Inhibitory influence of unstimulated rods in the human retina: evidence provided by examining cone flicker.

In the parafoveal retina of human observers, cone-mediated sensitivity to flicker decreases as rods become progressively more dark-adapted. This effect is greatest when a rod response to flicker is precluded. These results indicate that rods tonically inhibit cone pathways in the dark.

Expression pattern of CXCR3, CXCR4, and CCR3 chemokine receptors in the developing human brain.

Chemokine receptors are essential components of the immune and central nervous systems, but little is known about their distribution during development. We evaluated the distribution of 3 chemokine receptors: CXCR3, CXCR4, and CCR3 in the human developing brain. Of these, CXCR3 was the only receptor expressed in fetal brain at 26 wk of gestation and its expression was restricted to glial cells, endothelial cells, and the choroid plexus. Neuronal staining was only seen at term in the Purkinje cells of the cerebellum. CCR3 appeared only at term in both neurons and glial cells. The expression pattern of these 2 receptors in the late gestation and term resembled that of adults. CXCR4 could not be detected in the fetal brain on neurons nor on glial cells. By examining pediatric cases, we determined that CXCR4 expression commences sometimes between 3.5 and 4.5 yr. Two of the chemokine receptors examined, CCR3 and CXCR4, can be used as co-receptor together with CD4 for HIV entry, but neither was expressed during the second trimester of pregnancy. Our findings suggest that it is unlikely that CCR3 or CXCR4 play a major role in HIV-1 transmission in the fetal brain before 37 wk of gestation.

Patient-related variables and restenosis after percutaneous transluminal coronary angioplasty--a report from the M-HEART Group.

As part of a randomized prospective study designed to investigate the restenosis process after percutaneous transluminal coronary angioplasty (PTCA), the relation between patient-related variables and restenosis rate was examined. A total of 722 patients had successful PTCA. Angiographic follow-up was scheduled for 6 +/- 2 months after the procedure and achieved in 510 patients (71%), yielding 598 lesions for analysis. The overall restenosis rate was 40%. The rate was higher in patients undergoing early restudy for a clinical event than in those undergoing routinely scheduled follow-up restudy (71 vs 22%, p less than 0.0001). Age, sex, cigarette smoking history, diabetes mellitus and history of previous myocardial infarction were not associated with restenosis rate. Angina duration and severity before PTCA were also unrelated to restenosis rate. In summary, these variables, many of which have been previously implicated in restenosis, were not found to be predictors of restenosis. The decision to perform PTCA in individual patients should not be negatively influenced by the presence of these factors.

Traumatic intraconal hematic cyst of the orbit.

A 35-year-old man with a history of repeated previous facial injuries presented with acute onset of a right orbital mass less than 2 weeks after blunt trauma to the right eye. Orbital B-scan ultrasonography and computed tomography showed an intraconal cystic lesion. The tumor was excised via lateral orbitotomy. Pathologic evaluation demonstrated a hematic cyst containing fresh blood. The presence of hemosiderin in the cyst wall suggested recent bleeding in a preexisting orbital hemorrhagic lesion. Patients with hematic cysts of the orbit usually present with a subperiosteal mass months to years after trauma.

Poorly differentiated primary orbital sarcoma (presumed malignant rhabdoid tumor). Radiologic and histopathologic correlation.

A 47-year-old man presented with acquired hyperopia and gaze-evoked visual loss. Computed tomography and magnetic resonance imaging demonstrated a well-circumscribed intraconal tumor. Histopathologic studies indicated that the tumor was a poorly differentiated primary orbital sarcoma compatible with malignant fibrous histiocytoma or malignant rhabdoid tumor. To our knowledge, no case of primary orbital malignant rhabdoid tumor has been previously described in an adult.

Primary orbital neuroblastoma.

A 35-year-old man had a primary neuroblastoma of the left orbit. Histopathologically, the tumor was composed of uniform small round cells containing argyrophilic granules arranged in nests and cords with pseudorosettes, Homer-Wright rosettes, and a fine fibrillary background matrix. Immunohistochemical staining for chromogranin was positive. Electron microscopy showed small (108- to 173-nm) dense core granules. Eight years after surgery and radiation therapy the patient was free of local recurrence and metastases. To our knowledge, primary orbital neuroblastoma has been reported only once previously. Neuroblastoma, which occurs most frequently in children and has an incidence in the United States of 500 cases annually, is a distinctly unusual tumor in adults.

The influence of cone adaptation upon rod mediated flicker.

The influence of annular fields on sensitivity to sinusoidal flicker was assessed in the dark adapted parafoveal retina. Test stimuli were 2 degrees 20' in diameter; annuli had a 2 degrees 20' inner and 7 degrees 30' outer diameter. Rod flicker was studied with a "green" stimulus too dim to influence cones. Selective cone flicker was obtained using red and green flicker in counterphase and yoked together in modulation depth and scotopic illuminance. Results showed the following. (1) Annular stimulation of rods slightly facilitated rod-mediated flicker sensitivity to frequencies less than 10 Hz. In contrast, annular stimulation of cones greatly facilitated rod-mediated sensitivity, particularly for flicker frequencies greater than 7 Hz. We designate this effect, cone-rod interaction. (2) Annular stimulation of cones has a negligible influence upon sensitivity to cone-mediated flicker frequencies less than 15 Hz. In contrast, annular stimulation of rods has a large influence upon sensitivity to cone-mediated flicker, an effect we designate rod-cone interaction. (3) Within limits, both rod-cone and cone-rod interaction increase as the annular illuminance increases and as flicker frequency increases; the limiting frequency and illuminance values, however, are different for the two forms of interaction. Results are compared with prior evidence that rod and cone signals summate to produce an absolute threshold or flicker sensation. We suggest that there are at least three mechanisms for interaction between rod- and cone-related signals.

Herpes simplex blepharoconjunctivitis presenting as complete acquired ankyloblepharon.

PURPOSE: A 90-year-old woman was referred to us with a 1-month history of progressively worsening blepharoconjunctivitis. She had a complete acquired ankyloblepharon of the right lids, which resulted in the appearance of a right upper lid abscess on computed tomography. METHODS: Blepharotomy with separation and debridement of the lid margins was performed. RESULTS: Cultures were positive only for herpes simplex virus, type II. CONCLUSIONS: Herpes simplex blepharoconjunctivitis may take many clinical forms. Our patient's severe manifestations led to the clinical and radiologic appearance of preseptal cellulitis with a right upper lid abscess.

Blistering diseases. Diagnostic help for primary care physicians.

At presentation, the differential diagnosis of bullous disease may seem difficult. However, the diagnosis may be clarified by considering such factors as Nikolsky's sign, age of the patient at onset, and pattern and distribution of blisters. Careful review of family, recreational, occupational, and drug histories may also help to identify the cause.

Patients' theories of pathogenesis.

Certain patients embark upon analytic treatment with well thought out theories regarding the origins of their difficulties. Although there is always some validity to such theories, they turn out to be incomplete and serve to screen painful recollections and pathogenic unconscious wishes and the defenses against them. Two cases are presented to illustrate how analysands use these theories in the service of resistance. Painstaking analytic work is required to elucidate their defensive nature. The narcissistic importance of such theories in maintaining a coherent narrative about one's life in the face of uncertainty is discussed, and technical and countertransference considerations are explored.

The evolution of patients' theories of pathogenesis.

The author views the patient's theory of pathogenesis as a compromise formation to which both patient and analyst contribute in important ways. Unlike conventional autobiography or case histories, the patient's theory of pathogenesis is an ever-evolving product of the analytic collaboration that is subject to ongoing analysis and self-inquiry. Like any explanatory theory, it both opens and constrains interpretive possibilities. The collaborative attempt to arrive at the best possible explanatory narratives entails both uncovering and joint construction. Explanatory efforts that are anchored in consensually agreed-upon present experiences of resistances and transferences are more closely related to therapeutic action and are more likely to be verifiable than explanatory theories tied to distant past events. The open-ended nature of the life historical and explanatory narratives leads to an emphasis on continued self-analytic activities after termination.

Managing Year 2000 risks within health care systems.

With every kind of health care provider turning to computers for efficiency and to enable smooth transactions with other providers, it is time--and beyond time--to ensure that these networks and tools will continue to function when the year 2000 rolls around. Much media attention has focused on this Year 2000 problem; what does it mean for home care providers?