Opioid antagonist-induced modulation of cerebral and hippocampal development: histological and morphometric studies

The role of endogenous opioid systems in preweaning cerebral and hippocampal development was explored in rats utilizing naltrexone, a potent opioid antagonist. Sprague-Dawley rats were given daily injections (s.c.) of either 1 or 50 mg/kg naltrexone to invoke a temporary or complete blockade, respectively, of opioid receptors throughout the first 3 weeks of postnatal life; animals injected with sterile water served as controls. At weaning (Day 21), macroscopic, morphometric, and histological assessments were undertaken. In general, 50 mg/kg naltrexone had a stimulatory action on brain development, whereas 1 mg/kg naltrexone had an inhibitory influence. In most cases, both males and females were affected comparably. Opioid antagonist action was especially directed at cellular and tissue differentiation, with marked changes in macroscopic and areal dimensions and histotypic organization observed in the cerebrum. A prominent effect on the cerebrum of the 1 mg/kg naltrexone group was a substantial increase in packing density of the neural cells, reflecting a reduced area for accommodating neural elements. Changes in the hippocampus were largely restricted to the 1 mg/kg group. However, the number of granule cells was increased in the dentate gyrus of the 50 mg/kg group, suggesting that opioid receptor blockade affects cell types undergoing postnatal proliferation. Cellular elements derived prior to naltrexone treatment (e.g., pyramidal neurons) were capable of being influenced in only differentiative capacity. Our results show that endogenous opioids are natural trophic factors in brain development and provide evidence for the crucial role of endogenous opioid-opioid receptor interaction in neuro-ontogeny.     

ATPase pump site density in human dysfunctional corneal endothelium

Proper corneal hydration is maintained by a Na, K-ATPase pump located in the lateral membranes of the endothelial cells. In dysfunctional corneas this pumping action appears to break down as the corneas become edematous. In order to provide quantitative and qualitative data on the Na, K-ATPase pump site density on dysfunctional and functional human corneal endothelial cells, the present study has employed both autoradiographic and histochemical techniques. Computer-assisted morphometrics and statistical analysis showed that there was a significant reduction (P less than 0.001) in 3H-ouabain binding, and thus ATPase pump sites, in the three types of corneas (Fuchs' endothelial dystrophy, aphakic and pseudophakic bullous keratopathy) with dysfunctional endothelia as compared to both types of corneas (eye bank, keratoconus) with functional endothelial cells. There were no significant differences amongst the dysfunctional types or between the two functional types of corneal endothelial cells in respect to density of silver grains. Histochemical staining for ATPase showed less p-nitro-phenylphosphatase histochemical reaction product present on dysfunctional endothelial lateral membranes than in the functional cells.     

AUTACOID INTERACTIONS IN THE REGULATION OF BLOOD FLOW IN THE HUMAN PLACENTA

1. Interactions between autacoids may play important roles in the regulation of blood flow in the foetal placenta. In order to investigate this aspect of placental haemodynamics, human normal-term placentae were perfused in vitro and the responses of the foetal vessels to various combinations of vasoactive agents were determined. 2. Vasoconstriction responses to 5-hydroxytryptamine (5-HT) were potentiated in the presence of endothelin-1 (ET-1), the thromboxane A₂-mimetic U46619 and a nitric oxide synthase inhibitor, N-nitro-l -arginine (NOLA), but not in the presence of angiotensin II. 3. N-Nitro-l -arginine caused vasoconstriction of the perfused placenta and indomethacin attenuated this effect and blocked the potentiation of the 5-HT response by NOLA. 4. Indomethacin did not affect ET-1-induced pressure increases and infusion of U46619 had no effect on release of ET-Iike immunoreactivity into the foetal placental circulation. 5. The present study provides evidence of interactions between several autacoids in human perfused placentae in vitro. These interactions may play important roles in foetal placental haemodynamics in normal or pathological situations.     

Detection of left atrial myxoma with SPECT cardiac imaging

A 69-year-old man with a left atrial myxoma underwent a gated cardiac blood pool radionuclide study that failed to visualize the cardiac tumor on either the planar images or on the composite cineangiograms from the anterior and 45 degrees LAO projections. A nongated cardiac SPECT examination, however, easily demonstrated the atrial myxoma in its characteristic location, adjacent to the interatrial septum. SPECT dramatically improved the image contrast; provided views in transaxial, coronal, and sagittal planes; and allowed direct comparison with computed tomography. Gated cardiac SPECT may be expected to provide a more accurate analysis of the complex motion and attachment site of these intracardiac tumors, as well as a more accurate tumor volume analysis.     

Parasitism of Coquillettidia perturbans by two water mite species (Acari: Arrenuridae) in Florida

Female Coquillettidia perturbans collected in northern Florida were commonly parasitized by 2 species of water mites. Earlier in the year, mosquitoes were parasitized primarily by Arrenurus danbyensis and later in the year primarily by Arrenurus delawarensis. The number of mosquitoes simultaneously parasitized by both parasites is apparently greater than expected due to chance.     

High rate of prolonged remissions following combined modality therapy for patients with localized low-grade lymphoma

Purpose: Involved field (IF) radiation can cure as many as 40%to 50% of patients with stage I-II low-grade lymphoma. We soughtto improve these results by prospectively evaluating the combinationof IF radiation and chemotherapy consisting of 10 courses ofcyclophosphamide, vincristine, prednisone, and bleomycin, withdoxorubicin added in a risk-adapted manner (COP/CHOP-Bleo). Patients and methods: From 1984 until December 1992, 91 patients,median age 56 years (range 28 to 77 years), with clinical stageI-II low-grade lymphoma were treated. No patients were excludedon the basis of age or organ function. Results: A complete response was attained in 99% of evaluablepatients. Treatment-related toxicity was mild, and no deathsoccurred during therapy. With a median follow-up of 60 months,there have been only 16 relapses. The actuarial freedom fromrelapse rate at five years is 82% (95% confidence interval 71%to 89%) and at 10 years is 73%. At five years the overall survivalrate is 90% (95% confidence interval 81% to 95%) and at tenyears it is 82%. Of the clinical features examined, only olderage (>56 years; p = 0.07) was associated with shorter survival.No features examined were predictive of disease relapse. Conclusion: The combination of IF radiation and risk-adaptedCOP/CHOP-Bleo chemotherapy is well-tolerated, produces a veryhigh rate of complete remission, and with a median follow-upof five years, has produced lower rates of relapse and betteroverall survival than has been reported for IF radiation alonein patients with clinically-staged I-II low-grade lymphoma. combined chemotherapy-radiotherapy, follicular small cleaved cell lymphoma, stage I-II low-grade lymphoma     

Severe anaphylactoid reactions to cuprammonium cellulose hemodialyzers

Twenty-one severe reactions to hemodialysis occurred in approximately 260,000 dialysis treatments at three centers within a 10 1/2-year period. Reactions typically appeared within minutes of initiating dialysis, and were characterized by cardiopulmonary, mucocutaneous, and/or gastrointestinal tract symptoms highly suggestive of anaphylaxis. Four respiratory arrests and one death resulted. Analysis of dialyzer use patterns and of each patient's dialyzer exposure history strongly implicated hollow-fiber dialyzers made of cuprammonium cellulose (CC) as a cause of these reactions. No obvious factors could be found to identify predisposed patients. Less than optimal rinsing of the CC hollow-fiber dialyzers prior to use may have been responsible for some, but not all, of these reactions.     

Induction of an anomalous blue-green wavelength discrimination by reduced viewing time

Wavelength discrimination was studied on three colour-normal human observers for open viewing and for reduced time viewing. All three observers show a loss of blue-green wavelength discrimination when viewing time is reduced to 3.75 msec. This loss is shown to be an effect of viewing time alone and not of reduced retinal illuminance. The results confirm those reported by Foster, Scase and Taylor¹ although the target size and methodology are different.