Rac1 is crucial for Ras-dependent skin tumor formation by controlling Pak1-Mek-Erk hyperactivation and hyperproliferation in vivo

Rac1 has a role in proliferation and survival of tumor cells in vitro. The exact effects of Rac1 on growth, apoptosis and corresponding signaling pathways during tumorigenesis in vivo, however, have not been explored yet. Using mice with a keratinocyte-restricted deletion of the Rac1 gene, we found that Rac1 is essential for DMBA/TPA-induced skin tumor formation. This corresponded to a decreased keratinocyte hyperproliferation, although apoptosis was not detectably altered. Activated Rac1 promoted Erk-dependent hyperproliferation by Pak1-mediated Mek activation independent of Mek1 phosporylation at serine 298. Rac1 was furthermore required for Pak2-dependent hyperactivation of Akt, which under in vivo condition was restricted to the suprabasal cell layers corresponding to a suprabasal-specific expression of Pak2. It is surprising that none of these signaling pathways was altered in untreated Rac1-deficient skin, indicating a hyperproliferation-specific function of Rac1 in vivo. These data suggest that blocking of Rac1 function might allow tumor-specific growth repression, as Rac1 is not required for normal growth and growth signaling controlling pathways in skin in vivo.

The comparative effectiveness of isokinetic and isotonic strength trainings on quadriceps maximum power

The present study compares the effectiveness of isokinetic and Isotonic exercises on maximum power of quadriceps in 45 healthy young males. The subjects were randomly assigned into three groups (n=15): Group A- Isokinetic group, Group B- Isotonic group, Group C-Control group. Maximum power of quadriceps at velocities of 220°/sec, 160°/sec 100°/sec and 40°/sec was tested twice with a gap of 4 weeks using isokinetic dynamometer. The isokinetic protocol consisted of one set of ten repetitions at velocities of 220°/sec, 160°/sec, 100°/sec, and 40°/sec each while, the Isotonic protocol included three sets of 10 repetitions at 50% 10 RM, 75% 10 RM and 100% 10 RM. Each exercise protocol was performed thrice a week for four weeks with 1 minute rest interval. The subjects in the control group were not prescribed any kind of exercise training. Paired t-test showed significant changes at 220°/sec (t=7.15, p<0.001), 160°/sec (t=7.54, p<0.001), 100°/sec (t=9.24, p<0.001) and 40°/sec (t=7.59, p<0.001) in Group A, also at 2200/ sec (t=8.56, p<0.001), 160°/sec (t=8.80, p<0.001), 1000/ sec (t=10.11, p<0.001) and 40°/sec (t=10.50, p<0.001) in Group B and non-significant changes in Group C. Post-test One way ANOVA revealed significant changes at 220°/sec (F= 10.85, p<0.001), 160°/sec (F=16.96, p<0.001), 1000/ sec (F=14.60, p<0.001) and 40°/sec (F=14.00, p<0.001). Isotonic exercises were found to be more effective than Isokinetic exercises in increasing the maximum power at high velocity.

Tracing the response of subcutaneous fat accumulation in two generations of males

The present study included 414 adolescent boys aged 11-17 years and their fathers who volunteered as subjects. All the subjects belonged to Punjabi speaking Khatri, an endogamous urban population residing in Delhi, India. A set of five skinfold thicknesses: biceps, triceps, subscapular, suprailiac and medial calf along with body weight and stature were taken on all the subjects to report the pattern of subcutaneous fat distribution and responsiveness of different skinfold sites to fat deposition with variation in total body fat content. It has been noticed that 16- and 17-year-old sons assumed the pattern of subcutaneous fat distribution of their fathers, which was in favour of trunkal fat. Responsiveness of the five skinfold sites towards deposition of fat varied from site to site in various age groups with suprailiac skinfold sites found to be the most responsive followed by subscapular site. The sensitivity of skinfold sites to fat deposition with increase in weight was found to be greater in middle aged men (fathers) than growing boys (adolescent sons).

Testicular torsion: a race against time

Torsion of the testis is a medical emergency that is most commonly encountered in adolescents. Patients usually present with sudden onset scrotal pain associated with nausea and vomiting. On physical examination the involved testis is tender, high riding and usually horizontal. The cremasteric reflex is usually absent. If left untreated irreversible ischaemia starts appearing in 6 h. Doppler ultrasound is the diagnostic imaging of choice. The ideal treatment is surgical exploration and orchidectomy with contralateral orchidopexy or bilateral orchidopexy depending on the condition of the affected testis. If surgical options are delayed then manual detorsion should be attempted.