperative fundus fluorescein angiograms were read by masked observers and the lesions were classified according to a set protocol. The main outcome measures were visual improvement, final vision of better than 20/400, reading speed, critical print size. Logistic and multiple stepwise linear regressions were used to identify independent factors which predicted the main outcomes.

RESULTS

Preoperative visual acuity (20/120 or worse) and lesion type (predominantly classic or submacular haemorrhage) were significantly associated with visual improvement (coefficient of regression B = 26.8, p<0.001 and B = 14.9 with p = 0.045 respectively). There were no significant independent factors which predicted a final distance logMAR visual acuity of 1.3 (20/400) or any arbitrary definition of blindness.

CONCLUSIONS

The study showed that it was possible to select cases that were more likely to experience an improvement in vision following MRS.

Further evidence for the decay K+ -->pi+nu(nu)

Additional evidence for the rare kaon decay K+-->pi+nu(nu) has been found in a new data set with comparable sensitivity to the previously reported result. One new event was observed in the pion momentum region examined, 211<P<229 MeV/c, bringing the total for the combined data set to two. Including all data taken, the backgrounds were estimated to contribute 0.15+/-0.05 events. The branching ratio is B(K+-->pi+nu(nu)) = 1.57(+1.75)(-0.82)x10(-10).

Obstructive sleep apnea surgery: genioglossus advancement revisited

PURPOSE

This study evaluated the accuracy of a genioglossus advancement (GA) technique (rectangular window) to incorporate the genial tubercle/genioglossus muscle complex (GGC) in patients with obstructive sleep apnea.

METHODS

This prospective study consisted of 38 consecutive patients who underwent GA. Preoperative localization of the GGC was based on the cephalometric and panoramic radiographs, as well as digital palpation in the floor of mouth. Immediately after completion of the osteotomy, the presence of the genial tubercles and the amount of the genioglossus muscle captured in the bone flap were examined directly.

RESULTS

All 38 pairs of genial tubercles were captured. Thirty-one patients had both bellies of the genioglossus muscle incorporated. Two patients had a complete belly and a partial (>50%) belly of the muscle captured. Five patients had only a portion (>50%) of both muscle bellies included. The incomplete incorporation of the muscles in the bone flap was caused by the limited lateral extension of the osteotomy beyond the genial tubercles. The causes of the limited lateral osteotomy extension included crowding of the lower incisors as well as the presence of elongated and/or medially angulated canine roots.

CONCLUSION

The results of this study show that the rectangular osteotomy technique accurately captures the genial tubercles and enables an adequate amount of the genioglossus muscle to be incorporated and advanced. However, limited lateral extension of the osteotomy can result in a decreased incorporation of genioglossus muscle in some patients.

Uvulopalatopharyngoplasty, maxillomandibular advancement, and the velopharynx

OBJECTIVE

To evaluate the presence of velopharyngeal insufficiency (VPI) symptoms and the associated changes of the velopharyngeal anatomy in patients who underwent maxillomandibular advancement (MMA) for persistent obstructive sleep apnea (OSA) after uvulopalatopharyngoplasty (UPPP).

METHODS

Preoperative and postoperative cephalometric radiographs were analyzed to assess the anatomic changes of the velopharynx. In addition, a questionnaire survey was sent to the patients between 6 to 12 months after MMA. The questionnaires evaluated the presence and extent of VPI symptoms, including nasal regurgitation while eating or drinking as well as hypernasal speech. A 10-cm visual analog scale (VAS 0-10) was included to assess the impact of VPI symptoms on the patient's quality of life. In the patients who reported VPI symptoms, telephone interviews were conducted 1 year after the survey to evaluate the changes in VPI symptoms over time.

RESULTS

Fifty-two of the 65 questionnaires were returned. Five patients (9.6%) reported nasal regurgitation of liquids when drinking hastily, with 2 patients reporting the occurrences as occasional and 3 patients reporting as rare. The impact of these symptoms on the patient's quality of life was minimal (VAS 0.6 +/- 0.4). Regurgitation of food or hypernasal speech was not reported. The telephone interviews 1 year later revealed that the symptoms have completely resolved in all 5 patients. Comparison of the preoperative and postoperative cephalometric radiographs demonstrated the pharyngeal depth increase was 48% of the amount of maxillary advancement and the functional pharyngeal length increased 53% of the maxillary advancement. The functional depth of the pharynx after MMA was significantly greater in the patients with VPI symptoms (P=.01).

CONCLUSION

The results of this study suggest that patients who undergo MMA for persistent OSA after UPPP have a low risk of developing VPI. If symptoms occur postoperatively, they are mild and have minimal effect on the patient's quality of life; moreover, the symptoms usually resolve over time.

Patient's perception of the facial appearance after maxillomandibular advancement for obstructive sleep apnea syndrome

PURPOSE

The goal of this study was to evaluate the patient's perception of the facial appearance after maxillomandibular advancement (MMA) surgery for obstructive sleep apnea syndrome (OSAS).

PATIENTS AND METHODS

During a 14-month period, 58 patients underwent MMA for OSAS. All of the patients underwent preoperative and postoperative cephalometric analysis. Between 6 and 12 months after surgery, a questionnaire was mailed to each patient. The questionnaire asked the patient to evaluate subjectively their postoperative facial appearance. Visual analog scale ([VAS] 0 to 10) was used to assess the extent of the facial changes.

RESULTS

Forty-four (76%) patients (39 men, 6 women) responded to the questionnaire. Cephalometric analysis revealed that 40 patients had maxillomandibular protrusion postoperatively. Forty-two (96%) of the 44 patients reported changes in their facial appearance (VAS, 4.8 +/- 2.5). Twenty-four (55%) patients reported favorable facial changes (ie, they were more attractive [15 patients] and/or more youthful). Fourteen patients gave neutral responses (ie, they were no more or no less attractive). Four patients gave unfavorable responses (ie, they were less attractive after surgery).

CONCLUSION

The results suggest that most patients who underwent MMA for OSAS noted moderate changes in their facial appearance. Despite significant maxillomandibular protrusion based on the postoperative cephalometric analysis, more than 90% of the patients gave either positive or neutral responses to the changes in their facial appearance.

Risk factors for sleep bruxism in the general population

OBJECTIVE

Sleep bruxism can have a significant effect on the patient's quality of life. It may also be associated with a number of disorders. However, little is known about the epidemiology of sleep bruxism and its risk factors in the general population.

DESIGN

Cross-sectional telephone survey using the Sleep-EVAL knowledge based system.

SETTINGS

Representative samples of three general populations (United Kingdom, Germany, and Italy) consisting of 158 million inhabitants.

PARTICIPANTS

Thirteen thousand fifty-seven subjects aged > or = 15 years (United Kingdom, 4,972 subjects; Germany, 4,115 subjects; and Italy, 3,970 subjects).

INTERVENTION

None.

MEASUREMENTS

Clinical questionnaire on bruxism (using the International Classification of Sleep Disorders [ICSD] minimal set of criteria) with an investigation of associated pathologies (ie, sleep, breathing disorders, and psychiatric and neurologic pathologies).

RESULTS

Grinding of teeth during sleep occurring at least weekly was reported by 8.2% of the subjects, and significant consequences from teeth grinding during sleep (ie, muscular discomfort on awakening, disturbing tooth grinding, or necessity of dental work) were found in half of these subjects. Moreover, 4.4% of the population fulfilled the criteria of ICSD sleep bruxism diagnosis. Finally, subjects with obstructive sleep apnea syndrome (odds ratio [OR], 1.8), loud snorers (OR, 1.4), subjects with moderate daytime sleepiness (OR, 1.3), heavy alcohol drinkers (OR, 1.8), caffeine drinkers (OR, 1.4), smokers (OR, 1.3), subjects with a highly stressful life (OR, 1.3), and those with anxiety (OR, 1.3) are at higher risk of reporting sleep bruxism.

CONCLUSIONS

Sleep bruxism is common in the general population and represents the third most frequent parasomnia. It has numerous consequences, which are not limited to dental or muscular problems. Among the associated risk factors, patients with anxiety and sleep-disordered breathing have a higher number of risk factors for sleep bruxism, and this must raise concerns about the future of these individuals. An educational effort to raise the awareness of dentists and physicians about this pathology is necessary.

Measurement of direct photon emission in K+-->pi(+)pi(0)gamma decay

We have performed a measurement of the K+-->pi(+)pi(0)gamma decay and have observed 2x10(4) events. The best fit to the decay spectrum gives a branching ratio for direct photon emission of (4.7+/-0.8+/-0. 3)x10(-6) in the pi(+) kinetic energy region of 55 to 90 MeV and requires no component due to interference with inner bremsstrahlung.

Fiberoptic nasopharyngolaryngoscopy for airway monitoring after obstructive sleep apnea surgery

PURPOSE

This study evaluated the upper airway characteristics in the early postoperative period after reconstructive surgery for obstructive sleep apnea (OSA).

METHODS

During a 24-month period, the upper airway of patients who underwent uvulopalatopharyngoplasty (UPPP) with genioglossus advancement (GA) or hyoid myotomy (HM) or maxillomandibular advancement (MMA) were evaluated with fiberoptic nasopharyngolaryngoscopy (NPG) preoperatively and 24 to 72 hours postoperatively.

RESULTS

NPG was performed on 271 patients. One hundred seventy-three patients had UPPP with GA or HM, and the remainder had MMA. All of the patients who underwent UPPP with GA or HM were found to have varying degrees of soft tissue edema involving the soft palate and the tongue base. The patients who underwent tonsillectomies and UPPP with GA or HM had greater soft palate/pharyngeal wall edema. In contrast, patients who underwent MMA had minimal edema involving the soft palate and the base of tongue, but diffuse lateral pharyngeal wall edema throughout the upper airway was identified. Eighteen of the MMA patients had ecchymosis and edema involving the pyriform sinus and aryepiglottic fold; 4 of these patients also had a hypopharyngeal hematoma involving the pyriform sinus, aryepiglottic fold, arytenoid, and false vocal cord, which partially obstructed the airway. These 4 patients were closely monitored for 1 to 2 additional days, and all were discharged without problems. None of the patients in the study had postoperative airway obstruction.

CONCLUSION

NPG may be useful in postoperative airway monitoring and assist in discharge planning after upper airway reconstruction in the OSA patients.

Obstructive sleep apnea surgery: patient perspective and polysomnographic results

OBJECTIVE

The goal of this study was to assess the outcomes of obstructive sleep apnea (OSA) surgery based on the patient perspective and polysomnographic data.

STUDY DESIGN

Fifty-six patients with severe OSA completed the 2-phase reconstructive protocol. A minimum of 6 months after the phase II surgery and after the postoperative polysomnography, questionnaires with visual analog scales (VAS 0-10) were mailed to the patients to assess their perceptions of treatment results.

RESULTS

Forty-two (75%) questionnaires were returned. The mean patient age was 46.3 years. The mean respiratory disturbance index improved from 58.7 to 10.0. The mean lowest oxygen saturation improved from 76.3 to 87.3%. All 42 patients reported improved sleep (VAS 8.7). Although 10 patients reported changes in speech, the changes were insignificant, with 9 of the patients scoring 0 on the VAS (VAS 0.08 +/-0.3). Five patients reported changes in swallowing, and their VAS scores were 0.5, 0.9, 1.0, 2.7, and 6.9 (mean VAS 2.4+/-2.7). Forty patients (95%) were satisfied with their results and would undergo the reconstruction again.

CONCLUSION

Surgical airway reconstruction for severe OSA is a highly effective treatment option base on the objective as well as the subjective assessment.

Acanthamoeba rhinosinusitis: characterization, diagnosis, and treatment

Nasal and paranasal sinus manifestations are among the most common presentations of the acquired immunodeficiency syndrome (AIDS). Several studies cite that as many as 70% of patients with this disease have symptoms referable to the head and neck, including a 30% prevalence of sinusitis. Although the bacteriology of sinusitis in this population is largely considered comparable to that of immunocompetent patients, several opportunistic pathogens have been identified, particularly when T-cell counts are low. This report identifies Acanthamoeba as a potentially fatal cause of rhinosinusitis in immunosuppressed patients. The pathogenesis, diagnosis, and treatment of this rare entity will be discussed and the literature reviewed.

Obstructive sleep apnea syndrome: a comparison between Far-East Asian and white men

OBJECTIVES

To investigate the possible differences between Far-East Asian men and white men in obstructive sleep apnea syndrome (OSAS).

STUDY DESIGN

Prospective nonrandomized controlled study.

METHODS

This study compared consecutive Far-East Asian men with OSAS (n = 50) with two selected groups of White men with OSAS (n = 50 in each group). One group of white men was controlled for age, respiratory disturbance index (RDI), and minimum oxygenation saturation (LSAT). Another group was controlled for age and body mass index (BMI). Cephalometric analysis was performed on all subjects.

RESULTS

The majority of the Far-East Asian men were found to be nonobese (mean BMI, 26.7 +/- 3.8) but had severe OSAS (mean RDI, 55.1 +/- 35.1). When controlled for age, RDI, and LSAT, the white men were substantially more obese (mean BMI, 29.7 +/- 5.8, P = .0055). When controlled for age and BMI, the white men had less severe illness (RDI, 34.1 +/- 17.9, P = .0001). Although the posterior airway space and the distance from the mandibular plane to hyoid bone were less abnormal in the Far-East Asian men, the cranial base dimensions were significantly decreased.

CONCLUSIONS

The majority of the Far-East Asian men in this study were found to be nonobese, despite the presence of severe OSAS. When compared with white men, Far-East Asian men were less obese but had greater severity of OSAS. There may be differences in obesity and craniofacial anatomy as risk factors in these two groups.

Maxillomandibular advancement for persistent obstructive sleep apnea after phase I surgery in patients without maxillomandibular deficiency

OBJECTIVE

To assess the outcomes of maxillomandibular advancement (MMA) for the treatment of persistent obstructive sleep apnea syndrome (OSA) after phase I reconstruction in patients who do not have maxillomandibular deficiency.

METHODS

From January 1997 to September 1998, 25 patients previously treated with phase I reconstruction (uvulopalatoplasty, genioglossus advancement, and/or hyoid suspension) who did not have maxillary and mandibular deficiencies underwent MMA for persistent OSA. Variables examined include age, sex, body mass index (BMI), respiratory disturbance index (RDI), lowest oxygen saturation (LSAT), and cephalometric data. In addition, a minimum of 6 months after surgery, questionnaires containing a 10-cm visual analogue scale (0 = no change, 10 = drastic change) were mailed to the patients. The questionnaire subjectively assessed the patient's perception of the facial appearance after surgery, whether there was pain or discomfort of the temporomandibular joint, the overall satisfaction with the treatment outcomes, and whether the patient would recommend the operation to other patients.

RESULTS

Nineteen (76%) questionnaires were completed and returned by 15 men and 4 women. The mean age was 45.3 +/- 6.6 years and the mean BMI was 33.1 +/- 7.1 kg/m2. The mean RDI improved from 63.6 +/- 20.8 to 8.1 +/- 5.9 events per hour, and the mean LSAT improved from 73.3 +/- 13.2% to 88.1 +/- 4.1%. One patient was defined as an incomplete responder (RDI >20). One patient reported transient pain and discomfort of the temporomandibular joint. Although all of the patients felt that there were changes in their facial appearance after surgery, 18 of the 19 patients gave either a neutral or a favorable response to their facial esthetic results. All of these patients were satisfied with the overall outcomes and would recommend the treatment to others.

CONCLUSION

MMA is a highly effective treatment for persistent OSA after phase I surgery in patients who otherwise do not have maxillomandibular deficiency. The patient satisfaction is extremely high. Furthermore, previous concerns of unfavorable postoperative facial esthetics and temporomandibular joint dysfunction do not appear to be significant.

Measurement of structure-dependent K+ --> &mgr;(+)nu(&mgr;)gamma decay

We report the first measurement of a structure-dependent component in the decay K+-->&mgr;(+)nu(&mgr;)gamma. Using the kinematic region where the muon kinetic energy is greater than 137 MeV and the photon energy is greater than 90 MeV, we find that the absolute value of the sum of the vector and axial-vector form factors is |F(V)+F(A)| = 0.165+/-0.007+/-0.011. This corresponds to a branching ratio of B(SD+) = (1.33+/-0.12+/-0.18)x10(-5). We also set the limit -0. 04<F(V)-F(A)<0.24 at 90% C.L.

On the concentrations of cyclins and cyclin-dependent kinases in extracts of cultured human cells

Cyclins and cyclin-dependent kinases (CDKs) are key regulators of the human cell cycle. Here we have directly measured the concentrations of the G(1) and G(2) cyclins and their CDK partners in highly synchronized human cervical carcinoma cells (HeLa). To determine the exact concentrations of cyclins and CDKs in the cell extracts, we developed a relatively simple method that combined the use of (35)S-labeled standards produced in rabbit reticulocyte lysates and immunoblotting with specific antibodies. Using this approach, we formally demonstrated that CDC2 and CDK2 are in excess of their cyclin partners. We found that the concentrations of cyclin A2 and cyclin B1 (at their peak levels in the G(2) phase) were about 30-fold less than that of their partner CDC2. The peak levels of cyclin A2 and cyclin E1, at the G(2) phase and G(1) phase, respectively, were only about 8-fold less than that of their partner CDK2. These ratios are in good agreement with size fractionation analysis of the relative amount of monomeric and complexed forms of CDC2 and CDK2 in the cell. All the cyclin A2 and cyclin E1 are in complexes with CDC2 and CDK2, but there are some indications that a significant portion of cyclin B1 may not be in complex with CDC2. Furthermore, we also demonstrated that the concentration of the CDK inhibitor p21(CIP1/WAF1) induced after DNA damage is sufficient to overcome the cyclin-CDK2 complexes in MCF-7 cells. These direct quantitations formally confirmed the long-held presumption that CDKs are in excess of the cyclins in the cell. Moreover, similar approaches can be used to measure the concentration of any protein in cell-free extracts.