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Biomedical subjects

R L Green

Publications and source records attributed to R L Green.

At least 19 recordsLinked to original sources
PubMed1998

Brain size, head size, and intelligence quotient in monozygotic twins.

Many studies of monozygotic (MZ) twins have revealed evidence of genetic influences on intellectual functions and their derangement in certain neurologic and psychiatric diseases afflicting the forebrain. Relatively little is known about genetic influences on the size and shape of the human forebrain and its gross morphologic subdivisions. Using MRI and quantitative image analysis techniques, we examined neuroanatomic similarities in MZ twins and their relationship to head size and intelligence quotient (IQ). ANOVA were carried out using each measure as the dependent variable and genotype, birth order, and sex, separately, as between-subject factors. Pairwise correlations between measures were also computed. We found significant effects of genotype but not birth order for the following neuroanatomic measures: forebrain volume (raw, p < or = 0.0001; normalized by body weight, p = 0.0003); cortical surface area (raw, p = 0.002; normalized, p = 0.001); and callosal area (raw, p < or = 0.0001; normalized by forebrain volume, p = 0.02). We also found significant effects of genotype but not birth order for head circumference (raw, p = 0.0002; normalized, p < or = 0.0001) and full-scale IQ (p = 0.001). There were no significant sex effects except for raw head circumference (p = 0.03). Significant correlations were observed among forebrain volume, cortical surface area, and callosal area and between each brain measure and head circumference. There was no significant correlation between IQ and any brain measure or head circumference. These results indicate that: 1) forebrain volume, cortical surface area, and callosal area are similar in MZ twins; and 2) these brain measures are tightly correlated with one another and with head circumference but not with IQ in young, healthy adults.

Adult↗
PubMed1997

Annular peripheral choroidal detachment simulating aqueous misdirection after glaucoma surgery.

PURPOSE: The purpose of the study was to define a newly recognized complication after glaucoma surgery and to recommend a therapeutic regimen. METHODS: Eighteen patients diagnosed initially as having aqueous misdirection after glaucoma surgery, but who subsequently were found by ultrasonography to have an annular peripheral choroidal detachment that resulted in secondary angle closure glaucoma, were studied. Ten of these patients were treated with topical cycloplegics and corticosteroids, and 8 were treated with drainage of suprachoroidal fluid. Outcomes of these two treatment methods were compared. RESULTS: Annular peripheral choroidal detachment reliably was diagnosed with ultrasonography. Of the variables studied, time elapsed before resolution of the annular peripheral choroidal detachment was noted to be statistically significant (P < 0.00005). Immediate resolution followed drainage of suprachoroidal fluid, whereas a mean of 19.6 days was required for resolution after medical therapy. CONCLUSIONS: Annular peripheral choroidal detachment should be considered in the differential diagnosis of a flat or shallow anterior chamber with normal or high intraocular pressure after glaucoma surgery. The diagnosis of annular peripheral choroidal detachment can be confirmed most reliably by ultrasonography. Medical therapy is as effective as is surgery, although a significantly longer time to resolution is required.

Adult↗
PubMed1996

How lesioning the nucleus praeeminentialis affects electrolocation behavior in the weakly electric fish, Apteronotus leptorhynchus.

The ability to orient to and track moving electrolocation targets was assessed in normal Apteronotus leptorhynchus and in those with unilateral lesions of the nucleus praeeminentialis dorsalis. 1. Each fish was trained to hover between two vertical metal rods and track their movement. Two aspects of this behavior were measured: a) the hovering position of the fish relative to stationary rods; b) the latency between the onset of rod motion and the fish's tracking response. Control fish hovered midway between stationary rods, while lesioned fish hovered closer to the rod ipsilateral to the lesion. Response latency varied negatively with rod diameter in both sets of fish, and lesioned fish exhibited shorter latencies than control fish. While the response latencies of control fish were shortest when their starting position was midway between the rods, lesioned animals latencies were shortest when they hovered closer to the rod ipsilateral to their lesion. 2. Control fish responded to the approach of a single metal ball to either side of the body with nearly equal latencies and fish-to-object distances. After lesioning, response latency increased and fish-to-object distance decreased for approaches to the side ipsilateral to the lesion; opposite changes occurred for contralateral approaches.

Animals↗
PubMed1996

Posterior vitreoschisis. An echographic finding in proliferative diabetic retinopathy.

PURPOSE: To describe the echographic characteristics of splitting the outer posterior cortical vitreous in patients with proliferative diabetic retinopathy and vitreous hemorrhage. METHODS: The authors retrospectively reviewed the echographic findings in 270 patients who were evaluated at the Doheny Eye Institute between January 1983 to December 1989 for proliferative diabetic retinopathy and vitreous hemorrhage. None of the eyes had undergone pars plana vitrectomy before echographic examination. RESULTS: Forty-five patients (17%) had echographic evidence of splitting of the outer posterior vitreous cortex, a finding the authors have termed posterior vitreoschisis. In all patients, differentiation of the posterior vitreoschisis from a true posterior hyaloid detachment was possible, either on the initial or on serial echographic examination, by the separate detachment of the inner wall of the vitreoschisis cavity and the true posterior hyaloid from the retinal surface. The vitreoschisis cavities often were found to contain unclotted blood. In some eyes, the inner wall of the vitreoschisis cavity was adherent to the apex of the most highly elevated area of traction retinal detachment, suggesting that posterior vitreoschisis may itself result in clinically significant vitreoretinal traction, independent of the presence or extent of true posterior hyaloid separation. CONCLUSIONS: The authors' finding suggest that spontaneous splitting of the outer posterior vitreous cortex may occur in patients with proliferative diabetic retinopathy and vitreous hemorrhage, which may mimic a true posterior cortical vitreous detachment on echographic examination. Preoperative recognition of posterior vitreoschisis may be important in the surgical management of these patients.

Adult↗
PubMed1996

Trimethylamine N-oxidation in Turkish women with bacterial vaginosis.

Bacterial vaginosis (BV) is the most common cause of vaginal discharge in women of child-bearing age. A common symptom of this condition is a fishy-smelling vaginal discharge. Trimethylamine (TMA) is the substance which is primarily responsible for this distinctive odour. The ability to metabolize TMA is polymorphically distributed such that the majority of individuals metabolize a large part of the body burden of TMA to the odourless trimethylamine N-oxide (TMAO) which is excreted in urine with a small amount of TMA. However, in certain individuals, N-oxidation of TMA is impaired which results in the excretion of large amounts of TMA in the urine, breath, sweat and vaginal secretions. In the present study the metabolism of TMA to TMAO was determined in women with clinically diagnosed BV, women with fishy-smelling vaginal discharge but with no other evidence of BV and control women with no evidence of fishy-smelling vaginal discharge. An index of TMA N-oxidation was established for all subjects after analysis of a 24 h urine sample for free TMA and total TMA after reduction of TMAO. We show that, irrespective of diagnosis of BV or not, women with fishy-smelling vaginal discharge excrete significantly more free TMA and have a similarly significantly reduced capacity to N-oxidize TMA when compared to healthy control women. Thus, the results of this study suggest that a woman's ability to metabolize TMA to TMAO is an important factor which predisposes to a fishy-smelling vaginal discharge.

Adolescent↗
PubMed1995

Choroidal effusion as a mechanism for transient myopia induced by hydrochlorothiazide and triamterene.

PURPOSE: We treated a case of transient myopia in a patient being treated with hydrochlorothiazide and triamterene for tinnitus. METHODS: The patient underwent gonioscopic, ophthalmoscopic, and echographic examinations. RESULTS: Examination showed anterior chamber flattening and echography disclosed bilateral 360-degree shallow choroidal detachments. CONCLUSION: All of the patient's symptoms and signs resolved after the cessation of drug therapy.

Adult↗
PubMed1995

Echographic evaluation of primary cysts of the iris pigment epithelium.

PURPOSE: Primary cysts of the iris pigment epithelium frequently appear to be focal elevations of the peripheral iris. To differentiate them from other anterior segment tumors requires the ability to assess the distribution, tissue characteristics, and progression of such lesions, which we accomplished by using anterior segment echography. METHODS: We reviewed the medical records of 49 consecutive patients referred to the Doheny Eye Institute for echographic evaluation of focal bulging of the peripheral iris. Echography of the anterior segment was performed on each patient by using an immersion technique. Clinical examination was also performed on 20 (41%) patients at the time of initial examination. RESULTS: We identified 52 iris pigment epithelial cysts in 52 eyes of the 49 patients studied. All lesions were single, localized to the posterior iris surface, and demonstrated a well-circumscribed, echolucent structure on B-scan echography. Average maximal sagittal thickness was 1.6 +/- 0.4 mm. Cysts were most frequently located in the inferotemporal quadrant (31%). Minimal increase in size or regression of lesions was noted in the nine patients (ten eyes) for whom follow-up echographic examinations were available. CONCLUSIONS: Primary iris pigment epithelial cysts possess characteristic features with regard to location, size, and internal structure, which can be accurately documented with echography. Clinically evident lesions tend to be between 1 and 4 mm in maximum sagittal thickness, conform to the contour of posterior chamber structures without distortion, produce anterior bulging of the peripheral iris, are preferentially located in the inferotemporal quadrant, and demonstrate limited potential for growth.

Adolescent↗
PubMed1994

Echographic findings in infectious endophthalmitis.

OBJECTIVE: To correlate the initial echographic findings in eyes with infectious endophthalmitis with the visual prognosis and causative microorganism. DESIGN: A retrospective review of the clinical and standardized ocular echographic findings in eyes with infectious endophthalmitis was performed. SETTING: University-based ophthalmology department. STUDY PARTICIPANTS: One hundred thirty-seven eyes (136 patients) with infectious endophthalmitis that were evaluated by the ocular echography service of the Doheny Eye Institute, Los Angeles, Calif, between January 1, 1981, and December 31, 1992. RESULTS: Four findings on initial echography were associated with poor initial vision: dense vitreous opacities, retinal detachment, macular detachment, and choroidal detachment. Five findings on initial echography correlated with poor final vision: dense vitreous opacities, vitreous membranes, the presence of retinal detachment, the extent of retinal detachment, and the presence of choroidal detachment. Change (decrease) in vision during the follow-up period was associated with the presence of combined vitreous and subhyaloid opacities, retinal detachment, and choroidal detachment. All eyes with initially clear vitreous on ocular echography had either early streptococcal or culture-negative endophthalmitis. Advanced streptococcal endophthalmitis correlated with the most severe vitreous inflammation, vitreous membranes, and the most extensive posterior vitreous detachment, whereas gram-negative endophthalmitis correlated with choroidal detachment on initial echography. Stepwise logistic regression analysis revealed that the presence of choroidal detachment, not gram-negative microorganisms, was the principal predictor of poor visual outcome in these eyes. CONCLUSION: Ocular echography is a useful method in the clinical evaluation and treatment of infectious endophthalmitis, especially in eyes with opaque media.

Adolescent↗
PubMed1994

Encircling panretinal laser photocoagulation may prevent macular detachment after vitrectomy for proliferative diabetic retinopathy.

Macular detachment due to peripheral retinal tears that occur after pars plana vitrectomy for proliferative diabetic retinopathy can result in severe visual loss despite successful retinal reattachment. The authors reviewed the records of three patients who developed peripheral sclerotomy-related rhegmatogenous retinal detachments one to six months after vitrectomy for proliferative diabetic retinopathy, despite the absence of detectable sclerotomy-related retinal tears by indirect ophthalmoscopy and scleral depression at the conclusion of surgery. All three patients had received standard panretinal laser photocoagulation in a complete encircling pattern either prior to or during the initial vitrectomy. Clinically or echographically, each patient was seen to have a partial or complete annual peripheral sclerotomy-related rhegmatogenous retinal detachment delimited to the equator. In each of these three cases, posterior extension of the peripheral retinal detachment into the macular area was prevented by the most anterior row of the photocoagulation scars. Standard panretinal laser photocoagulation applied in a complete encircling pattern may be useful in the prophylaxis of macular detachment from sclerotomy-related retinal tears that occur after vitrectomy for proliferative diabetic retinopathy.

Aged↗
PubMed1994

Echographic findings in hemorrhagic disciform lesions.

PURPOSE: To examine the potential role of ocular echography in the evaluation of hemorrhagic disciform disease. METHODS: Using standardized ocular echography, the authors examined 85 eyes of 85 patients with hemorrhagic disciform lesions. RESULTS: Hemorrhagic disciform lesions are located in the subretinal pigment epithelial space and appear echographically as solid chorioretinal elevations characterized by a bumpy, lobulated surface with indistinct peripheral margins, irregular internal structure, and medium to high internal reflectivity. These lesions could be reliably differentiated from associated subretinal or suprachoroidal hemorrhage by ocular echography when the maximal height of the lesion was 1 mm or greater. CONCLUSIONS: Hemorrhagic disciform disease is usually complex with distinct components that may not be discernible on biomicroscopic or angiographic examination, in part because of overlying subretinal hemorrhage. Ocular echography provides a readily available clinical tool to define the components of hemorrhagic disciform disease more precisely. Improved characterization of hemorrhagic disciform lesions may improve understanding of the natural history and response to therapy of hemorrhagic age-related macular degeneration.

Aged↗
PubMed1994

Sustained regression of a primary choroidal melanoma under the influence of a therapeutic melanoma vaccine.

PURPOSE: To determine whether active specific immunotherapy with lysates of cutaneous melanoma cells, administered with immunologic adjuvant DETOX (Ribi ImmunoChem Research, Inc, Hamilton, MT), is effective in shrinking a primary choroidal melanoma, in an elderly patient already blind in the nontumorous eye. An 81-year-old man was referred with a primary choroidal melanoma of the left eye, with virtual blindness of the right eye due to macular degeneration. He was begun on active specific immunotherapy with an experimental melanoma vaccine (melanoma theraccine) and DETOX on weeks 1, 2, 3, 4, and 6, respected after a hiatus of 2 weeks. After a response was noted, monthly injections were given. RESULTS: The patient had a significant shrinkage of his choroidal melanoma from a height of 4.2 mm to 2.4 mm within 2 months. This was sustained by continual treatment for 21 months until September 1991. After the patient failed to return for 9 months while recuperating from a stroke, the lesion regrew to a height of 3.7 mm and developed an additional lobe. On resumption of monthly treatments, the lesion shrank to 3.4 mm within 3 months, lost the additional lobe, and has since remained stable. No metastases have been found over a period of nearly 4 years on quarterly computed tomographic (CT) scanning of the chest and abdomen, and magnetic resonance imaging of the head. CONCLUSION: Active specific immunotherapy with cutaneous melanoma lysates has caused a clinically useful protracted regression of a primary choroidal melanoma in an elderly patient in whom surgery and radiation therapy were contraindicated. This may represent the first case of a primary choroidal melanoma, and perhaps the only primary tumor, successfully treated with systemic immunotherapy alone. A formal trial of active specific immunotherapy for primary choroidal melanoma in selected patients may be warranted.

Adjuvants, Immunologic↗
PubMed1993

Effects of caffeine and gender on physiology and performance: further tests of a biobehavioral model.

The present study extended testing of our biobehavioral model describing the effects of arousal and caffeine to include an examination of gender differences and their interactions with habitual and acute caffeine ingestion. Males and females selected as high or low habitual caffeine users were randomly assigned to receive either caffeine or a placebo and exposed to novel and repetitive recall tasks and to simple auditory stimuli. Electrodermal activity and recall task performance were recorded. The four major factors examined, including habitual caffeine use, acute ingestion, gender, and stimulus novelty, affected behavior, physiology, or both. Results showed that habitual caffeine usage systematically affected tonic arousal (skin conductance level) and improved recall task performance. Acute caffeine ingestion increased phasic arousal (skin conductance response amplitude) and reduced habituation rates. Gender interacted with other factors to significantly affect both tonic and phasic arousal, and females performed better than males on the recall tasks. These results were partially supportive of the theoretical model, and further work is needed to examine the interactions of acute and chronic caffeine intake with gender and novelty.

Adult↗
PubMed1993

Echographic evaluation of glaucoma shunts.

BACKGROUND: It is frequently impossible to determine by clinical examination alone if a filtering bleb is present over the equatorial plate(s) of a glaucoma shunt. This uncertainty can result in management dilemmas when patients with these devices have elevated intraocular pressures (IOPs). The authors describe how standardized echography can be used to determine if fluid is present around the plates and to characterize the blebs. METHODS: Four hundred twenty-seven plates in 269 patients who had undergone single- or double-plate Molteno implantation underwent standardized echography (both A- and B-scan examinations) to determine if blebs were present around the plates, primarily when results of slit-lamp examinations had been inconclusive. Bleb sizes, locations, and characteristics also were evaluated. RESULTS: Sixty-five percent of the plates had associated blebs, which were graded according to their sizes (small, medium, and large, in 29%, 44%, and 27% of plates with blebs, respectively). Fluid (which appeared as an echolucent area) could be seen underlying and/or overlying the plates (which appeared as echodense lines). Larger blebs were often associated with scleral flattening. Although bleb sizes did not necessarily correlate with the levels of IOP control, the presence of a bleb on ultrasound was indicative of tube patency. CONCLUSION: Standardized echography was invaluable in the postoperative management of patients who had undergone Molteno implantation because it demonstrated the presence or absence of blebs and characterized them when results of slit-lamp examinations had been inconclusive. This technique also can be used to evaluate similarly designed aqueous shunting devices.

Adult↗
PubMed1993

Pseudo-Brown's syndrome as a complication of glaucoma drainage implant surgery.

Two cases of pseudo-Brown's syndrome occurring after superior nasal implantation of glaucoma filtering devices are described. We hypothesize that this restriction in ocular motility was due to the mechanical effects of large filtering blebs or increased inflammation and scar formation in the superior nasal quadrant. Serial ultrasound examinations of our patients demonstrated development of a large bleb, coincidental with the disturbance in motility. Because of the risk of strabismus, we no longer recommend placing large implant devices in the superior nasal quadrant in eyes that have good vision.

Aged↗