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Background Limited data are available on the association between clinically measured disease severity markers and quality of life (QOL) in idiopathic pulmonary fibrosis (IPF). The study examined the associations between objective disease severity metrics and QOL in a contemporary IPF population. Methods This study evaluated baseline data from patients enrolled in the multicenter, US-based Idiopathic Pulmonary Fibrosis Prospective Outcomes Registry between June 2014 and July 2018. Disease severity metrics included FVC % predicted, diffusing capacity for carbon monoxide (Dlco) % predicted, supplemental oxygen use with activity, supplemental oxygen use at rest, and two summary scores (the Gender-Age-Lung Physiology index, based on gender, age, and % predicted values for Dlco and FVC; and the Composite Physiologic Index, based on % predicted values for Dlco, FVC, and FEV1). Multivariable adjusted regression models were used to examine cross-sectional associations between each severity measure and St. George's Respiratory Questionnaire (SGRQ) total score. Results Among 829 patients with complete SGRQ data, the median (interquartile range) SGRQ score at enrollment was 40 (26-53), with higher scores indicating worse QOL. Modest SGRQ impairments were observed with increasing Gender-Age-Lung Physiology score (2.9 [1.8-4.0] per 1-point increase] and with increasing Composite Physiologic Index scores (3.0 [2.4-3.6] per 5-point increase). Substantial SGRQ impairments were observed for oxygen use with activity (15.6 [12.9-18.2]), oxygen use at rest (16.2 [13.0-19.4]), and decreasing Dlco (5.0 [4.0-6.1] per 10% decrease in % predicted). Conclusions Objective measures of disease severity, including severity scores, physiologic parameters, and supplemental oxygen use, are associated with worse QOL in patients with IPF. Trial Registry ClinicalTrials.gov; No.: NCT01915511; URL: www.clinicaltrials.gov.

The formation of complexes between Rab11 and its effectors regulates multiple aspects of membrane trafficking, including recycling and ciliogenesis. WD repeat-containing protein 44 (WDR44) is a structurally uncharacterized Rab11 effector that regulates ciliogenesis by competing with prociliogenesis factors for Rab11 binding. Here, we present a detailed biochemical and biophysical characterization of the WDR44-Rab11 complex and define specific residues mediating binding. Using AlphaFold2 modeling and hydrogen/deuterium exchange mass spectrometry, we generated a molecular model of the Rab11-WDR44 complex. The Rab11-binding domain of WDR44 interacts with switch I, switch II, and the interswitch region of Rab11. Extensive mutagenesis of evolutionarily conserved residues in WDR44 at the interface identified numerous complex-disrupting mutations. Using hydrogen/deuterium exchange mass spectrometry, we found that the dynamics of the WDR44-Rab11 interface are distinct from the Rab11 effector FIP3, with WDR44 forming a more extensive interface with the switch II helix of Rab11 compared with FIP3. The WDR44 interaction was specific to Rab11 over evolutionarily similar Rabs, with mutations defining the molecular basis of Rab11 specificity. Finally, WDR44 can be phosphorylated by Sgk3, with this leading to reorganization of the Rab11-binding surface on WDR44. Overall, our results provide molecular detail on how WDR44 interacts with Rab11 and how Rab11 can form distinct effector complexes that regulate membrane trafficking events.

Diacylglycerol (DAG) activates the eight conventional and novel isozymes of protein kinase C (PKC) by binding to their C1 domains. The crystal structure of PKCβII in a partially activated conformation showed how the C1B domain regulates activity by clamping a helix in the C-terminal AGC extension of the kinase domain. Here we show that the global three-dimensional shape of the conventional and novel PKCs is conserved despite differences in the order of the domains in their primary sequences. The membrane translocation phenotypes of mutants in the C1B clamp are consistent across all DAG-activated PKCs, demonstrating conservation of this regulatory interface. We now identify a novel interface that sequesters the C1A domain in PKCβII in a membrane-inaccessible state and we generalize this to all DAG-activated PKCs. In the conventional PKCs, we identify a novel element of their C2 domains that additionally contributes to the stability of the inactive conformation. We demonstrate that the interdomain linkers play important roles in permitting and stabilizing this state. We propose a multi-step activation mechanism in which the sequential and cooperative binding of the regulatory domains to the membrane is coupled to allosteric activation of the kinase domain by DAG and that acquisition of full catalytic activity requires DAG binding to the C1B domain. In light of the conservation of shape and intramolecular architecture, we propose that this mechanism is common to all DAG-activated PKCs.

The term “social Darwinism” owes its currency and many of its connotations to Richard Hofstadter’s influential Social Darwinism in American Thought, 1860–1915 (SDAT). The postSDAT meanings of “social Darwinism” are the product of an unresolved Whiggish tension in SDAT: Hofstadter championed economic reform over free markets, but he also condemned biology in social science, this while many progressive social scientists surveyed in SDAT offered biological justifications for economic reform. As a consequence, there are, in effect, two Hofstadters in SDAT. The first (call him Hofstadter1) disparaged as “social Darwinism” biological justification of laissez-faire, for this was, in his view, doubly wrong. The second Hofstadter (call him Hofstadter2) documented, however incompletely, the underside of progressive reform: racism, eugenics and imperialism, and even devised a term for it, “Darwinian collectivism.” This essay documents and explains Hofstadter’s ambivalence in SDAT, especially where, as with Progressive Era eugenics, the “two Hofstadters” were at odds with each other. It explores the historiographic and semantic consequences of Hofstadter’s ambivalence, including its connection with the Left’s longstanding mistrust of Darwinism as apology for Malthusian political economy.

An abnormal growth form called mound has been hypothesized to be a neoplasm in the filamentous fungus Schizophyllum commune. An alternative hypothesis is that mounds represent some unusual developmental form in the fruiting body morphogenetic pathway. Hydrophobin proteins have been found in fruiting bodies where they line the surface of gas exchange pores and function to keep the pores hydrophobic. To further determine possible relationships between mounds and fruiting bodies, mound tissue was examined for gas exchange pores and the presence of hydrophobins. Cryoscanning electron microscopic images revealed the presence of channels in mound tissue and presumptive hydrophobin rodlets similar to the air channels in fruiting bodies. Hydrophobin gene expression was also measured in mound tissue using quantitative real-time PCR and showed both monokaryotic and dikaryotic mound tissue exhibited high expression of the dikaryotic specific Sc4 hydrophobin gene. In contrast, Sc4 hydrophobin expression was barely detectable in monokaryotic fruiting bodies. The expression of Sc4 hydrophobin genes in mounds suggests mound development uses this aspect of the dikaryotic fruiting developmental pathway.

Summary Protein kinase C (PKC) isozymes are the paradigmatic effectors of lipid signaling. PKCs translocate to cell membranes and are allosterically activated upon binding of the lipid diacylglycerol to their C1A and C1B domains. The crystal structure of full-length protein kinase C βII was determined at 4.0 A, revealing the conformation of an unexpected intermediate in the activation pathway. Here, the kinase active site is accessible to substrate, yet the conformation of the active site corresponds to a low-activity state because the ATP-binding side chain of Phe629 of the conserved NFD motif is displaced. The C1B domain clamps the NFD helix in a low-activity conformation, which is reversed upon membrane binding. A low-resolution solution structure of the closed conformation of PKCβII was derived from small-angle X-ray scattering. Together, these results show how PKCβII is allosterically regulated in two steps, with the second step defining a novel protein kinase regulatory mechanism.

Purpose This study analyzed the accuracy of the Inoveon Diabetic Retinopathy (DR-3DT) system (Inoveon Corp., Oklahoma City, OK), a scalable evaluation method for the management of diabetic retinopathy using high-quality digital retinal imaging. Design An independent, masked, cross-sectional, clinical validation study. Participants Two hundred ninety adult patients with diabetes from the Chickasaw Nation's Carl Albert Indian Health Facility in Ada, Oklahoma. Methods All participants underwent DRS7 imaging using a Zeiss FF450 fundus camera with images recorded on 35-mm film and a Kodak DCS520 digital camera back. Masked double grading with independent third reader adjudication yielded an Early Treatment Diabetic Retinopathy Study (ETDRS) Final Retinopathy Severity Scale Level (ETDRS Level) and macular edema stage for each eye. The presence of ≥ ETDRS Level 53, questionable or definite clinically significant macular edema in either eye, or ungradeable images was defined as a threshold event requiring referral. Main outcome measures Accuracy (sensitivity, specificity, predictive values) of the digital system relative to the film "gold standard" on the threshold referral criteria per patient. Results All patients with gradeable 35-mm slides from at least one eye were included in this per patient analysis (n = 290). The prevalence of threshold events was 19.3%. The sensitivity of the digital system in detecting threshold events was 98.2% (95% confidence interval [CI], 90.5%–100.0%) and specificity 89.7% (95% CI, 85.1%–93.3%). The positive predictive value was 69.5% and negative predictive value 99.5% for this sample. Conclusions When compared with the "gold standard," Inoveon's DR-3DT system provides highly accurate diabetic retinopathy referral decisions. Given their inherent advantages, high-quality digital imaging systems could replace the film "gold standard" as the basis for scalable, accessible, diabetic retinopathy evaluation.

Protein kinase B/Akt regulates cellular metabolism, survival, and proliferation in response to hormones and growth factors. Hyperactivation of Akt is frequently observed in cancer, while Akt inactivation is associated with severe diabetes. Here, we investigated the molecular and cellular mechanisms that maintain Akt activity proportional to the activating stimulus. We show that binding of phosphatidylinositol-3,4,5-trisphosphate (PIP3) or PI(3,4)P2 to the PH domain allosterically activates Akt by promoting high-affinity substrate binding. Conversely, dissociation from PIP3 was rate limiting for Akt dephosphorylation, dependent on the presence of the PH domain. In cells, active Akt associated primarily with cellular membranes. In contrast, a transforming mutation that uncouples kinase activation from PIP3 resulted in the accumulation of hyperphosphorylated, active Akt in the cytosol. Our results suggest that intramolecular allosteric and cellular mechanisms cooperate to restrict Akt activity to cellular membranes, thereby enhancing the fidelity of Akt signaling and the specificity of downstream substrate phosphorylation.

Purpose To describe the results from a statewide preschool vision screening program using the MTI PhotoScreener (Medical Technology and Innovations, Inc., Cedar Falls, IA). Design Cross-sectional study. Participants A total of 15,059 children aged 6 to 47 months enrolled in childcare and preschool settings throughout the state of Tennessee. Methods Volunteers from local Lions Clubs took photoscreening photographs of children in a statewide effort. Photographs were interpreted at the Vanderbilt Ophthalmic Photography Reading Center using predetermined criteria. Children who failed the screening were referred to community ophthalmologists or optometrists who performed a comprehensive evaluation and forwarded the results to the authors. Main outcome measures Referral rate, unreadable rate, and predictive value positive (PVP). Results During the 2 years of the screening program, 15,059 children were screened in 850 screenings. The screening referred 1013 children (6.7%), and 704 photographs (4.7%) were unreadable. Children who failed the screening had a significant abnormality (strabismus, anisometropia, high hypermetropia, high astigmatism, or high myopia) in 320 of the 531 cases where adequate follow-up results were reported. The PVP ranged from 84% when a diagnosis of strabismus was suggested by the photoscreen reading to 41% for astigmatism. Despite intense attention to follow-up, many children who failed the screening never received a formal eye examination. Conclusions The MTI PhotoScreener can be used by volunteers to screen preschool children and can have a high PVP in organized settings, provided that meticulous attention is paid to photograph interpretation and quality control. The PVP of the MTI PhotoScreener depends on the diagnosis suggested when the photograph is read. Significant obstacles exist in obtaining care for those who fail screening.

Biliary obstruction, produced by common bile duct ligation or alpha-naphthylisothiocyanate (ANIT) treatment in rats, has been associated with the development of type I biliary epithelial cell (BEC) hyperplasia. However, the exact mechanism(s) by which bile duct obstruction lead(s) to this proliferative lesion are not clear. The present studies were designed to determine if cholestasis, in the absence of biliary obstruction, would result in type I BEC hyperplasia. Male Sprague-Dawley rats were given a single oral dose of 150 mg/kg ANIT or i.v. doses of estradiol glucuronide (E2-17G; 21 mumol/kg/h for 48 h) to produce obstructive and non-obstructive cholestasis, respectively. E2-17G treatment resulted in cholestasis that was comparable in extent and duration to that observed following ANIT treatment. E2-17G and ANIT treatments produced comparable increases in serum bile acids (55- to 60-fold) and activities of ALT (36- to 38-fold), ALP (4- to 5-fold), and 5'-nucleotidase (7- to 11-fold), respectively, compared to controls. Both ANIT and E2-17G also increased serum bilirubin concentrations. ANIT treatment resulted in significant increases in biliary glucose concentrations that were associated with BEC damage/necrosis and obstruction of the bile duct lumen. Conversely, no evidence of BEC damage was observed in E2-17G-treated rats. Nonetheless, BEC hyperplasia was observed in the majority of rats following treatment with either ANIT or E2-17G, assessed by light microscopy and by BrdU immunohistochemistry. These data indicate that E2-17G treatment produces nonobstructive cholestasis and type I BEC hyperplasia, suggesting that biliary obstruction is not a prerequisite for type I BEC hyperplasia in rats. Differences in the time of onset of hyperplasia were observed: hyperplasia was noted immediately following 48 h of E2-17G-induced cholestasis but occurred several days after ANIT-induced cholestasis had subsided. Since the magnitude/duration of cholestasis was similar in the two models but the temporal association between cholestasis and type I BEC hyperplasia were different, these data suggest that the proliferative stimulus may be different in the two models and that E2-17G-induced type I BEC hyperplasia may not be attributed solely to cholestasis.

Summary Background There is substantial circumstantial evidence that CD4 lymphocytes have a role in the pathogenesis of chronic asthma. We investigated the efficacy and safety in severe corticosteroid-dependent asthma of a single intravenous infusion of keliximab (IDEC CE9·1), a chimeric monoclonal antibody to CD4. Methods 22 patients were recruited from two asthma clinics. In an ascending-dose design, the first eight patients were assigned 0·5 mg/kg keliximab (six) or placebo (two); the next seven were assigned 1·5 mg/kg (five) or placebo (two); and the last seven were assigned 3·0 mg/kg (five) or placebo (two). Masked data on safety for each dose group were assessed before progression to the next dose. Patients kept a daily symptom diary and measured morning and evening peak expiratory flow (PEF) at home. PEF and forced expiratory volume in 1 s (FEV 1 ) were measured at follow-up clinic visits. Findings Patients given 0·5 mg/kg or 1·5 mg/kg keliximab and placebo recipients did not differ in change from baseline of PEF, FEV 1 , or symptom score. Those given 3·0 mg/kg keliximab differed significantly from placebo recipients in change in morning PEF (median area under curve [AUC] 445 vs −82·5, p=0·005) and evening PEF (median AUC 548 vs −85, p=0·014). Symptom score showed the same pattern (though differences did not achieve significance), but there was no difference in clinic FEV 1 . There were no serious adverse effects related to treatment. Two patients had mild exacerbations of eczema and one developed a transient maculopapular rash. All doses of keliximab were associated with a reduction from baseline in CD4 count. Interpretation Our findings raise the possibility that T-cell-directed treatment may be an alternative approach to the treatment of severe asthma.

These studies were designed to evaluate the importance of bile duct obstruction in the pathogenesis of alpha-naphthylisothiocyanate (ANIT)-induced biliary epithelial cell (BEC) hyperplasia in rats. Hepatobiliary function and morphology were evaluated in adult male Sprague-Dawley rats 16, 24, 48, 72, 120, and 168 hr after a single oral dose of ANIT (0, 25, 75, or 150 mg/kg). After 75 or 150 mg/kg ANIT, multifocal bile duct obstruction was observed at 48 and 72 hr and preceded BEC hyperplasia which occurred at 120 and 168 hr. BEC proliferation, reflected by 5-bromo-2'-deoxyuridine (BrdU) incorporation, occurred at doses and at time points coinciding with BEC necrosis and/or bile duct obstruction. In contrast, 25 mg/kg ANIT produced minimal BEC damage and no evidence of bile duct obstruction or BEC hyperplasia. In a separate experiment, BEC proliferation was evaluated following bile duct ligation or ANIT treatment (150 mg/kg). The onset and peak of BEC proliferation occurred 24 and 48 hr, respectively, following bile duct obstruction resulting from either ligation or ANIT treatment. Furthermore, BEC proliferation occurred at all levels of the biliary tree in both bile duct-ligated and ANIT-treated rats. These data indicate that (a) dose-response curves for ANIT-induced bile duct obstruction and BEC hyperplasia are similar; (b) ANIT-induced BEC proliferation and bile duct obstruction precedes BEC hyperplasia; (c) BEC proliferation occurred at doses/timepoints associated with BEC damage and bile duct obstruction; and (d) once ANIT-induced bile duct obstruction occurs, the spatial and temporal aspects of BEC proliferation are comparable to those following biliary obstruction induced by bile duct ligation. Collectively, these data suggest that ANIT-induced BEC hyperplasia is secondary to intrahepatic bile duct obstruction.

Historians often make Christian belief and evolutionary science adversaries (as perhaps best exemplified by accounts of the 1925 Scopes trial), but Progressive Era American political economy allied Christian belief and evolutionary science. Leading progressive economists, notably the evangelicals attached to the Social Gospel movement, readily assimilated Darwinism to their religiously motivated project of economic reform. This essay argues that the progressive economists' merger of evolutionary science and Christian belief was made possible by the fact that the Social Gospel was itself already (in part) an accommodation to the implications of Darwinism, and that Progressive Era evolutionary science was protean, fragmented and plural, enabling intellectuals to enlist evolutionary science in support of diverse, even opposed positions in political economy.

Various stages of the morel life-cycle are studied cytologically. Photomicrographic evidence demonstrates that the average number of nuclei per cellular compartment in vegetative hyphae of Morchella is 10–15 and that hyphal fusions are quite frequent. The resting structures, the sclerotia, are actually pseudosclerotia which form from the repeated branching and enlargement of terminal hyphae from either primary (homokaryotic) or secondary (heterokaryotic) hyphae. Photomicrographs also depict the development of fruiting body primordia. Photomicrographs of ascus development demonstrate autogamy rather than de novo heterokaryon formation by hyphal fusion in the subhymenial layer of the fruiting body. For the first time a comprehensive life-cycle diagram of the morel is introduced.

The original progressives were not that progressive: they proposed eugenic remedies for the immigrants, women, blacks and mental defectives they blamed for low wages, promoted an illiberal vision of women's economics interests, endorsed survival of the fittest doctrine (so long as the state chose the fittest), advocated imperial adventures, and embraced the scientifically managed corporation. A more complete portrait of the progressives recognizes this illiberal strain in progressive economic reform and its origins in anti-individualism, statism, social efficiency, and planning by scientific experts. The progressive vision of economic reform - what I call expertocracy - is contrasted with John Bates Clark's neoclassical alternative, market failure remedy.

Appropriate tyrosine kinase signaling depends on coordinated sequential coupling of protein-protein interactions with catalytic activation. Focal adhesion kinase (FAK) integrates signals from integrin and growth factor receptors to regulate cellular responses including cell adhesion, migration, and survival. Here, we describe crystal structures representing both autoinhibited and active states of FAK. The inactive structure reveals a mechanism of inhibition in which the N-terminal FERM domain directly binds the kinase domain, blocking access to the catalytic cleft and protecting the FAK activation loop from Src phosphorylation. Additionally, the FERM domain sequesters the Tyr397 autophosphorylation and Src recruitment site, which lies in the linker connecting the FERM and kinase domains. The active phosphorylated FAK kinase adopts a conformation that is immune to FERM inhibition. Our biochemical and structural analysis shows how the architecture of autoinhibited FAK orchestrates an activation sequence of FERM domain displacement, linker autophosphorylation, Src recruitment, and full catalytic activation.

The biochemical basis for the marked difference in the rate of the hepatic metabolism of 2,2',4,4',5,5'-hexachlorobiphenyl (245-HCB) by Beagle dogs and Sprague-Dawley rats has been investigated. Control dog liver microsomes metabolize this substrate 15 times faster than control rat liver microsomes. Upon treatment with phenobarbital (PB), at least two cytochrome P-450 isozymes are induced in the dog, and the hepatic microsomal metabolism of 245-HCB is increased on both a per nanomole P-450 basis (twofold) and a per milligram protein basis (fivefold). One of the PB-induced isozymes, PBD-2, has been purified to a specific content of 17-19 nmol/mg protein and to less than 95% homogeneity, as evidenced by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. In a reconstituted system containing cytochrome b5, this isozyme shows an activity toward 245-HCB which is greater than threefold that seen in intact liver microsomes from PB-induced dogs. A reconstituted system containing the major isozyme induced by PB in the rat (PB-B) metabolizes 245-HCB at 1/10 the rate observed with purified PBD-2. Antibody inhibition studies have shown that PBD-2 accounts for greater than 90% of the hepatic microsomal metabolism of 245-HCB in control and PB-induced dogs, while PB-B only accounts for about half of the metabolism of this compound by microsomes obtained from PB-treated rats. Immunoblot analysis has revealed that the level of PBD-2 in dog liver microsomes increases nearly sixfold with PB treatment, and this increase correlates well with the fivefold increase in the rate of hepatic microsomal metabolism of 245-HCB by dogs. Together these data support a primary role for isozyme PBD-2 in the hepatic metabolism of 245-HCB in control and PB-induced dogs. In addition, these results suggest that, in contrast to rats, dogs can readily metabolize 245-HCB as a result of the presence of a cytochrome P-450 isozyme with efficient 245-HCB metabolizing activity.

Synthesis of hepatic ribosomal precursor RNA (45S rRNA) was investigated in rats treated with single intraperitoneal injections of methylcholanthrene (MC) (30 mg/kg) or phenobarbital (PB) (100 mg/kg). Labelling in vivo of total nuclear RNA and of nuclear 45S rRNA with [ 3 H]orotic acid was unchanged in rats sacrificed 3 or 20 hr after reveiving a single dose of MC. These results agreed with measurements in vitro of nucleolar RNA polymerase activity, which was unaffected by either MC or PB pretreatment. In rats sacrificed 6 hr after receiving an injection of PB or 3 or 20 hr after receiving an injection of MC, incorporation of [ 3 H]UTP into isolated nucleoli was not enhanced. Labeling in vivo of microsomal 28S and 18S rRNA with [ 3 H]orotic acid increased 50 per cent 6 hr after a single dose of PB but was unchanged 3 or 20 hr after a single dose of MC. The stability of 45S rRNA in rats treated with PB or MC was tested in a nuclear incubation system. After incubation of nuclei at 37° for 2 min in 0.25 M sucrose containing 5 mM MgCl 2 , RNA was extracted and layered on 10–40% sucrose gradients. Planimetric analysis of these sucrose gradients demonstrated that, 16 hr after PB treatment, the stability of 45S rRNA was increased over that of controls, whereas 20 hr after MC, 45S rRNA stability was unchanged. These results suggest that PB, but not MC, enhances post-transcriptional stability of 45S rRNA and labeling in vivo of microsomal RNA. Neither MC nor PB increases synthesis of ribosomal precursor RNA.

Somatic recombination was compared in genetically identical diploid and dikaryotic mycelia heteroallelic for the recessive morphological marker,mnd, and six other genetic markers. Although recombination including the chromosomal segment containingmnd was detected in both types of somatic cells, the underlying process appears to be different. The diploids showed parasexual recombination associated with sectoring, whereas the dikaryon typically showed, with rare exception, a peculiar type of internuclear transfer resulting in a single genetic alteration in themnd chromosomal region. Some of the haploidmnd end products recovered from diploids produced unusual and unstable dikaryotic transformed mound tissue when mated tomnd+ strains. The instability produced normal dikaryotic sectors which proved upon analysis to be revertants to nonmounds. The results suggest that these “transformed” dikaryotic mound cells contained a donormnd nucleus and a recipient nucleus which is somehow heteroallelic [mndmnd+]. Reversion from a mound to a nonmound cell is envisioned as loss of the previously acquiredmnd allele. These results suggest that unstable mounds formed in dikaryotic colonies do not occur by a somatic recombination mechanism involving allelic substitution, as previously hypothesized, but rather by the addition of genetic material to themnd+ nucleus without genetic loss. Whatever the precise mechanism for stable and unstable mound development in dikaryons, the studies detailed within suggest that a diploid nucleus is an unlikely intermediate in the somatic recombination process.

The accumulation of slime by diallele crosses involving fruiting and non-fruiting monokaryons has been measured. Its accumulation does not appear to be correlated with the production of monokaryotic fruit bodies.

Leukotriene B4 was metabolized in rat hepatic microsomes to two products. Mass spectral analysis of these two metabolites indicated that the major metabolite was the 20-hydroxy metabolite while the minor metabolite was the 19-hydroxy metabolite. The formation of these metabolites required NADPH and was linear with time (20 min) and protein (1.6 mg/ml). The Km apparent and Vmax for omega hydroxylation of LTB4 was 14 uM and 0.138 nmol/min/mg protein. In contrast, the km and Vmax for omega minus one hydroxylation was 54 uM and 0.093 nmol/min/mg protein. These results suggest that omega and omega minus one hydroxylations of LTB4 may be mediated by different isozymes of hepatic P-450.

Several spontaneous variants of Schizophyllum commune , recovered both from unstable diploids and from meiotic progeny, have been found to prevent the conventional pattern of internuclear transfer of the recessive morphological marker mnd . These variants, designated mnd mob , still express the mound phenotype of unregulated hyperplasia in monokaryons and a modified mound phenotype in dikaryons homoallelic for mnd . The high incidence of mnd mob variants (ca. 2.5%) occurring among meiotic progeny of the cross mnd mob + × mnd + mob + , together with the failure to obtain mnd + mob recombinants from crosses between mnd mob and mnd + mob + , suggests some origin other than point mutation as the basis for generating mnd mob variants. It is proposed that mob + is a transposable element closely linked to or within mnd and that this element might be responsible for the internuclear transfer of the mnd locus suggested to occur in the somatic mnd recombinations reported previously in [ mnd + mnd + ] dikaryons.

Panretinal photocoagulation (PRP) can produce damage to all layers of the retina, including the nerve fiber layer. The hypothesis that these changes in the nerve fiber layer may alter the contour of the optic disc and change the cup-to-disc (C/D) ratio was tested. In a masked retrospective study, the authors evaluated the stereoscopic disc photographs of 100 patients with proliferative diabetic retinopathy (PDR) before and 1 year after undergoing PRP. The fellow untreated eyes were used as controls. Neither argon nor xenon PRP produced a significant change in the C/D ratio. Ophthalmology 96:211-216,1989

Acetaminophen killed cultured hepatocytes prepared from male rats induced with 3-methylcholanthrene by two distinct mechanisms. With 0.5 to 5 m m acetaminophen, cell killing within 4 h depended on the inhibition of glutathione reductase by 1,3-bis(chloro-ethyl)-1-nitrosourea (BCNU) and was accompanied by the peroxidation of cellular lipids as assessed by the accumulation of malondialdehyde. The antioxidant diphenylphenyl-enediamine (DPPD) prevented both the peroxidation of lipids and the death of the cells. By contrast, DPPD had no effect on the metabolism of acetaminophen as assessed by the extent of the covalent binding of [ 3 H]acetaminophen; by the rate and extent of the depletion of glutathione; and by the accumulation of acetaminophen metabolites in the culture medium. It is concluded that the peroxidation of the phospholipids of cellular membranes is the mechanism whereby 0.5 to 5 m m acetaminophen lethally injures cultured hepatocytes. With 10–20 m m acetaminophen, cell killing at 4 h still depended on BCNU. However, the amount of malondialdehyde in the cultures progressively decreased in parallel with the decreasing ability of DPPD to protect the cells. With 20 m m acetaminophen, there was no evidence of lipid peroxidation, and DPPD had no protective effect. Thus, a second mechanism of lethal cell injury with 10–20 m m acetaminophen is independent of lipid peroxidation and insensitive to antioxidants.