Gas formation. Formation temperatures of thermogenic and biogenic methane.

Methane is an important greenhouse gas and energy resource generated dominantly by methanogens at low temperatures and through the breakdown of organic molecules at high temperatures. However, methane-formation temperatures in nature are often poorly constrained. We measured formation temperatures of thermogenic and biogenic methane using a "clumped isotope" technique. Thermogenic gases yield formation temperatures between 157° and 221°C, within the nominal gas window, and biogenic gases yield formation temperatures consistent with their comparatively lower-temperature formational environments (<50°C). In systems where gases have migrated and other proxies for gas-generation temperature yield ambiguous results, methane clumped-isotope temperatures distinguish among and allow for independent tests of possible gas-formation models.

Bilateral idiopathic Brown's syndrome with delayed onset in the second eye.

PURPOSE: We describe 6 cases of a previously unreported variation of bilateral Brown's syndrome that presented in congenital form in one eye and developed later in the fellow eye with no underlying cause. METHODS: We reviewed the clinical records of 6 patients from 6 separate practices to determine whether there were any common clinical features on presentation or in their clinical courses. RESULTS: All 6 patients were diagnosed with unilateral congenital Brown's syndrome at the first ophthalmologic assessment but showed no evidence of the syndrome in the fellow eye. In 5 cases the contralateral syndrome developed in the second eye after surgery was performed on the first eye, and in 1 case it developed before any surgery was done. The ages at onset of the syndrome in the second eye ranged from 2 to 8 years. None of the children had any evidence of systemic illness or local orbital disease to explain an acquired Brown's syndrome. CONCLUSION: To our knowledge, this is the first reported series of cases of bilateral Brown's syndrome that manifested sequentially in the eyes with no known causes for an acquired syndrome in the second eye. This finding supports the premise that congenital and acquired Brown's syndrome are on a continuum with a common pathophysiology of restriction of free movement of the superior oblique tendon in the trochlea.

Low-dose methotrexate therapy for childhood sarcoidosis.

OBJECTIVE: To evaluate the effectiveness of low oral doses of methotrexate as a steroid-sparing agent in children with sarcoidosis. STUDY DESIGN: An open-label, noncontrolled trial. Methotrexate was administered orally at a single weekly dose of 10 to 15 mg/m2. Duration of therapy was open ended, but patients received treatment for a minimum of 6 months to be considered as having completed the study. RESULTS: Seven children with biopsy-proven sarcoidosis completed the study. The mean dose of prednisone was successfully tapered from 49 mg/day (1.3 mg/kg) to 18 mg/day (0.5 mg/kg) after 3 months of methotrexate therapy and to 9.9 (0.2 mg/kg) and 7.3 mg/day (0.1 mg/kg) after 6 months and at the end of the follow-up period, respectively. Other clinical and laboratory parameters improved significantly after methotrexate therapy was started. There was significant clinical improvement, as confirmed by the reduction of the clinical severity score from 8 +/- 1.1 to 0.8 +/- 0.5 point after 3 months of methotrexate therapy, and to 0.7 and 0.5 +/- 0.3 point after 6 months and at the end of the follow-up, respectively. Laboratory measurements revealed marked improvement, as reflected by a significant reduction in the erythrocyte sedimentation rate and an increase of hemoglobin values. The mean serum angiotensin-converting enzyme activity dropped significantly. No adverse side effects were noted with methotrexate therapy. CONCLUSION: Our study demonstrated that low-dose oral methotrexate therapy was effective and safe and had steroid-sparing properties in seven children with sarcoidosis.

Rhabdomyosarcoma presumed metastatic to the orbit.

BACKGROUND: Orbital metastasis from rhabdomyosarcoma is a rare disorder with a poor prognosis for long-term survival. Only one other detailed account of this disorder has appeared in the ophthalmic literature. METHODS: The authors report the clinical features of four patients with presumed orbital metastasis from alveolar and embryonal rhabdomyosarcoma. RESULTS: The most common ophthalmic manifestations of orbital metastasis from rhabdomyosarcoma in these patients included proptosis, reduced visual acuity, orbital pain, and motility disorders. Computed tomography documented orbital masses in all of the patients. In those patients with a primary tumor of the maxillary sinus, there was no evidence of direct extension into the orbit. Despite combination chemotherapy and radiation, all four patients died of their illness within 6 months of orbital metastasis. CONCLUSIONS: Although uncommon, rhabdomyosarcoma should be considered in the differential diagnosis of metastatic tumors to the orbit in children and adults. Despite the poor prognosis, prompt diagnosis and palliative radiotherapy may improve the quality of life for these patients with terminal disease.

Effects of estradiol on lipoprotein lipase activity and lipid availability in exercised male rats.

The effects of 17 beta-estradiol 3-benzoate (10 micrograms.0.1 ml sunflower oil-1 x 100 g body wt-1) and exercise on tissue lipid content and lipoprotein lipase (LPL) activity were determined in male rats. Estradiol administration significantly (P < 0.05) increased fatty acid contents of resting adipose, plasma, and white and red vastus muscle tissues and red vastus muscle triacylglycerol. Adipose and plasma fatty acids and red and white vastus muscle triacylglycerol were significantly higher in exercised estradiol-administered animals than in exercised oil-administered animals. Estradiol administration significantly reduced resting adipocyte LPL activity by 71% and increased myocardial LPL activity by 96%. After exercise, red vastus LPL activity was significantly increased by 76% in estradiol-administered animals compared with oil-administered animals. Ratios of red vastus to adipose LPL activity and myocardial to adipose LPL activity at rest and after exercise were significantly greater in estradiol-administered than in oil-administered animals. Estradiol administration significantly increased the ratio of white vastus to adipose LPL activity of exercised animals. These data indicate that estradiol increases the availability of lipid substrate to exercising muscle from multiple sources, including adipose, plasma, and intracellular muscle triacylglycerol. The absolute increases in muscle LPL activity, combined with a greater ratio of muscle to adipose LPL activity, lead to increased distribution of plasma triacylglycerol-derived fatty acids toward muscle.

Effect of estradiol on the temporal pattern of exercise-induced tissue glycogen depletion in male rats.

The effect of 17 beta-estradiol 3-benzoate (10 micrograms.01 ml of sunflower oil-1 x 100 g body wt-1) on the temporal pattern of exercise-induced tissue glycogen depletion and tissue lipid availability during submaximal treadmill running was determined in male rats. Animal were administered estradiol or oil for 5 days and were then time matched for motorized treadmill running for 30, 60, 90, or 120 min. Significant depletion of liver, soleus muscle, and red and white vastus lateralis muscle tissue glycogen occurred in oil-administered animals run between 30 and 120 min. The greatest extent of tissue glycogen depletion occurred during the first 30 min of exercise with the rate of glycogen depletion slowing between 30 and 120 min of exercise. Administration of estradiol attenuated the temporal pattern of glycogen depletion in both liver and muscle tissues. Significant depletion of red and white vastus glycogen of estradiol-administered animals did not occur until 90 and 120 min of exercise, respectively. Administration of estradiol significantly increased resting plasma free fatty acids and red and white vastus triacylglycerol content. These data indicate that estradiol administration for 5 days resulted in significant glycogen sparing of liver and muscle tissues during submaximal treadmill running for up to 120 min by altering the temporal pattern of glycogen depletion of male rats secondary to an estradiol-mediated increase in availability of lipid substrate during exercise.

Effect of estradiol on tissue glycogen metabolism and lipid availability in exercised male rats.

The effect of 17 beta-estradiol 3-benzoate (10 micrograms.0.1 ml sunflower oil-1.100 g body wt-1) on exercise performance, tissue glycogen utilization, and lipid availability was determined in male rats. In experiment 1, estradiol or oil was administered 1 h or 1-6 days before a treadmill run to exhaustion. No differences in body weight between oil- and estradiol-administered animals were observed during the 6-day treatment. Animals receiving estradiol for 3-6 days ran significantly longer and completed more work than oil-administered animals. Significant degradation of red and white vastus muscle, myocardial, and liver glycogen was observed in all animals run to exhaustion. In experiment 2, animals were administered estradiol for 5 days and then run for 2 h. The submaximal run for 2 h significantly reduced tissue glycogen content in red and white vastus muscle, heart, and liver of oil-administered animals. The latter effect was attenuated in both vastus muscles, liver, and myocardial tissues in the estradiol-administered animals. Estradiol administration significantly increased plasma fatty acids and lowered plasma lactate during the submaximal run. These data indicate that when body weight remained constant between groups of male rats, estradiol administration for 3-6 days increased exercise performance. Furthermore, estradiol administration for 5 days resulted in greater lipid availability and less tissue glycogen utilization during submaximal running for 2 h.

Delayed conjunctival closure in adjustable sutures.

We describe a technique for delayed conjunctival closure in adjustable strabismus surgery. It combines many of the advantages of the limbal and cul-de-sac approaches, while eliminating many of the disadvantages.

Toxocara canis infestation. Clinical and epidemiological associations with seropositivity in kindergarten children.

We studied a cohort of 333 children in kindergarten to determine the prevalence of seropositivity to Toxocara canis, and to detect and measure chronic health effects that might be attributable to past infection. We found that 23.1% of the children had serologic evidence of infection (antibody titer greater than or equal to 1:32), assayed by means of an enzyme-linked immunosorbent assay. Black children were more frequently infested than white children, as were children of parents who did not graduate from high school. In a subsample of seropositive and seronegative children, we found associations between seropositivity and both pica and puppy ownership; we did not find differences in the symptoms and signs that occur in toxocaral visceral larva migrans nor differences in measures of growth and nutrition. No child had ocular toxocariasis although 31.8% (106) of the children had antibody titers greater than or equal to 1:16. In a population in which approximately 20 to 30% of the children show serologic evidence of Toxocara infestation, care must be taken in differentiating toxocariasis-like ophthalmic lesions, due to the potential for the coincidental occurrence of retinoblastoma in a child who is seropositive for the Toxocara parasite.

Epikeratophakia in children with traumatic cataracts.

Epikeratophakia provides a permanent optical correction for aphakia in children with congenital or traumatic cataracts; suturing the epikeratophakia graft onto the cornea eliminates the problems of contact lens or spectacle non-compliance in these young and generally uncooperative patients and provides tectonic support to scarred and irregular corneas. Eighteen children under the age of six years underwent epikeratophakia for the correction of aphakia after the removal of trauma-induced cataracts. Graft success rate was 88%; the average change in keratometry in the patients with successful grafts was 14.82 +/- 2.0 diopters. In the 13 patients eligible for visual acuity tabulation, preoperative acuities ranged from light perception to 20/200, and postoperative acuities ranged from hand motions to 20/30. Ten (77%) had acuities of 20/80 or better. Poor results in three patients with less than 20/200 acuities were likely the results of non-compliance with amblyopia therapy. Present work indicates that in cases of traumatic cataract, the epikeratophakia procedure facilitates amblyopia therapy and decreases the astigmatism in scarred and irregular corneas.