Diffusive resistance to O2 transport in muscle

Although it has been generally well-accepted since the work of August Krogh at the start of the 20th century that O2 travels between muscle microvascular red cells and muscle mitochondria by diffusion, the importance of this process to maximal O2 flux remains in question. This review presents data that suggest maximal rates of diffusion of O2 in muscle are limited by both the amount of capillary structure and the haemoglobin concentration in the blood. On the other hand, diffusional conductance appears unrelated to muscle fibre size and thus to distance. Functional data further suggest that the limited rate of diffusion acts to constrain O2 unloading from muscle capillaries and thus also maximal Vo2, at least in the trained state. In fact, the calculated sensitivity of VO2max to muscle diffusional conductance is about as great as that for muscle blood flow. While additional impairment of O2 unloading from perfusion/metabolism heterogeneity cannot yet be excluded (for lack of methodology), it seems evident that the process of O2 transport between the muscle microvasculature and the mitochondria is subject to significant limits, even in health, that have substantial effects on maximal Vo2.     

Randomized trial of sertraline in patients with unexplained chest pain of noncardiac origin

BACKGROUND: Between 10% and 30% of patients with symptoms similar to angina and sufficient to justify cardiac catheterization are found to have normal coronary angiograms. Treatment of patients with chest pain with no apparent cardiac cause is a major clinical problem. Our hypothesis was that sertraline would reduce the severity of pain in patients with chest pain of noncardiac origin. METHODS AND RESULTS: This was a single-site, double-blind, placebo-controlled study of the efficacy, tolerability, and safety of sertraline in the treatment of noncardiac chest pain in outpatients. Thirty patients were enrolled in the study. After 1 week of single-blind placebo washout, patients were randomly assigned in a double-blind fashion either to drug or placebo. The Beck Depression Inventory was administered at baseline and at completion of study. Daily pain diaries (visual analogue scale, rating pain on a scale of 1 to 10) were selfadministered and evaluated at baseline and at follow-up visits. Statistical measures were performed with an intention-to-treat approach. Patients who received sertraline over the course of the study showed a statistically significant reduction in pain compared with those who were receiving placebo. CONCLUSIONS: The use of sertraline in patients with noncardiac chest pain produced clinically significant reduction of daily pain. These results suggest the need for further studies of the efficacy and tolerability of sertraline and other selective serotonin reuptake inhibitors in the long-term management of noncardiac chest pain.     

Long-term results: botulinum for sixth nerve palsy

Eight patients with intracranial malignancies or vascular lesions and sixth nerve palsies were treated with botulinum toxin chemodenervation of the antagonist medial rectus muscle. Primary deviation ranged from 20 to 75 prism diopters (pd) of esotropia. Six were treated acutely (within 3 months of onset) and two, which demonstrated partial recovery of lateral rectus function but with residual esotropia and diplopia, were treated after 6 months. After a mean follow-up of 20.6 months, seven were diplopia-free with excellent rotations. Five had complete resolution of the esotropia and diplopia, with near complete recovery of abduction. One had 6 pd residual esotropia, while another, whose sixth nerve had been resected, required a modified Jensen procedure, resulting in full rotations. The single case of bilateral sixth nerve palsy had a functional improvement but was lost to follow-up. One patient had a vertical strabismus induced with the injection and had a gradual return of the esotropia.     

Down syndrome. Clinical review of ocular features

A total of 187 medical records of Down syndrome individuals over a 10-year period were reviewed retrospectively for strabismus, myopia, hyperopia, astigmatism, nystagmus, cataract, glaucoma, and other significant eye findings. This study showed that a higher proportion of these individuals than reported in previous studies had strabismus (57%). Refractive errors of myopia (22.5%), hyperopia (20.9%) and astigmatism (22%) were common. The primary care physician needs to be aware of the specific eye problems of Down syndrome individuals so that he or she may initiate or refer the patient for appropriate ophthalmologic care, because most of the eye findings in Down syndrome are treatable. Significant visual loss, a usually avoidable event in Down syndrome, should occur rarely.     

A survey of severe eye injuries in children

We reviewed the medical records of 258 children from newborn to 20 years of age who had ocular injuries severe enough to warrant admission to United Hospitals Medical Center, Newark, NJ, over a 3 1/2-year period. In this time there were 1737 pediatric admissions for eye treatment and of these, 258 (14.85%) were directly related to trauma. Only strabismus, with 676 (38.9%) admissions, accounted for more pediatric hospitalizations for eye injuries. Balls, fists, and sticks were the most common causes of injury, and the most common diagnosis was hyphema. The majority of injuries occurred in children between 11 and 15 years of age (31%). Ocular injuries in children above 10 years of age were most commonly sports-related, whereas injuries in the home accounted for the majority of trauma in children younger than 10 years of age.     

Plasma levels of eosinophil granule major basic protein in pregnant cynomolgus monkeys.

The sera of all pregnant women contain increased amounts of a protein biochemically and immunologically similar to the eosinophil granule major basic protein (MBP). Immunofluorescence shows that the pregnancy-associated MBP is localized to placental trophoblastic cells. This information raises important questions about the function of pregnancy-associated MBP because of the potential biological functions attributed to its eosinophil counterpart (namely, its potent toxic and cytostimulatory activities). Previous studies demonstrated the presence of an immunologically cross-reactive protein in the placentae and plasma of pregnant non-human primates. Here, plasma MBP levels were measured throughout gestation in cynomolgus monkeys. In early pregnancy, only modest increases in MBP were found in contrast to the sharp rise observed in the first 20 weeks of human pregnancy. During the final one-third of gestation, striking increases in plasma MBP occurred in the monkeys. This parallels the late rise in MBP seen in humans in the third trimester. Thus, the cynomolgus monkey may serve as a model to clarify the role of the MBP in the biochemical events that culminate in parturition.     

Transmandibular approaches to the oral cavity and oropharynx. A functional assessment.

The records of patients undergoing transmandibular approaches to soft-tissue carcinoma of the oral cavity and oropharynx were reviewed retrospectively. Thirty-nine patients requiring lateral segmental hemimandibulectomy and 45 patients requiring a mandibulotomy were identified. None of the patients given mandibulectomy underwent bone reconstruction, while all of the patients with mandibulotomy had repair at the completion of the case. A total of 53 patients were available for recall and functional assessment. Patients with mandibulotomy did not experience significant dysfunction of the temporomandibular joint. Patients with mandibulectomy demonstrated increasing amounts of eccentric occlusion; however, this did not affect diet and was not reported to be uncomfortable by these patients. When feasible, preservation of the mandible yielded an improved aesthetic result; however, functional results in patients requiring mandibulectomy compare favorably with those obtained after mandibulotomy and repair.