Neuromuscular disorder in response to anterior cruciate ligament creep

OBJECTIVE: To determine the effect of creep developed in the anterior cruciate ligament and other viscoelastic knee structures on the function of the flexor and extensor muscles of males and females. DESIGN: Static load applied to the proximal tibia of young healthy male and female subjects in a laboratory setting with maximal voluntary knee flexion and extension performed before and after the load application. BACKGROUND: Static loads applied to various joints during occupational and sports activities are epidemiologically linked to higher than normal rates of disability reports. The physiological and biomechanical processes active in the development of such a neuromuscular disorder are not known. We hypothesize that creep developed in the anterior cruciate ligament due to prolonged static load will have pronounced impact on the reflexive activation of the associated musculature in a manner that may increase the risk of injury. Females are expected to be exposed to higher risk than males. METHODS: Male and female groups performed maximal voluntary knee flexion and extension before and after applying 200 and 150 N, respectively, to the proximal tibia for a 10 min period. Flexion and extension forces as well as electromyograph from agonist and antagonist muscles were measured at 35 degrees and 90 degrees knee flexion. Data was analyzed through repeated measures of analysis of variance. RESULTS: It was found that in extension, quadriceps electromyographic activity increased significantly after anterior cruciate ligament creep while hamstrings co-activation did not change. There was also a trend towards increased extension force after creep was developed, with significant effect of gender (larger increase in females). Similarly, significant increase in hamstrings electromyographic activity and a trend towards increased force during knee flexion was observed but with no effect of gender. Electromyographic spasms from the flexors and extensors were recorded in 30% of the subjects during the 10 min static loading period at 90 degrees angle and from the flexors only at 35 degrees. Creep in the ligament was marginally greater in females than in males with a significant effect of angle, being greater at 35 degrees than in 90 degrees knee flexion. CONCLUSIONS: The results suggest that ligament creep may develop a neuromuscular disorder consisting of spasms, increased electromyography and force in the agonist muscles without compensation from the antagonist. Static loading of a joint, therefore, may develop a neuromuscular disorder compounded with laxity of the ligaments and subject the individual to increased risk of injury. RELEVANCE: The data provides evidence that prolonged static loads applied to the anterior cruciate ligament and associated viscoelastic structures results in unbalanced muscular activation which puts individuals at increased exposure to injury. Work and sports activities should be scheduled while minimizing periods of static joint loading and emphasizing sufficient rest periods to allow recovery of creep and return to balanced muscular activation and co-activation.     

The place of intraoperative antegrade colonic irrigation in emergency left-sided colonic surgery

The healing of colinic or colorectal anastomoses depends, at least partially, on the volume of fecal residue. Intraoperative antegrade colonic irrigation enables the surgeon to prepara the colon adequately at the time of surgery and to perform safely an immediate resection and primary anastomosis in obstructive lesions of the left colon. Its indications have been extended to other left-sided colonic emergencies, especially perforation and hemorrhage. The technique is described in this study and its value is assessed in the light of available experimental and clinical evidence     

Management of cystic prolactinomas: a review

Introduction

Cystic prolactinoma is a variant of prolactin-secreting pituitary adenoma. The strategies for the management of cystic prolactinoma have not been addressed thoroughly in clinical guidelines.

Methods

A literature search was performed using Pubmed to review the current approaches to the treatment of cystic prolactinoma.

Results

Transsphenoidal resection is an effective and relatively safe approach for the treatment of cystic prolactinoma, however, morbidity of surgery is dependent on the skill of the surgeon. Emerging studies allude to the efficacy and safety of dopamine agonists in the management of cystic prolactinoma. Dopamine agonists are associated with considerable rates of clinical improvement and tumor shrinkage, hence reducing the need for surgical intervention.

Conclusions

Recent studies suggest that dopamine agonist therapy may be an effective and safe treatment option in a considerable portion of patients with cystic prolactinomas. We suggest that dopamine agonists should be considered as a first-line therapy for cystic prolactinoma in the absence of indications for early surgical intervention.

     

Hyperinsulinemia induces a reversible impairment in insulin receptor function leading to diabetes in the sand rat model of non-insulin-dependent diabetes mellitus.

The insulin receptor was evaluated at differentdisease stages in the sand rat (Psammomys obesus), a model for nutrition-induceddiabetes. Nondiabetic sand rats showed markedly low receptor number in livercompared with albino rats. Their receptor had an intact tyrosine kinase activitybut a higher Km for ATP in the phosphorylation reaction of exogenous substrates.The initial effects of overeating (i.e., development of hyperinsulinemia withouthyperglycemia) were associated in the sand rat with a dramatic decrease in invitro and in vivo insulin-induced receptor tyrosine kinase activity in bothliver and muscle. In muscle, this coincided with a decrease in receptor numberand an increase in basal tyrosine kinase activity. Similar changes were observedupon development of hyperinsulinemia with hyperglycemia. Upon recovery from thediabetic state by diet restriction, the impaired receptor kinase activation wascorrected. Complete restoration occurred only in animals that fully recoveredfrom the diabetic state and became normoinsulinemic. These observations indicatethat loss and gain of receptor tyrosine kinase activity were dependent oninsulin levels. Thus, overeating may lead to the development of hyperinsulinemiathrough ineffective extraction of excess insulin by the scarce liver receptors.Hyperinsulinemia, in turn, causes a reversible reduction in receptor kinaseactivity, leading to insulin resistance. This sequence of events may be relevantto diet-related changes in human non-insulin-dependent diabetesmellitus.