Spiraling Risk: Visualizing the multilevel factors that socially pattern HIV risk among gay, bisexual & other men who have sex with men using Complex Systems Theory.

PURPOSE OF REVIEW: Global disparities in HIV infection, particularly among gay, bisexual, and other men who have sex with men (GBMSM), indicate the importance of exploring the multi-level processes that shape HIV's spread. We used Complex Systems Theory and the PRISMA guidelines to conduct a systematic review of 63 global reviews to understand how HIV is socially patterned among GBMSM. The purpose was to conduct a thematic analysis of the reviews to (1) synthesize the multi-level risk factors of HIV risk, (2) categorize risk across the socioecological model, and (3) develop a conceptual model that visualizes the interrelated factors that shape GBMSMS's HIV "risk." RECENT FINDINGS: We included 49 studies of high and moderate quality studies. Results indicated that GBMSM's HIV risk stems from the individual, interpersonal, and structural levels of the socioecological model. We identified a few themes that shape GBMSM's risk of HIV infection related to biomedical prevention methods; sexual and sex-seeking behaviors; behavioral prevention methods; individual-level characteristics and syndemic infections; lived experiences and interpersonal relationships; country-level income; country-level HIV prevalence; and structural stigma. The multi-level factors, in tandem, serve to perpetuate GBMSM's risk of HIV infection globally. The amalgamation of our thematic analyses from our systematic reviews of reviews suggests that the risk of HIV infection operates in an emergent, dynamic, and complex nature across multiple levels of the socioecological model. Applying complex systems theory indicates how multilevel factors create a dynamic and reinforcing system of HIV risk among GBMSM.

High precision optical cavity length and width measurements using double modulation.

We use doubly phase modulated light to measure both the length and the linewidth of an optical resonator with high precision. The first modulation is at RF frequencies and is set near a multiple of the free spectral range, whereas the second modulation is at audio frequencies to eliminate offset errors at DC. The light in transmission or in reflection of the optical resonator is demodulated while sweeping the RF frequency over the optical resonance. We derive expressions for the demodulated power in transmission, and show that the zero crossings of the demodulated signal in transmission serve as a precise measure of the cavity linewidth at half maximum intensity. We demonstrate the technique on two resonant cavities, with lengths 16 m and a 4 km, and achieve an absolute length accuracy as low as 70 ppb. The cavity width for the 16 m cavity was determined with an accuracy of approximately 6000 ppm. Through an analysis of the systematic errors we show that this result could be substantially improved with the reduction of technical sources of uncertainty.

The management of diabetes in terminal illness related to cancer.

The management of diabetes during terminal illness is complex, with lack of agreement and consensus among physicians and multidisciplinary teams. Despite the plethora of guidelines available for the management of diabetes, there exists no agreed, evidence-based strategy for managing diabetes during terminal illness and at the end of life. A number of physiological factors may influence glycaemic control during terminal illness. These include anorexia, cachexia, malabsorption, renal and hepatic failure. Furthermore, controversy exists on the frequency of blood glucose monitoring, the optimum blood glucose range and how to achieve this. We review the factors influencing blood glucose during terminal illness and provide a suggested approach to managing patients with type 1 and type 2 diabetes during the early and late stages of terminal illness.

The dynamin-related GTPase Dnm1 regulates mitochondrial fission in yeast.

The dynamin-related GTPase Dnm1 controls mitochondrial morphology in yeast. Here we show that dnm1 mutations convert the mitochondrial compartment into a planar 'net' of interconnected tubules. We propose that this net morphology results from a defect in mitochondrial fission. Immunogold labelling localizes Dnm1 to the cytoplasmic face of constricted mitochondrial tubules that appear to be dividing and to the ends of mitochondrial tubules that appear to have recently completed division. The activity of Dnm1 is epistatic to that of Fzo1, a GTPase in the outer mitochondrial membrane that regulates mitochondrial fusion. dnm1 mutations prevent mitochondrial fragmentation in fzo1 mutant strains. These findings indicate that Dnm1 regulates mitochondrial fission, assembling on the cytoplasmic face of mitochondrial tubules at sites at which division will occur.

The yeast gene, MDM20, is necessary for mitochondrial inheritance and organization of the actin cytoskeleton.

In Saccharomyces cerevisiae, the growing bud inherits a portion of the mitochondrial network from the mother cell soon after it emerges. Although this polarized transport of mitochondria is thought to require functions of the cytoskeleton, there are conflicting reports concerning the nature of the cytoskeletal element involved. Here we report the isolation of a yeast mutant, mdm20, in which both mitochondrial inheritance and actin cables (bundles of actin filaments) are disrupted. The MDM20 gene encodes a 93-kD polypeptide with no homology to other characterized proteins. Extra copies of TPM1, a gene encoding the actin filament-binding protein tropomyosin, suppress mitochondrial inheritance defects and partially restore actin cables in mdm20 delta cells. Synthetic lethality is also observed between mdm20 and tpm1 mutant strains. Overexpression of a second yeast tropomyosin, Tpm2p, rescues mutant phenotypes in the mdm20 strain to a lesser extent. Together, these results provide compelling evidence that mitochondrial inheritance in yeast is an actin-mediated process. MDM20 and TPM1 also exhibit the same pattern of genetic interactions; mutations in MDM20 are synthetically lethal with mutations in BEM2 and MYO2 but not SAC6. Although MDM20 and TPM1 are both required for the formation and/or stabilization of actin cables, mutations in these genes disrupt mitochondrial inheritance and nuclear segregation to different extents. Thus, Mdm20p and Tpm1p may act in vivo to establish molecular and functional heterogeneity of the actin cytoskeleton.

Effect of aromatase inhibitors on estrogen 2-hydroxylase in rat liver.

The effect of aromatase inhibitors, 4-hydroxyandrostenedione, CGS 16949A and aminoglutethimide on the inhibition of estrogen 2-hydroxylase activity in rat liver microsomes in vitro and on its induction in vivo has been examined. Estrogen 2-hydroxylase was found to have over twice the affinity for estradiol compared to estrone. Using high pressure liquid chromatography and employing estradiol as a substrate, the IC50 values were 2.2, 98, 110 and 908 microM for the reference compound ketoconazole and the aromatase inhibitors, 4-hydroxyandrostenedione, CGS 16949A and aminoglutethimide, respectively. Similar IC50 values were obtained using estrone as a substrate and by a tritiated water method employing estradiol as a substrate. The Km value for estrogen 2-hydroxylase with estradiol as a substrate using a tritiated water method was 4.3 microM with a Vmax of 11.89 nmol/h/mg. Ketoconazole, CGS 16949A and aminoglutethimide exhibited non-competitive inhibition whereas 4-hydroxyandrostenedione appeared to be a competitive inhibitor of estrogen 2-hydroxylase. The Ki values were 2.6, 72, 114 and 958 microM for ketoconazole, 4-hydroxyandrostenedione, CGS 16949A and aminoglutethimide, respectively. All three aromatase inhibitors were weak inhibitors of estrogen 2-hydroxylase as compared to the reference drug, ketoconazole. Following treatment of rats with aminoglutethimide (40 mg/kg/day; i.p.; for 3 days), estrogen 2-hydroxylase activity was increased by 28 and 30% using estradiol and estrone as substrates, respectively. Following treatment of rats with CGS 16949A (2 mg/kg/day; p.o.; for 3 days), the corresponding increase in estrogen 2-hydroxylase activity was 48 and 44%. The results of this study indicate that the aromatase inhibitors, aminoglutethimide and CGS 16949A are only weak inhibitors of estrogen 2-hydroxylase activity in vitro and show no evidence of inhibition in vivo. On the contrary, there was some evidence to suggest that both aminoglutethimide and CGS 16949A induce estrogen metabolism following repeated administration. Therefore, aminoglutethimide and CGS 16949A may lower estrogen levels not only by primarily inhibiting their synthesis but also by inducing the metabolism of estrogens.

Biosynthesis and incorporation into protein of norleucine by Escherichia coli.

The methionine analog norleucine was produced during the synthesis of bovine somatotropin by Escherichia coli strain W3110G containing the recombinant plasmid pBGH1. Norleucine was generated by the leucine biosynthetic pathway from pyruvate or alpha-ketobutyrate in place of alpha-ketoisovalerate as the initial substrate. The intracellular level of norleucine was high enough to permit the analog to compete successfully with methionine for incorporation into protein. Two ways were found to prevent either the formation of norleucine or its incorporation into protein. The endogenous synthesis of norleucine was eliminated by deleting the leucine operon. The addition of sufficient methionine or 2-hydroxy-4-methylthiobutanoic acid, a precursor of methionine, to the culture medium prevented any norleucine from being incorporated into protein.

Age-related changes of the retinal pigment epithelium of cats with Chediak-Higashi syndrome.

The eyes of 7, 9, and 11-year-old Chediak-Higashi syndrome (CHS)-affected cats were examined by light, fluorescence, and electron microscopy. Numerous round to oval bodies of various sizes were associated with the retinal pigment epithelium (RPE). These bodies stained positively with periodic acid-Schiff. They also displayed a bright yellow autofluorescence and stained positively with a prolonged Ziehl-Neelsen acid-fast method for demonstration of lipofuscin, suggesting that they contained lipofuscin or a lipofuscin-like material. Ultrastructural examination disclosed the bodies to be secondary lysosomes and large to giant-sized residual bodies. Many of the residual bodies were extracellular and formed drusen-like mounds, covered by deposits of basal lamina, beneath the RPE. Also evident were scattered degenerated RPE cells and other RPE cells that had detached and migrated into the interphotoreceptor space. The presence of drusenoid bodies, and the loss of cells from the RPE monolayer in CHS eyes have not been reported previously. Many of the changes in the CHS cat eyes resemble those in non-CHS aging eyes of man and other species.

Aberrant melanosome development in the retinal pigmented epithelium of cats with Chediak-Higashi syndrome.

The Chediak-Higashi syndrome is a genetic disorder characterized by greatly enlarged cytoplasmic granules, including lysosomes and melanosomes. Eyes of humans and animals with Chediak-Higashi syndrome are hypopigmented to various degrees. Intraocular melanin granules vary in size, with some being massively enlarged. Electron microscopic examination of retinal pigmented epithelium of kittens with Chediak-Higashi syndrome disclosed a number of abnormalities of premelanosomes and melanosomes. Few premelanosomes were present. Most of the melanin granules were giant sized, but their structures varied. Some of the giant granules were composed of several premelanosomes and melanosomes in different stages of maturation. Others contained randomly oriented melanofilaments between melanosomes. There were also complex giant granules consisting of both melanosomal and lysosomal components. Inappropriate fusion of cytoplasmic granules appears to be the most likely mechanism for formation of the giant granules. Fusion of premelanosomes with lysosomes and resultant destruction of the premelanosomes probably is a major cause of the ocular hypopigmentation of Chediak-Higashi syndrome.

Tapetal degeneration in cats with Chediak-Higashi syndrome.

The Chediak-Higashi syndrome (CHS) is a genetic disorder of man, cats, and four other animal species. Enlarged cytoplasmic granules, including lysosomes and melanosomes, characterize the syndrome. Cats affected with CHS lack funduscopically visible tapeta. In normal cats, the tapetum is the light reflecting cellular layer located in the choroid. The tapetal cells contain bundles of parallel cytoplasmic rods. In this study, eyes from CHS and control cats were examined by light microscopy and transmission electron microscopy. The CHS kittens up to 14 days of age had tapeta which appeared similar to those of the controls. By 28 days of age some of the CHS tapetal rods had degenerated. Degeneration of the tapetal rods progressed rapidly and by 56 days of age there was a dramatic difference in the ultrastructural appearance of the tapetal cells. All the rods had degenerated and the contents of the tapetal cells were disorganized. The tapetal layer gradually thinned over a period of several months until the layer was absent or nearly so in CHS cats over one year of age. This study demonstrated that there is a previously overlooked degenerative component of the Chediak-Higashi syndrome.

Ocular melanin pigmentation anomalies in cats, cattle, mink, and mice with Chediak-Higashi syndrome: histologic observations.

The Chediak-Higashi syndrome (CHS) is a hereditary disorder of man, with the homologous condition reported in five animal species. Multiple defects, including oculocutaneous hypopigmentation, are present in individuals with this syndrome. Giant cytoplasmic granules, including melanosomes and lysosomes, are characteristic. In this study, eyes from CHS affected and control cats, cattle, mink, and mice were examined histologically to determine: 1) degree of pigmentation; 2) structure and distribution of melanin granules; and 3) morphology of cells and tissues containing melanin. The CHS cattle were found to be the most ocularly hypopigmented species, whereas CHS mouse eyes contained considerably more melanin than those of the other species. Melanin granules of abnormal sizes and shapes were present in neuroepithelial and uveal tissues of CHS animals of all four species. Depigmentation apparently had occurred in the CHS eyes, since less melanin was present in eyes of old CHS animals of each species than was present in eyes of young animals. In addition, melanin containing macrophages were common in CHS eyes, and the numbers of melanocytes and pigmented epithelial cells were decreased in older CHS eyes.

A technique for preserving aerial fungal structures for scanning electron microscopy.

A technique is described that employs vapor fixation and a simple vapor diffusion dehydration apparatus to minimize the disturbance of delicate fungal structures during preparation for scanning electron microscopy. The technique is applicable to fungi grown on agar media or on natural substrates.

Studies on cell division in mammalian cells. VII. A temperature-sensitive cell line abnormal in centriole separation and chromosome movement.

A temperature-sensitive Syrian hamster mutant cell line, ts-745, exhibiting novel mitotic events has been isolated. The cells show normal growth and mitosis at 33 degrees C, the permissive temperature. At the nonpermissive temperature of 39 degrees C, mitotic progression becomes aberrant. Metaphase cells and those cells still able to form a metaphase configuration continue through and complete normal cell division. However, cells exposed to 39 degrees C for longer than 15 min can not form a normal metaphase spindle. Instead, the chromosomes are distributed in a spherical shell, with microtubules (MT) radiating to the chromosomes from four closely associated centrioles near the center of the cell. The cells progress from the spherical monopolar state to other monopolar orientations conical in appearance with four centrioles in the apex region. Organized chromosome movement is present, from the spherical shell state to the asymmetrical orientations. Chromosomes remain in the metaphase configuration without chromatid separation. Prometaphase chromosome congression appears normal, as the chromosomes and MT form a stable monopolar spindle, but bipolar spindle formation is apparently blocked in a premetaphase state. When returned from 39 degrees to 33 degrees C, the defective phenotype is readily reversible. At 39 degrees C, the mitotic abnormality lasts 3-5 h, followed by reformation of a single nucleus and cell flattening in an interphase-like state. Subsequent cell cycle events appear to occur, as the cells duplicate chromosomes and initiate a second round of abnormal mitosis. Cell cycle traversion continues for at least 5 d in some cells despite abnormal mitosis resulting in cells accumulating several hundred chromosomes.

Membranous glomerulopathy in a patient with sarcoidosis.

We describe a case of membranous nephropathy in a patient with pulmonary, splenic and hepatic sarcoidosis. The patient was asymptomatic, and edema was absent notwithstanding the proteinuria (over 8.0 gm/100 ml daily). Prednisone cleared the pulmonary and splenic complications, but the proteinuria, although diminished, persisted. Adjunctive therapy with cyclophosphamide caused further diminishment of the proteinuria. We have reviewed the relationship between the nephropathy and the sarcoidosis and suggest that a causal relationship exists between the two diseases.