Axial length in keratoconus.

Axial length is a major determinant of ocular refractive power that has not been well established for keratoconus eyes. The purpose of this study was to establish the mean and range of axial length among both keratoconus eyes with no previous surgery and postkeratoplasty keratoconus eyes, and to determine if there is a significant reduction of axial length following variations in surgical techniques in penetrating keratoplasty. The axial length of 157 keratoconus eyes with no previous surgery was measured using applanation ultrasonography. The mean axial length measurement was 24.39 (+/- 1.13 mm), with a range of 21.82-28.69 mm. The axial length of 66 postkeratoplasty keratoconus eyes was similarly measured. The mean axial length measurement was 24.10 (+/- 1.22 mm), with a range of 21.83-26.87 mm. These values are not significantly different from the axial length mean and range found among emmetropic eyes. A significant shortening of the axial length (F = 5.2, p = 0.04) was obtained in the postoperative penetrating keratoplasty eye if the donor trephine was 0.3 mm smaller in diameter than the recipient trephine. The axial length of individual keratoconus eyes is a major factor in determining postoperative refractive error. It therefore becomes important when considering variations in surgical procedures to reduce postoperative myopia.

Nontuberculous mycobacterial keratitis. Report of two cases and review of the literature.

We report two cases of nontuberculous mycobacterial keratitis. To our knowledge, case 1 is the first documented case of Mycobacterium chelonei sclerokeratitis and case 2 is the first report of Mycobacterium flavescens keratitis. A total of 40 cases of nontuberculous mycobacterial keratitis involving at least five different species have been reported previously in the literature. Almost all of these opportunistic infections have occurred following either accidental or surgical ocular trauma, usually associated with the use of local corticosteroids. Encountered infrequently, these organisms can be incorrectly identified as other bacteria, including diphtheroids and Nocardia species. Histopathologic examination and special stains of infected tissues may be helpful in establishing the correct diagnosis. Cultures and sensitivity testing are mandatory in determining appropriate treatment.

Beta-endorphin blunts phosphatidylinositol formation during in vitro activation of isolated human lymphocytes: preliminary report.

We have previously described the regulatory effect of beta-endorphin on three human cytotoxic cell populations. We confirmed the variable nature of these effects on human natural killer cell (NK) activity, showed mixed effects on the generation of cytotoxic T lymphocyte (CTL) activity, and demonstrated the reproducible suppression of lymphokine-activated killer cell (LAK) activity. We and others also observed mixed effects of beta-endorphin on the proliferative response to mitogens and in mixed leukocyte reactions. In the study reported here, we test the effects of beta-endorphin on the formation of phosphatidylinositol during cell activation. 32P-radiolabeled peripheral blood mononuclear cells obtained from normal adult donors and CD2-depleted subpopulations were activated with phytohemagglutinin or in a NK, LAK, or CTL protocol in the absence or presence of recombinant beta-endorphin. The total lipidic extract was analyzed by thin-layer chromatography and autoradiography. The results of these studies indicate that beta-endorphin blunts the formation of phosphatidylinositol by about 20% in the four systems studied and in all the donors tested. This effect is dose-dependent and is blocked in part by the opioid antagonist, naltrexone, suggesting involvement of the opioid receptor.

Differential effect of beta-endorphin on three human cytotoxic cell populations.

We have examined in vitro the effect of the proopiomelanocortin gene product, beta-endorphin (bE), on the cytotoxic activity of natural killer (NK) cells, lymphokine activated killer (LAK) cells and cytotoxic T-lymphocytes (CTL). Our studies show that bE reproducibly suppressed LAK cytotoxic activity in all donors tested. The effect of bE on the generation of CTL varied, and was negligible on CTL cytotoxic function. Our study also confirms the variable nature of the effects of bE on NK cytotoxicity. In all instances, the effects of bE were generally small, but could be blocked by opioid receptor antagonists, or by prior heat-inactivation of the peptide. The magnitude of the effects was greatest at low effector:target ratios in all of the three systems studied. These results support the emerging body of evidence that the neuroendocrine system may influence host defense mechanisms mediated by cytotoxic cells.

Equivalent helper functions of human "naive" and "memory" CD4+ T cells for the generation of alloreactive cytotoxic T lymphocytes.

Cells comprising the CD4+ T-cell population are heterogeneous with regard to function, maturation, and the expression of membrane molecules such as the CD45RA antigen. Previous analyses of the CD4+ subsets defined by CD45RA antigen expression have shown that the ability to provide help for antibody production is restricted to cells within the CD4+CD45RA- subset. In the present studies, we have examined the ability of "naive" CD4+CD45RA+ cells and "memory" CD4+CD45RA- cells to provide help for the generation of alloreactive CD8+ cytotoxic T lymphocytes. When purified CD4+CD45RA+ or CD4+CD45RA- cells were cultured with autologous CD8+ cells and allogeneic E- stimulator cells, both subsets were consistently able to provide help for CD8+ cytotoxic T-cell development. In contrast, the ability to provide help for antibody production was restricted to cells in the CD4+CD45RA- subset. Differences in the mechanisms of the helper functions for these two systems were also identified. Whereas exogenous interleukin-2 (IL-2) could replace the help provided by either CD4+ subset for cytotoxic T-cell generation, IL-2 had only minimal effects on immunoglobulin production. Thus, our studies highlight the contrasting cellular requirements and mechanisms involved in "help" for B-cell differentiation versus cytotoxic T-lymphocyte generation, and they show that the helper/inducer functions of human CD4+ cells are not mediated solely by the CD4+CD45RA- subset.

Limb leads of the electrocardiogram: sequencing revisited.

The six limb leads are normally presented in a format the logic of which is traditional rather than anatomical and does not allow visual interpolation such as is customary with the six chest leads. The sequence: a VL, I, -aVR, II, aVF, III was suggested years ago, and is used in some European countries, particularly Sweden. It provides a better impression of the extent of the changes of inferior infarction and makes the rather neglected lead aVR much more useful, though reversed in polarity. It also provides a more direct indication of the electrical axis, and simplifies comparisons with the frontal plane vectorcardiogram. Because modern digital electrocardiographs can provide the sequenced format, this seems a good time to review the advantages of adopting it.

Coxsackie B5 heart disease. Demonstration of inferolateral wall myocardial necrosis.

A case of Coxsackie B5 viral myopericarditis is presented in which the diagnosis of inferolateral wall myocardial necrosis was made on the basis of specific cardiac enzyme changes and radionuclide myocardial imaging. This localized damage may have resulted from coronary arteritis with resulting infarction or necrosis secondary to preferential viral involvement of the inferolateral wall of the myocardium. Hepatitis and cerebral embolism complicated the case, with the latter suggesting endocardial disease.