Serotonin concentrations in plasma and variations during the menstrual cycle.

We used a specific and sensitive radioenzymatic method to establish a reference interval for the concentration of serotonin in platelet-poor plasma in 98 healthy volunteers (49 men, 49 women). The interval was 0-11 nmol/L with a median of 2.8 nmol/L. No difference in concentration in relation to sex or age was observed. In a group of eight very old volunteers (ages 86-92 years), however, concentrations were increased. In addition, we monitored the plasma concentrations of serotonin in 20 healthy women (ages 26-45 years) through two menstrual cycles. Periovulatory and premenstrual concentrations were greater than the serotonin concentration at the start of menstruation.     

Steroid glaucoma: corticosteroid-induced ocular hypertension in cats.

This study was undertaken to develop a feline model of corticosteroid-induced ocular hypertension. In the first experiment, eight cats were selected whose intraocular pressure (17 +/- 0.4 mmHg) was consistently below the mean baseline intraocular pressure of our colony (24 +/- 0.5) during the preceding 2 months. Unilateral twice or thrice daily topical application of 10 microliters 1% dexamethasone sodium phosphate caused a gradual intraocular pressure increase that became significant (P less than 0.05) within 2-3 weeks. There was no significant change in body weight, but several eyes developed cataracts. Similar results were obtained with treatment of normotensive cat eyes with dexamethasone, or with 1.0% prednisolone acetate (PredForte) twice a day. Topical application of PGF2 alpha-1-isopropyl ester (0.1 or 0.25 microgram PG equivalent) to such steroid-treated eyes yielded significant intraocular pressure reduction and pupillary miosis, similar in magnitude to those exhibited by normal eyes. When dexamethasone treatment was reduced to once daily, after prolonged twice daily treatment, intraocular pressure decreased only slightly within 10 days. When dexamethasone treatment was stopped, intraocular pressure declined to normal levels within 6-7 days. These findings show that adult cat eyes develop steroid-induced ocular hypertension that is maintained and reversible. As opposed to previous findings on rabbits, steroid-induced feline ocular hypertension appears to be a good model for this clinical condition and may be suitable for the testing of potential glaucoma drugs.     

The different contributions of local luminance decreases and increases to the pattern electroretinogram (PERG).

The typical pattern-onset-offset stimulus (stimulus A) consisting of local luminance increases and decreases was broken down into stimuli presenting only local luminance increases (stimulus B) or only local luminance decreases (stimulus C). With stimulus B the onset ERGs are luminance responses. With stimulus C the onset ERGs are pattern-related responses showing a spatial band-pass function. With stimulus A the response is a linear addition of responses to stimuli B and C. The simultaneously recorded VEP is a pattern-related response with all three stimuli (A-C).     

Shape of the myopic eye as seen with high-resolution magnetic resonance imaging.

We have obtained multislice magnetic resonance (MR) images of the eye and calculated ocular dimensions along the three cardinal axes: antero-posterior (A-P), equatorial, and vertical. We found no difference in the shape of hyperopic (average refractive error: +3.72 D) and emmetropic eyes, both of which had an equatorial diameter longer than the A-P and vertical diameters. Myopic eyes (average refractive error: -6.54 D) were larger than hyperopic eyes, and most had the same spheroelliptical shape as that of the emmetropic and hyperopic eyes. The results suggest that during myopic progression an overall enlargement or a radial volume expansion has occurred.     

Toluene vapor exposure and urinary excretion of hippuric acid among workers in China.

A factory survey was conducted in three provinces in China from 1985 to 1989. The time-weighted average toluene concentrations in breathing zone air were monitored by diffusive sampling, whereas hippuric acid (HA) concentrations in shift-end urine samples were measured by high performance liquid chromatography (HPLC). Exposed workers (456 men and women) were those for whom toluene (up to 548 ppm toluene) accounted for greater than or equal to 90% of total exposure (by vapor concentration in ppm), whereas 517 nonexposed controls were recruited from the same factories or from factories of the same region. There was a linear correlation between the intensity of toluene exposure and HA concentration in the shift-end urine. Comparison of the results with findings in the literature shows that the toluene-induced increase in urinary HA concentration among workers in China is significantly smaller than the published values, whereas HA concentrations in urine samples from nonexposed controls are comparable to the levels previously reported.     

Macular recovery time, diabetic retinopathy, and clinical variables after 7 years of improved glycemic control.

Effects of long-term improved glucose control on neurosensory retinal function are investigated. Changes in macular recovery of nyctometry (photostress) are assessed in 45 insulin-dependent diabetic patients between study start and after 7 years prospective follow-up (the Oslo Study). Intensified insulin treatment improved glycosylated hemoglobin (HbA1) from 11.7 +/- 2.2% at start to a 7-year cumulative mean of 9.5 +/- 1.5% (p less than 0.0001). Improved macular recovery performance was observed in patients with 7-year mean HbA1 below 10%, compared to a worsening in those above 10% (p less than 0.001-0.02), and non-proliferative retinopathy progressed less in those with HbA1 below 10%, than in those above (p less than 0.01). Macular recovery at study start did not predict progression or outcome of retinopathy 7 years later. Intraocular pressure fell during the 7 years (p less than 0.001) and was cross-sectionally negatively correlated to macular recovery at the 7-year end-point (p less than 0.001-0.002). Macular recovery was not related to age, duration of diabetes, systemic blood pressure, or urinary albumin excretion level. The study indicates that severity of retinopathy, glycemic control and intraocular pressure are interesting covariants to neurosensory dysfunction in diabetes. Furthermore, the study suggests a critical level of long-term blood glucose or retinopathy, or both, above which neurosensory function of macular recovery is significantly reduced.     

Blinded clinical evaluation of positron emission tomography for diagnosis of probable Alzheimer's disease.

We evaluated the sensitivity and specificity of positron emission tomography for diagnosis of probable Alzheimer's disease under conditions similar to those encountered in the routine clinical practice of nuclear medicine. We obtained tomographic images of regional cerebral blood flow from three groups of subjects: (1) 13 subjects, ages 69 to 84, who had probable Alzheimer's disease diagnosed by validated clinical criteria; (2) 15 subjects, ages 57 to 77, who had Parkinson's disease without dementia; and (3) 11 subjects, ages 65 to 83, who were normal. Three blinded reviewers, who had not previously seen the images, categorized them as normal, bilateral temporoparietal flow defects typical of Alzheimer's disease, or other abnormality. Consensus interpretation demonstrated sensitivity of 0.38 (5/13) and specificity of 0.88 (23/26) for identifying patients with probable Alzheimer's disease. Thus, the criterion of bilateral temporoparietal reduction in cerebral blood flow used in this study did not have sufficient sensitivity to be of clinical value. While other criteria may be developed to improve diagnostic accuracy, clinical utility can be established only by testing for validity in patients with a full spectrum of complicating neurologic and psychiatric conditions for whom diagnosis is uncertain and who are then followed longitudinally to determine clinical outcome or pathologic findings.