Search

Colony size in social insects is one of the most important factors in shaping their self-organized system. It affects a wide variety of traits such as foraging and defense strategies, social immune responses, the degree of polymorphism, and reproductive output. However, colony size estimation of subterranean termites in the field has been challenging, due to their extremely cryptic biology and multiple site-nesting behavior. Since natural selection favors workers that maximize the number of their siblings, the amount of egg production may reflect the number of workers in the colony. Here, we report a method for inferring colony size in the field using total egg production in each colony from a subterranean termite, Reticulitermes speratus. Our investigation of field colonies revealed that the body weight of queens reaches a peak and had the largest variance in June and July and accurately predicts the number of eggs laid by the queen per 24 h. Using laboratory-reared colonies, we found that the total egg production in each colony is proportional to the number of workers. We also estimated the colony size of 198 field colonies and found that the median and maximum colony size was 24,500 and 451,800 workers per colony. The method for inferring colony size presented here may also be applicable to termite species with a clear seasonality in egg production. The colony size estimate will contribute to understanding the life history strategies and social systems of termites., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Purpose: The usefulness of endoscopic ultrasound (EUS) in pediatric populations has been recently appreciated; however, published studies on mini-probe EUS in the diagnosis of congenital esophageal stenosis (CES) or congenital duodenal stenosis (CDS) in pre-school patients remain scarce. This study aimed to report the utility of mini-probe EUS for the diagnosis of CES or CDS in pre-school patients based on the etiology., Methods: We retrospectively reviewed the medical records of pediatric patients with CES or CDS who underwent mini-probe EUS through the stenotic segments at our hospital between December 2006 and December 2021., Results: Five patients with CES and one with CDS were enrolled. The median age and body weight when EUS was performed were 12.5 months and 8.5 kg, respectively. Hypoechoic lesions were observed on EUS in three patients, which were assessed as cartilage; one patient had no hypoechoic lesion but had a focal thickness of the muscular layer. They were diagnosed with tracheobronchial remnants based on EUS. The full circumferential wall thickness of the esophagus was visualized in one patient with fibromuscular hypertrophy. The histopathological findings confirmed the diagnoses. In the patient with CDS, EUS findings revealed pancreatic parenchyma encircling the stenotic part of the duodenum. The preoperative diagnosis was annular pancreas. The patient underwent duodenoduodenostomy, and intraoperative findings confirmed the diagnosis., Conclusion: Mini-probe EUS can be recommended as a feasible and safe technique for infants and toddlers. It can effectively diagnose CES or CDS based on etiology and can inform treatment strategies for pre-school patients., (© 2023. The Author(s), under exclusive licence to The Japan Society of Ultrasonics in Medicine.)

The purpose of this study was to investigate the effect of high-intensity and low-intensity resistance training upon bone mineral density (BMD) by comparing the BMD of young male powerlifters (n = 5), recreational trainees (n = 5), and controls (n = 5). Lumbar spine (L2-L4), proximal femur, and whole body BMDs were measured using dual-energy X-ray absorptiometry (DXA). The high-intensity group showed a significantly greater BMD when the whole body and trochanter regions were measured than the low-intensity and control group. The BMD of the lumbar spine, femoral neck, and Ward's triangle was greater in the high-intensity group compared with the control group. There was no significant BMD difference between the low-intensity and control group except at the trochanter region. These results suggest that high-intensity resistance training is effective for increasing BMD, but low-intensity resistance training is not.

The effects of high-intensity resistance training on bone mineral density (BMD) and its relationship to strength were investigated. Lumbar spine (L2-L4), proximal femur, and whole body BMD were measured in 10 male powerlifters and 11 controls using dual-energy X-ray absorptiometry (DXA). There were significant differences in lumbar spine and whole body BMD between powerlifters and controls, but not in proximal femur BMD. A significant correlation was found between lumbar spine BMD and powerlifting performance. These results suggest that high-intensity resistance training is effective in increasing the lumbar spine and whole body BMD.

Activation of cardiac muscarinic receptors by vagal stimulation decreases cardiac work, which may have a protective effect against ischemic injury. To determine whether cardiac muscarinic receptors contribute to the mechanisms of preconditioning effects, we examined the effect of carbachol on ischemia/reperfusion damage and the effect of vagotomy on cardioprotection induced by ischemic preconditioning. Rats were subjected to 30 min of left coronary artery occlusion followed by 30-min reperfusion in situ. Pre-conditioning was induced by three cycles of 2-min coronary artery occlusion and, subsequently by 5 min of reperfusion. The incidence of ischemic arrhythmias, such as ventricular tachycardia (VT) and ventricular fibrillation (VF), and the development of myocardial infarction were markedly reduced by the preconditioning. Carbachol infusion (4 micrograms/kg per min) delayed the occurrence of VT and VF during ischemia and reduced the infarct size. Compared with non-ischemic left ventricle, the cyclic guanosine monophosphate (GMP) content in the ischemic region of the left ventricle was decreased by ischemia/reperfusion, whereas the cyclic adenosine monophosphate (AMP) content of this region was increased. These changes were reversed by preconditioning. Similar changes in cyclic GMP and AMP content in the ischemic region were seen in rats undergoing carbachol treatment. These results suggest the possible contribution of muscarinic receptor stimulation to preconditioning. Vagotomy prior to preconditioning diminished the antiarrhythmic effects, whereas it did not block the anti-infarct effect afforded by pre-conditioning. Vagotomy abolished the preconditioning effect on the tissue cyclic GMP, but it did not attenuate the decrease in tissue cyclic AMP. The results suggest that muscarinic stimulation exerts preconditioning-mimetic protective effects in ischemic/reperfused hearts, but that a contribution of reflective vagal activity to the mechanism for preconditioning is unlikely.

The present study was undertaken to determine whether or not tissue glycogen depletion prior to ischemia, and subsequent attenuation of tissue lactate accumulation during ischemia, correlates with postischemic functional recovery of the preconditioned heart. Isolated rat hearts were subjected to 40-min ischemia and 30-min reperfusion. Preconditioning with 5-min ischemia and 5-min reperfusion reduced the preischemic glycogen and postischemic lactate levels of the heart to 60.5 +/- 5.6% and 66.9 +/- 7.7% respectively, of values in non-preconditioned hearts (n = 6), and improved the recovery of the rate-pressure product (RPP) of the ischemic/reperfused heart (87.0 +/- 5.8% versus 25.2 +/- 4.5% of the initial value for the non-preconditioned group, n = 8). Treatment with polymyxin B (50 microM) abolished the preconditioning-induced postischemic recovery of the RPP. Treatment of the non-preconditioned heart with phorbol 12-myristate 13-acetate (15 pmol/5 min) resulted in an improvement in the postischemic recovery of RPP. Neither of these treatments affected the preischemic glycogen and postischemic lactate levels. The results suggest that preischemic glycogen depletion and subsequent attenuation of ischemic lactate accumulation do not play a major role in the preconditioning-induced protection against postischemic contractile dysfunction in perfused rat hearts.

Activation of the adenosine A1(A1) receptor, Gi protein, and ATP-sensitive K+ (KATP)-channel system has been shown to play an important role in the cardioprotective effects of ischemic preconditioning in dogs. The present study was undertaken to elucidate the possible involvement of this system in hypoxic preconditioning, which ameliorates injury induced by prolonged ischemia and subsequent reperfusion in perfused rat hearts. Ten minutes of hypoxic preconditioning resulted in an appreciable improvement of post-ischemic cardiac contractile recovery. This was associated with a significant reduction in the release of creatine kinase (CK) from reperfused hearts. Hypoxic preconditioning shortened the time to ischemic contracture onset and prevented a further rise in left ventricular end-diastolic pressure (LVEDP) during reperfusion. Neither the selective A1 receptor antagonist, 8-cyclopentyltheophylline (CPT) nor the KATP channel blocker, glibenclamide, altered the beneficial effects of hypoxic preconditioning. In vivo pretreatment with an inhibitor of Gi protein, pertussis toxin (PTX), also did not diminish the preconditioning effect. The results suggest that, although hypoxic preperfusion ameliorates post-ischemic contractile dysfunction, neither the activation of the A1 receptor, nor the opening of the KATP-channel, nor transduction through Gi protein are involved in the post-ischemic functional recovery of hypoxic preconditioning in the perfused rat heart.

We have investigated, in 6 standing subjects, the time course of amplitude changes in the short latency (40-60 ms) and long latency (60-80 ms) reflex response components of gastrocnemius medialis (GM) and soleus (S) muscles during the preparatory period (time between a warning signal and a response signal) as a function of the precued direction (pull or push) of arm movement. Subjects maintained their standing posture by visual feedback during the 1.5 s preparatory period of a reaction time task. A warning signal gave advance information concerning the voluntary response to be performed which consisted of either a pull or push movement of the right arm. The excitability of the reflex pathways was evaluated by triggering a rapid rotation of the right ankle joint (dorsiflexion) applied randomly at 100, 300 or 500 ms before the response signal for arm movement. Statistical analysis of EMG amplitude (ANOVA) showed that preparatory effects were different for the two synergistic muscles with both short (spinal) and longer latency components of GM showing generalized facilitation and of S showing generalized inhibition. In addition, the longer latency, presumably supraspinal, component of the two muscles was differentially modulated according to directional advance information, showing relative facilitation for pull as compared to push trials. These reflex response modulations were emphasized in faster reaction time (RT) performers at the end of the preparatory period. It is concluded that postural preparatory processes are reflected at the spinal level in global effects and at the supraspinal level in directionally specific effects.

The effects of pre-motion silent period (PSP) on dynamic force exertion were studied in ten healthy subjects performing ballistic elbow extensions. The experiments were designed to evaluate the significance of mean differences between the averaged dynamic force curves of two groups: PSP-presence groups and PSP-absence groups. The presence of PSP was judged quantitatively and automatically by means of a newly developed method using statistical analysis. The results indicated that there were two effects of PSP on dynamic force exertion: one was a reducing effect, observed prior to the movement; the other was a reinforcing effect, observed in the first part of the ballistic movement. The duration of the reinforcement was significantly correlated with the duration of the reducing effect of PSP. The findings suggested that the reinforcement of dynamic force may be produced by the pre-stretch of agonistic muscles caused by prior force reduction due to PSP occurrence. The fact that PSP plays an important role in dynamic force exertion suggests that PSP may be incorporated in the central motor control system designed to interrupt the background activity, to stretch the agonist and to reinforce the dynamic force.