The treatment of choroidal neovascular membranes by alpha interferon. An efficacy and toxicity study

PURPOSE

The purpose of this phase 2 study was to determine the potential efficacy and safety of systemic alpha interferon in the treatment of subfoveal choroidal neovascularization associated with age-related macular degeneration or ocular histoplasmosis.

METHOD

Subcutaneous alpha interferon was administered to 24 patients (24 eyes), and they were prospectively studied. Alpha interferon was administered subcutaneously four times daily at a dose of 3 x 10(6) U/m2 (average total dose, 204 MU). The studied parameters included best-corrected visual acuity, membrane size, blood, exudates, and subretinal fluid. Toxic effects and performance status were graded according to the National Cancer Institute toxicity criteria and Karnofsky performance scale, respectively.

RESULTS

Of the 24 treated eyes, 5 (21%) showed objective evidence of anatomic improvement, as defined by decrease in membrane size or improvement in fluorescein angiographic characteristics, but in only 3 of these 5 was the improvement maintained. The same three patients achieved and maintained functional success (visual improvement). Two of the five patients with initial anatomic improvement had subsequent membrane recurrence, which resulted in no visual change in one but visual loss in the other. For the majority of patients, the anatomic and visual status remained the same or became worse after treatment. All patients experienced some degree of adverse reactions involving multiple organ systems. Decreased performance status affected 80% of the patients.

CONCLUSION

This study documents that regression of choroidal neovascularization that occurred with alpha interferon treatment was minimal. Toxic effects interfering with patients' performance status are associated with alpha interferon treatment. Although a randomized trial of interferon versus no therapy may be warranted, fundamental issues (i.e., the biologic properties of interferon versus other more potent agents against choroidal neovascularization, medication dosages, and routes of administration), need to be addressed before embarking on such a trial.

Fast events in protein folding initiated by nanosecond laser photolysis

Initiation of protein folding by light can dramatically improve the time resolution of kinetic studies. Here we present an example of an optically triggered folding reaction by using nanosecond photodissociation of the heme-carbon monoxide complex of reduced cytochrome c. The optical trigger is based on the observation that under destabilizing conditions cytochrome c can be unfolded by preferential binding of carbon monoxide to the covalently attached heme group in the unfolded state. Photodissociation of the carbon monoxide thus triggers the folding reaction. We used time-resolved absorption spectroscopy to monitor binding at the heme. Before folding begins we observe transient binding of both nonnative and native ligands from the unfolded polypeptide on a microsecond time scale. Kinetic modeling suggests that the intramolecular binding of methionine-65 and -80 is faster than that of histidine-26 and -33, even though the histidines are closer to the heme. This optical trigger should provide a powerful method for studying chain collapse and secondary structure formation in cytochrome c without any limitations in time resolution.

Regulation of tyrosine phosphorylation in neutrophils by the NADPH oxidase. Role of reactive oxygen intermediates

Neutrophils possess a multicomponent NADPH-oxidase that produces large quantities of superoxide, which can in turn generate other reactive oxygen intermediates. Superoxide and its dismutation product, hydrogen peroxide, are powerful oxidants. Because the activity of certain tyrosine kinases and phosphatases can be affected by their redox state, we considered the possibility that endogenously generated reactive oxygen intermediates (ROI) may alter phosphotyrosine formation and thereby function as intra- or intercellular messengers in neutrophils. Exposure of human neutrophils to exogenous oxidants such as diamide induced marked tyrosine phosphorylation of several cellular proteins. More importantly, activation of the NADPH oxidase in permeabilized neutrophils, by direct stimulation of GTP-binding proteins, also resulted in enhanced tyrosine phosphorylation. The latter was NADPH-dependent, paralleled by production of superoxide, and was inhibited by diphenylene iodonium, an inhibitor of the flavoprotein component of the oxidase. Neutrophils, from a patient with chronic granulomatous disease, which are deficient in the production of ROI, demonstrated no such phosphotyrosine accumulation. We conclude that ROI produced by the NADPH oxidase can regulate tyrosine phosphorylation in granulocytes, possibly by effects of oxidation-sensitive tyrosine kinases and/or phosphatases.

Cyclosporine as possible prophylaxis for obstructive airways disease after allogeneic bone marrow transplantation

The objective of this study was to evaluate the impact of cyclosporine (cyclosporin A; CyA) prophylaxis for graft-versus-host disease (GVHD) on the development of obstructive airways disease (OAD) after allogeneic bone marrow transplantation (BMT) in leukemic patients. Patients with normal pulmonary function tests (PFTs) prior to BMT were followed with serial PFTs for the development of OAD. Follow-up PFTs were performed at 3, 6, 9, and 12 months, and thereafter at consecutive yearly intervals. Obstructive airways disease was defined as FEV1 less than 80 percent, ratio of FEV1 over the forced vital capacity (FEV1/FVC) less than 80 percent of predicted, maximal midexpiratory flow rate at 50 percent vital capacity less than 65 percent of predicted, or residual volume greater than 120 percent of predicted. In the period prior to CyA prophylaxis for GVHD development (March 1983 to September 1986), 17 (39 percent) of the 44 patients undergoing BMT developed OAD, compared with 2 (4 percent) of 45 in the post-CyA period (September 1986 to March 1990) (chi 2 = 17; p < 0.00005). Age, sex, type of leukemia, severity of GVHD, histocompatibility status, presence of acute GVHD, and sex mismatch between donor and recipient were not associated with development of OAD. Although chronic GVHD was associated with OAD in univariate analysis, a multivariate logistic regression analysis showed that the only significant independent predictor for OAD was the use of CyA. We conclude that CyA is protective against the development of OAD after BMT in leukemic patients.

Handedness and sleep apnea

Left-handedness is associated with shorter life span. Many of the factors contributing to this higher mortality (eg, alcohol consumption, automobile accident, smoking) are the same as in patients with sleep apnea, who also have higher mortality than nonapneic controls. The authors hypothesized that (1) there is a higher prevalence of sinistrality in patients suspected of having sleep apnea than in the general population, and (2) left-handed persons with sleep apnea have a more severe disorder than right-handed ones. These hypotheses were tested in a prospective cohort of 970 patients referred to a sleep disorders center because of suspected sleep apnea. All patients underwent nocturnal polysomnography and measurements of blood pressure. Sixty-one patients were left-handed. The distribution of handedness as a function of age in this cohort was similar to that in the general population. There were 486 patients with an apnea/hypopnea index greater than 10; of these, 34 were left-handed, and 452 were right-handed. Oxygen saturation, blood pressure, age, smoking history, and body mass index were similar in both groups. Left-handed patients with sleep apnea had a significantly higher respiratory disturbance index (RDI) than the right-handed ones (52 +/- 30 vs 38 +/- 35 [p < 0.005]). Right-handed patients were distributed equally among RDI quartiles, but 41 percent of the left-handed patients were within the highest RDI quartile, compared to 12 percent within the lowest quartile. Sinistrality appears to be associated with more severe sleep apnea, which may help to explain the higher mortality seen among the left-handed persons.

Okadaic acid-induced actin assembly in neutrophils: role of protein phosphatases

Activation of neutrophils results in morphological and functional alterations including changes in cell shape and initiation of motile behavior that depend on assembly and reorganization of the actin cytoskeleton. Phosphoproteins are thought to be key intermediates in the regulation of cytoskeletal alterations and whereas much attention has been directed at the role of protein kinases, relatively little information is available on the importance of phosphatases. To elucidate the role of protein phosphatases, we studied the effects of the phosphatase inhibitors okadaic acid and calyculin A on the actin cytoskeleton of human neutrophils. Exposure of cells to okadaic acid resulted in assembly and spatial redistribution of actin, which peaked at 25 min and returned to baseline levels by 45 min, as assessed by flow cytometric analysis of NBD-phallacidin stained cells and confocal fluorescence microscopy, respectively. These effects correlated with an increase in protein phosphorylation, determined by incorporation of 32P into cellular proteins using SDS-PAGE and autoradiography. Similar but more rapid responses were observed in electropermeabilized cells treated with okadaic acid or calyculin A. The dose dependence of these effects was compatible with a role for phosphatase type 1 as the target enzyme. These findings also suggested the presence of constitutively active protein kinases capable of effecting actin polymerization. Phosphorylation of myosin light chain (MLC) has been postulated to promote actin assembly, but myosin light chain kinase (MLCK) appeared not to be involved because: (1) the effect of okadaic acid was not inhibited by the MLCK inhibitor KT5926 and (2) in permeabilized cells suspended in medium with free calcium [Ca2+] < 10 nM (conditions under which MLCK is inactive), the effect of okadaic acid persisted. The role of phosphatases in stimulus-induced actin assembly was assessed in cells preincubated with okadaic acid for 45 min, after F-actin levels had returned to baseline. Under these conditions, okadaic acid completely abrogated actin assembly induced by phorbol myristate acetate, platelet activating factor, and leukotriene B4, whereas the effects of the chemotactic peptide fMLP and opsonized zymosan (OpZ) were unaffected. We conclude that serine and threonine phosphatases exert a tonic negative influence on actin assembly and organization. Furthermore, divergent pathways seem to mediate the response to lipidic stimuli, on one hand, and fMLP and OpZ, on the other, as evidenced by the differential susceptibility to inhibition by okadaic acid.

Treatment of community-acquired pneumonia. A multicenter, double-blind, randomized study comparing clarithromycin with erythromycin. Canada-Sweden Clarithromycin-Pneumonia Study Group

The efficacy and safety of orally administered clarithromycin and erythromycin in the treatment of community-acquired pneumonia were assessed in a multicenter, double-blind, randomized study. Two hundred sixty-eight patients were randomized to receive either clarithromycin, 250 mg twice a day, or erythromycin stearate, 500 mg 4 times a day, for 7 to 14 days. Efficacy was evaluable in 173 patients (92 for clarithromycin, 81 for erythromycin). No statistically significant difference in clinical success rate (cure or improvement) was observed between the two groups (clarithromycin, 97 percent; erythromycin, 96 percent). Both groups had identical radiologic response (97 percent with resolution or improvement). Similarly, no statistically significant difference in bacteriologic response toward the target pathogens was observed among evaluable patients (clarithromycin, 23/26; erythromycin, 17/17; p value = 0.287). Clinical response toward Mycoplasma and Chlamydia pneumonia was comparable between the two groups (clarithromycin, 15/16; erythromycin, 10/11). However, patients receiving erythromycin had a twofold higher incidence of adverse events, mostly related to the gastrointestinal system, and were five times more likely to withdraw from therapy because of drug-related adverse events. These results show that clarithromycin is as effective as erythromycin in the outpatient treatment of community-acquired pneumonia. Furthermore, the lower incidence of adverse events associated with clarithromycin indicates that it is more acceptable to patients and, therefore, can enhance compliance.

Changes in hospital admissions pattern in patients with human immunodeficiency virus infection in the era of Pneumocystis carinii prophylaxis

BACKGROUND

Pneumocystis carinii pneumonia (PCP) was the leading cause of hospital admissions in patients with human immunodeficiency virus (HIV) infection before the widespread use of PCP prophylaxis. We studied retrospectively the changes in annual hospital admission patterns after the start of a population-based PCP prophylaxis program in Toronto. The purpose of the study was to identify the cogent diseases requiring hospitalization of HIV patients in the current era of PCP prophylaxis. This information is important for the allocation of health care resources in the future as well as for targeting research in the prevention of specific HIV-related diseases.

METHODS

The annual HIV-related hospital admissions before and after the start of the Toronto aerosol pentamidine program (May 1989) were studied. All admission records due to AIDS-defining illnesses or occurring in patients with known HIV status in three major referral centers were reviewed. The two periods for comparison were May 1988 through April 1989 and May 1989 through April 1990. The data obtained were stratified according to the following: (1) cause of the illness prompting hospital admission; (2) PCP admissions; and (3) admissions according to the major organ system involved. These categoric data were compared by nonparametric chi 2 tests.

RESULTS AND CONCLUSIONS

Population-based prophylaxis of PCP with aerosol pentamidine resulted in a significant reduction in the total number of PCP hospital admissions. Infection remains the principal cause of hospital admission in HIV patients after the start of the PCP prophylaxis program. However, there was an increase in the proportion of hospital admissions due to nonrespiratory-related infections. There was also a modest increase in admissions due to neurologic and gastrointestinal diseases. Central nervous system lymphoma and cytomegalovirus retinitis accounted for the majority of the rise in the nervous system. These data suggest there is a changing pattern of the diseases leading to the hospitalization of patients with HIV infection in the era of PCP prophylaxis.

Simulations of the temperature dependence of energy transfer in the PSI core antenna

In order to understand the organization of the PSI core antenna and to interpret results obtained from studies of the temperature and wavelength dependence of energy transfer and trapping in the PSI particles, we have constructed a model for PSI in which spectral heterogeneity is considered via a self-consistent approach based on Forster transport. The temperature dependence of the absorption and emission spectra of the individual Chl molecules in the protein matrix is calculated based on a model Hamiltonian which includes a phonon contribution. Time and wavelength resolved kinetics of PSI at different temperatures are investigated by means of two-dimensional lattice models. We conclude that wavelength-dependent fluorescence decay kinetics result only when two or more bottlenecks exist in the energy transfer and trapping process. A single trap or several pseudo-traps with spectrally identical environments do not lead to wavelength dependent decays. Simple funnel arrangements of the spectral types can be ruled out. At least one pigment with energy lower than the photochemical trap located close to the reaction center is required to produce the trends of the fluorescence lifetimes observed experimentally. The remainder of the core antenna is consistent with a random arrangement of spectral types.

Long-term sequelae after recovery from cytomegalovirus pneumonia in allogeneic bone marrow transplant recipients

The clinical course of cytomegalovirus (CMV) pneumonia in seven consecutive bone marrow transplant (BMT) recipients during a 24-month period was studied. Retrospective analysis of clinical data on the recipients with CMV pneumonia during the illness and prospective follow-up of those who recovered from the pneumonia was performed. Those who had CMV as the sole pathogen and with lymphocytosis in the BAL or the peripheral blood during the illness recovered from the pneumonia. On the contrary, those who had mixed bacterial or fungal infection with peripheral lymphopenia died. Persistent lymphocytosis in the BAL and the peripheral blood, in the absence of CMV infection, was observed in the survivors. Two subsequently developed restrictive lung disease and two had relapse of their primary malignancy. These data suggest that CMV pneumonia in BMT patients is associated with significant long-term sequelae. The phenomenon of persistent lymphocytosis in the BAL and the peripheral blood, in the absence of CMV infection, supports Grundy's hypothesis that CMV pneumonia in BMT recipients is an immunopathologic condition.

Phorbol ester-induced actin assembly in neutrophils: role of protein kinase C

The shape changes and membrane ruffling that accompany neutrophil activation are dependent on the assembly and reorganization of the actin cytoskeleton, the molecular basis of which remains to be clarified. A role of protein kinase C (PKC) has been postulated because neutrophil activation, with the attendant shape and membrane ruffling changes, can be initiated by phorbol esters, known activators of PKC. It has become apparent, however, that multiple isoforms of PKC with differing substrate specificities exist. To reassess the role of PKC in cytoskeletal reorganization, we compared the effects of diacylglycerol analogs and of PKC antagonists on kinase activity and on actin assembly in human neutrophils. Ruffling of the plasma membrane was assessed by scanning EM, and spatial redistribution of filamentous (F)-actin was assessed by scanning confocal microscopy. Staining with NBD-phallacidin and incorporation of actin into the Triton X-100-insoluble ("cytoskeletal") fraction were used to quantify the formation of (F)- actin. [32P]ATP was used to detect protein phosphorylation in electroporated cells. Exposure of neutrophils to 4 beta-PMA (an activator of PKC) induced protein phosphorylation, membrane ruffling, and assembly and reorganization of the actin cytoskeleton, whereas the 4a-isomer, which is inactive towards PKC, failed to produce any of these changes. Moreover, 1,2-dioctanoylglycerol, mezerein, and 3-(N- acetylamino)-5-(N-decyl-N-methylamino)-benzyl alcohol, which are nonphorbol activators of PKC, also promoted actin assembly. Although these effects were consistent with a role of PKC, the following observations suggested that stimulation of conventional isoforms of the kinase were not directly responsible for actin assembly: (a) Okadaic acid, an inhibitor of phosphatases 1 and 2A, potentiated PMA-induced protein phosphorylation, but not actin assembly; and (b) PMA-induced actin assembly and membrane ruffling were not prevented by the conventional PKC inhibitors 1-(5-isoquinolinesulfonyl)-2- methylpiperazine, staurosporine, calphostin C, or sphingosine at concentrations that precluded PMA-induced protein phosphorylation and superoxide production. On the other hand, PMA-induced actin assembly was inhibited by long-chain fatty acid coenzyme A esters, known inhibitors of nuclear PKC (nPKC). We conclude that PMA-induced actin assembly is unlikely to be mediated by the conventional isoforms of PKC, but may be mediated by novel isoforms of the kinase such as nPKC.

The long-term effects of aerosol pentamidine on pulmonary function. The Toronto Aerosolized Pentamidine Study (TAPS) Group

Aerosolized pentamidine (AP) has been widely used for prophylaxis of pneumocystis carinii pneumonia (PCP) since 1988. The objective of this study was to evaluate the long-term effects of AP on pulmonary function. Of 36 patients with AIDS who were receiving AP for secondary prophylaxis of PCP, 13 patients had been using AP continuously for more than 52 weeks. AP was given using a Fisoneb ultrasonic nebulizer with five loading doses of 60 mg over two weeks, followed by one dose of 60 mg every two weeks. Baseline PFT were TLC 92 +/- 14% pred, FVC 90 +/- 11% pred, FEV1 91 +/- 11% pred, FEF25-75 95 +/- 17% pred, and DLCO (corrected for hemoglobin) 70 +/- 22% pred. No significant change in TLC, FVC, FEV1, or DLCO was seen after 56 weeks of AP. There was a 20% fall in FEF25-75 seen after 56 weeks, which was statistically significant. However, the clinical significance of a fall of this magnitude in the FEF25-75 is uncertain. Similar results were seen in a smaller subset of patients who received AP for at least 76 weeks. Although the small sample size must be considered, this data suggests that there is no clinically significant change in pulmonary function associated with the use of AP for up to 76 weeks.

High incidence of bronchospasm with regular administration of aerosolized pentamidine

A systematic evaluation of changes in pulmonary status by objective spirometric assessment and subjective rating using visual analog scale was performed in a cohort of 134 patients receiving aerosolized pentamidine (AP) for the prevention of Pneumocystis carinii pneumonia. Significant bronchospasm defined as greater than or equal to 15 percent reduction in the forced expiratory volume in 1 s was noted in 26 of 100 (26 percent) of patients receiving AP alone. Despite the use of salbutamol (albuterol) as concurrent aerosolized treatment in 34 subjects, bronchospasm developed in 9 of 34 (26 percent) of the patients. The subjective respiratory status rating scale was found to be unreliable in correctly predicting the development of bronchospasm. We conclude that a high incidence of bronchospasm is present in patients receiving regular AP administration using an ultrasonic nebulizer as studied, and concurrent administration of salbutamol is not fully protective of this acute adverse pulmonary reaction.

An improved technique for management of dislocated posterior chamber implants

Many techniques for repositioning dislocated posterior chamber implants described in the recent literature involve intricate intraocular manipulation of a needle or other sharp instrument. The author describes an improved sulcus fixation technique, which combines the best features of external and internal approaches. Its main features involve temporary externalization of the haptics for easy and secured placement of suture knots, and subsequent reinternalization of the same haptics through horizontal sclerotomies directly external to the ciliary sulcus for precise fixation of the dislocated posterior chamber implant with consistency. Between May 1989 and December 1990, this technique was successfully used for posterior chamber intraocular lens repositioning in 12 cases. The main advantages of this technique include: (1) easy suture placement, (2) less chance of suture slippage with the secured knots, and (3) avoidance of difficult intraocular maneuvers and possible tissue injury. This improved technique expedites the process of posterior chamber implant repositioning.

A complexity reduction technique for image vector quantization

A technique for reducing the complexity of spatial-domain image vector quantization (VQ) is proposed. The conventional spatial domain distortion measure is replaced by a transform domain subspace distortion measure. Due to the energy compaction properties of image transforms, the dimensionality of the subspace distortion measure can be reduced drastically without significantly affecting the performance of the new quantizer. A modified LBG algorithm incorporating the new distortion measure is proposed. Unlike conventional transform domain VQ, the codevector dimension is not reduced and a better image quality is guaranteed. The performance and design considerations of a real-time image encoder using the techniques are investigated. Compared with spatial domain a speed up in both codebook design time and search time is obtained for mean residual VQ, and the size of fast RAM is reduced by a factor of four. Degradation of image quality is less than 0.4 dB in PSNR.

Bleomycin-induced Pulmonary Function Abnormalities

The usefulness of serial PFTs in identifying patients who are developing BIP was assessed in 59 men with non-seminomatous testicular carcinoma. The mean age was 27.7 years and all the patients received a standard three-course chemotherapy regimen consisting of vinblastine, bleomycin, and cis-diamminedichloroplatinum. The average dose of bleomycin was 555.5 units. Serial PFTs, chest roentgenograms, and medical assessments were done prior to each course of bleomycin. Nine (15.3 percent) patients developed pulmonary symptoms due to bleomycin and 23 (39 percent) had significant changes on chest x-ray films. The Dsb dropped significantly with bleomycin treatment; therefore, it is the most sensitive indicator of pulmonary response to bleomycin. However, the Dsb failed to differentiate patients with BIP from those without. The TLC was found to be a much more specific indicator of BIP because reduction in TLC correlated with the development of pulmonary symptoms and roentgenologic changes.

Mechanism of the initial charge separation in bacterial photosynthetic reaction centers

The initial electron transfer in reaction centers from Rhodobacter sphaeroides R26 was studied by a subpicosecond transient pump-probe technique. The measured kinetics at various wavelengths were analyzed and compared with several mechanisms for electron transfer. An unambiguous determination of the initial electron transfer mechanism in reaction centers cannot be made by studying the anion absorption region (640-690 nm), due to the spectral congestion in this region. However, correlations between the stimulated emission decay of the excited state of the special pair, P*, at 926 nm and bleaching of the bacteriopheophytin Qx absorption at 545 nm suggest that the electron transfer at 283 K is dominated by a two-step sequential mechanism, whereas one-step superexchange and the two-step sequential mechanism have about equal contributions at 22 K.

Pneumocystis carinii pneumonia associated with methotrexate therapy in rheumatoid arthritis

Opportunistic infections occur in patients with rheumatic diseases treated with low dose methotrexate (MTX) with or without other immunosuppressants. Our case report illustrates a fatal case of Pneumocystis carinii pneumonia in a patient with rheumatoid arthritis treated with low dose MTX and glucocorticoid. A review of the literature reveals other opportunistic infections such as Cryptococcus, Nocardia, and herpes zoster presenting in such patients. These occurrences suggest that MTX should be used cautiously in patients with rheumatic disease receiving concomitant medical therapy.

Sleep apnea and systemic hypertension: a causal association review

OBJECTIVE

To critically examine the causal association between sleep apnea syndrome and hypertension.

METHODS

A retrospective systematic critique of five epidemiologic studies published in the English literature during 1978 to 1989 identified on Medline and manual literature searches. The evidence was evaluated using the standard observational criteria for causation: strength of association, consistency, dose-response relationship, temporal sequence, specificity, and biologic plausibility.

RESULTS

We found evidence to support a causal association between sleep apnea syndrome and hypertension in consistency and specificity and some evidence to suggest a dose-response relationship. Review of the data dealing with the mechanisms important in the pathogenesis of sleep apnea and hypertension allowed us to advance several theories to provide support for biologic plausibility.

CONCLUSION

We concluded that there is a positive association--relative risk estimate between 1.3 and 40--for sleep apnea syndrome and hypertension, but the risk association is unstable. Thus, we believe that there is insufficient data to justify doing polysomnography as part of the routine diagnostic work-up for patients with hypertension.