Compensation for light loss resulting from filtering by macular pigment: relation to the S-cone pathway.

PURPOSE: Macular pigment (MP) filters short-wavelength light before it reaches the visual pigments. At peak absorbance (460 nm), transmission of light through MP can range from almost 100% transmission to as little as 3%. As a result of the uneven topographic distribution of MP, spatial nonuniformities in visual perception would result if the visual system did not compensate for filtering differences across the central retina. This study characterizes compensation for different densities of MP. METHODS: Sixteen young subjects (aged 24-40 years) with a wide range of MP density were studied. Increment thresholds were measured at 440 and 500 nm in the center of the fovea and at 6 degrees to 7 degrees eccentricity using conditions chosen to isolate the pi-1 mechanism. For six of the subjects, increment thresholds were also obtained for eccentricities of 1 degrees , 1.75 degrees , and 3 degrees . MP density was measured using heterochromatic flicker photometry at the same locations as the increment thresholds. RESULTS: Peak sensitivity of the short-wavelength pathway across the central retina was constant despite MP density differences as large as 1.0 log unit. CONCLUSIONS: These results suggest that the visual system increases gain of the S-cone pathway to offset light absorption by MP.     

Effect of chronic oral domperidone therapy on gastrointestinal symptoms and gastric emptying in patients with parkinson's disease

This study investigated whether domperidone could improve gastrointestinal symptoms in patients with Parkinson's disease who were receiving levodopa therapy. A total of 11 patients were studied. Following a baseline gastric emptying test, patients were treated with a starting dose of domperidone 20 mg p.o. q.i.d. A follow-up gastric emptying test was repeated at least 4 months after starting domperidone therapy. At the beginning and at each 3-month follow-up visit, symptoms of nausea, vomiting, anorexia, abdominal bloating, heartburn, regurgitation, dysphagia, and constipation were evaluated and scored on a scale of 0–3. The overall mean follow-up period was 3 years. Compared with their baseline evaluation, patients experienced a significant improvement in all symptoms (p < 0.05) except dysphagia and constipation. Gastric emptying of an isotope-labeled solid meal was significantly faster, with a baseline result of 60.2 ± 6.4% retention of isotope 2 h after the meal compared with 37.0 ± 2.2% retention during domperidone therapy (p < 0.05). Patients' global assessment of Parkinson's disease remained stable or improved. Serum prolactin was elevated in all patients after domperidone therapy (p < 0.05). Domperidone therapy significantly reduces upper gastrointestinal symptoms and accelerates gastric emptying of a solid meal, but does not interfere with response to antiparkinsonism treatment.     

Dopamine denervation does not alter in vivo 3H-spiperone binding in rat striatum: implications for external imaging of dopamine receptors in Parkinson's disease

Striatal particulate preparations, both from rats with lesion-induced striatal dopamine (DA) loss and from some striatal dopamine (DA) loss and from some patients with Parkinson's disease, exhibit increased 3H-neuroleptic binding, which is interpreted to be the mechanism of denervation-induced behavioral supersensitivity to dopaminergic compounds. After intravenous 3H-spiperone (3H-SP) administration to rats with unilateral nigral lesions, we found no differences in accumulation of total or particulate-bound 3H-SP in dopamine-denervated compared with intact striata. 3H-SP in vivo binds to less than 10% of striatal sites labeled by 3H-SP incubated with striatal particulate preparations in vitro. Quantitative autoradiography of 3H-SP binding to striatal sections in vitro also failed to reveal any effects of dopamine denervation. 3H-SP bound to striatal sites in vivo dissociates more slowly than that bound to striatal particulate preparations labeled in vitro. Striatal binding properties of 3H-SP administered in vivo are quite different from the same kinetic binding parameters estimated in vitro using crude membrane preparations of striatum. In addition, striatal binding of in vivo-administered 3H-SP is not affected by prior lesion of the substantia nigra, which results in profound ipsilateral striatal dopamine depletion. Thus, behavioral supersensitivity to dopaminergic compounds may not be associated with altered striatal binding properties for dopamine receptor ligands in vivo.     

Fever and feeding in the rat: Actions of intrahypothalamic interleukin-6 compared to macrophage inflammatory protein-1β (MIP-1β)

The chemokines, macrophage inflammatory protein-1 (MIP-1) and its subunit MIP-1β, induce an intense fever in the rat when they are injected directly into the anterior hypothalamic, pre-optic area (AH/POA), a region containing thermosensitive neurons. The purpose of this study was to compare the central action on body temperature (T_b) of MIP-1β with that of interleukin-6 (IL-6), which also has been implicated in the cerebral mechanism underlying the pathogenesis of fever. Following the stereotaxic implantation in the AH/POA of guide cannulae for repeated micro-injections, radio transmitters which monitor T_b continuously were inserted intraperitoneally in each of 15 male Sprague-Dawley rats. Each micro-injection was made in a site in the AH/POA in a volume of 1.0 μl of pyrogen-free artificial CSF, recombinant murine MIP-1β, or recombinant human IL-6. MIP-1β in a dose of 25 pg evoked an intense fever characterized by a short latency, a mean maximum rise in T_b of 2.4 ± 0.21°C reached by 3.7 ± 0.42 hr, and a duration exceeding 6.5 hr. Injected into homologous sites in the AH/POA, IL-6 induced a dose dependent fever of similar latency and a mean maximal increase in T_b of 1.2 ± 0.25°C, 1.8 ± 0.15°C, and 2.1 ± 0.22°C and duration of 6.2 ± 1.28 hr, 6.7 ± 0.49 hr, and 6.8 ± 0.65 hr when given in doses of 25, 50, and 100 ng, respectively. These results show that MIP-1β and the highest dose of IL-6 induce a fever of comparable intensity, but MIP-1β exerts its action in a much lower concentration. Thus, the de novo synthesis and subsequent action of the MIP-1 family of cytokines on neurons of the AH/POA in response to a pyrogen challenge apparently play a functional role in the pathogenesis of fever. Further, the endogenous activity of IL-6 in the hypothalamus which is enhanced in response to a lipopolysaccharide also may reflect its essential part in the acute phase response to a bacterial challenge. Copyright © 1994 Wiley-Liss, Inc.     

Common bile duct calculi: updated experience with dissolution with methyl tertiary butyl ether

The authors describe their experience with methyl tertiary butyl ether (MTBE) in a larger series of patients than previously reported in order to acquaint physicians with both its effectiveness for dissolution of common bile duct calculi and the limitations of its use. Ten patients with 13 biliary calculi underwent percutaneous stone dissolution treatment with the experimental cholesterol solvent, MTBE. Three stones completely dissolved within 30 minutes, seven were reduced in size, and three were visibly unaffected. All stones not completely dissolved were easily extracted by means of a stone basket except for one in a patient taken to surgery. Although MTBE perfusion is an effective technique for management of biliary calculi, practitioners should be aware that its use is quite time consuming and its odor difficult to control.     

Expression of cadherins and CD44 isoforms in ovarian endometrial cysts

We evaluated the immunohistochemical expression of cadherins and CD44 variants in 20 endometriomas, 20 cystadenomas, 20 borderline ovarian tumours as well as 20 ovarian carcinomas, and the serological and cystic fluid concentrations of soluble E-cadherin and soluble CD44 standard (sCD44sdt) in 20 endometriomas, 20 cystadenomas, six borderline and 11 carcinomas of the ovary. In endometriomas, immunostaining of E- and N-cadherin was negative (20 and 30% respectively). CD44 H, v3 and v6 immunostaining were detected in 63, 10 and 40% respectively. A difference in immunostaining for E-cadherin was found between endometriomas and cystadenomas (P < 0.001) and for N- cadherin between endometriomas and carcinomas (P < 0.001). A difference in CD44H immunostaining was observed between endometriomas and cystadenomas (P < 0.035) but not with borderline ovarian tumours and carcinomas. No difference in serum concentrations of soluble E- cadherins and CD44 standard was found between the four groups of tumours. Cystic fluid concentrations of E-cadherin were lower in endometriomas than in borderline tumours and ovarian carcinomas (P < 0.001). High concentrations of soluble CD44 standard cystic fluid were found in endometriomas than in other ovarian cysts. Endometriomas and borderline tumours share alterations of cadherins and CD44 isoforms which may help in the understanding of the aggressive and invasive potentials of endometriotic cells.      

Genital asymmetry in men

This study examined genital asymmetry in a large sample of men. The probands were 6544 non-delinquent men who were interviewed by the Kinsey Institute for Research in Sex, Gender and Reproduction from 1938 to 1963. The measures were four indicators of penile and scrotal asymmetry, along with self-reported handedness, from Kinsey's interview protocol. Most men reported some degree of lateral asymmetry in their flaccid penis and in their testicles; less asymmetry was reported for their erect penis. The asymmetry typically occurred in the left direction, and this pattern occurred in both right- and nonright- handers. However, this 'leftward' pattern was significantly less pronounced in nonright-handers. The results are discussed in relation to previous findings of genital asymmetry in men, the possible relationship of genital asymmetry to functional cerebral asymmetry, and recent data suggesting genital asymmetry may predict patterns of cognitive performance and genital/sexual organ cancers.      

A novel DRB1 allele in DR2-positive American blacks

Class II D region antigens of the major histocompatibility complex are naturally occurring dimeric proteins found on the surface of lymphoid cells. In most haplotypes at least two of the polymorphic beta chains are associated with a nonpolymorphic alpha chain. The allelic variation of these proteins lies in the first domain of the expressed protein. At present, there are four known DRB genes. DRB1 encodes for the classical DR 1, 3, 4, 5, etc., specificities. DRB3 and DRB4 encode the four supertypic specificities of DRw52 and the single phenotype of DRw53, respectively. Two DRB genes are expressed in human leukocyte antigen DR2-positive individuals. While DRB1 is the more polymorphic gene in most haplotypes, in DR2 haplotypes it appears that DRB5 encodes the polymorphic DR beta chain and the DRB1 encodes a nonpolymorphic beta chain. We attempted to further define the diversity of this region by direct dideoxynucleotide sequencing of polymerase-chain-reaction-amplified genomic DNA. We identified a novel DRB1 allele in DR2-positive individuals that was only observed in the American blacks sampled. This allele may code for a black specific class II antigen.