Understanding the reaction mechanism of the oxidative addition of ammonia by (PXP)Ir(i) complexes: the role of the X group.

An analysis of the electronic rearrangements for the oxidative addition of ammonia to a set of five representative (PXP)Ir pincer complexes (X = B, CH, O, N, SiH) is performed. We aim to understand the factors controlling the activation and reaction energies of this process by combining different theoretical strategies based on DFT calculations. Interestingly, complexes featuring higher activation barriers yield more exothermic reactions. The analysis of the reaction path using the bonding evolution theory shows that the main chemical events, N-H bond cleavage and Ir-H bond formation, take place before the transition structure is reached. Metal oxidation implies an electron density transfer from non-shared Ir pairs to the Ir-N bond. This decrement in the atomic charge of the metal provokes different effects in the ionic contribution of the Ir-X bonding depending on the nature of the X atom as shown by the interacting quantum atoms methodology.

Mobility and postural limitations perceived by transtibial amputees undertaking agricultural activities: a qualitative study.

PURPOSE: In Colombia, 98% of landmines occur in rural areas, where the main victims of amputation are farmers. The challenges these amputees face in their agricultural work remain unknown. The aim of this study is to determine the mobility and postural limitations these farmers face in carrying out their daily activities. METHOD: Forty-nine participants meeting the following criteria were interviewed: transtibial amputee, 18 years and over, performs agricultural labour and wears the prosthesis daily. Subsequently, the interview transcripts were subjected to a content conventional analysis and responses were organized according to the abstraction process to identify categories and subcategories of the problems. RESULTS: Main problems reported were walking on sloping, uneven and wet terrain, problems associated with the stump skin, squatting, kneeling, using vehicles or animals for transportation and carrying objects over 30 kg. Postures such as sitting, running, jumping, and standing on tiptoes were mentioned less frequently. CONCLUSIONS: In conclusion, the prostheses worn by transtibial amputee farmers are not suitable for working on sloping and uneven terrain, nor for performing postures such as kneeling or squatting. These postures are very common in agricultural and livestock tasks in countries with mountainous areas such as Latin American countries. The recognition of problems reported by farmers transtibial amputees, may help to improve the design of prostheses so that they meet the needs of this population and decrease secondary injuries associated with prosthetic use. This information is useful to identify compensatory postures that facilitate prosthetic adaptation and rehabilitation for amputees.

The apoptotic v-cyclin-CDK6 complex phosphorylates and inactivates Bcl-2.

v-cyclin encoded by Kaposi's sarcoma herpesvirus/human herpesvirus 8 (KSHV or HHV8) associates with cellular cyclin-dependent kinase 6 (CDK6) to form a kinase complex that promotes cell-cycle progression, but can also induce apoptosis in cells with high levels of CDK6. Here we show that whereas HHV8-encoded v-Bcl-2 protects against this apoptosis, cellular Bcl-2 has lost its anti-apoptotic potential as a result of an inactivating phosphorylation in its unstructured loop region. Moreover, we identify Bcl-2 as a new substrate for v-cyclin-CDK6 in vitro, and show that it is present in a complex with CDK6 in cell lysates. A Bcl-2 mutant with a S70A S87A double substitution in the loop region is not phosphorylated and provides resistance to apoptosis, indicating that inactivation of Bcl-2 by v-cyclin-CDK6 may be required for the observed apoptosis. Furthermore, the identification of phosphorylated Bcl-2 in HHV8-positive Kaposi's sarcoma indicates that HHV8-mediated interference with host apoptotic signalling pathways may encourage the development of Kaposi's sarcoma.

Modulation of gut immune response by probiotic fermented milk consumption to control IgE in a respiratory allergy model.

Allergies are a world increasing health issue and most treatments are oriented to alleviate symptoms. Probiotics have several health benefits including the improvement of the immune system. In previous work we found that consumption of commercial probiotic fermented milk (PFM) significantly reduced specific-immunoglobulin (Ig) E in serum and lungs by increasing specific-IgG and controlled allergic response to ovalbumin (OVA) in an adult mouse respiratory allergy model. Here we continued our study determining the mechanism triggered in the gut by the PFM ingestion that influenced the results previously reported. Five groups of BALB/c mice were assessed: normal-control, basal (drinks PFM five days without OVA sensitisation), sensitisation-control (no PFM intake), previous and continuous-PFM administration. Allergen administration: 3 OVA injections (1% in PBS) followed by aerosols exposure for 7 days. We determined total secretory-IgA and cytokines in small intestine (SI) fluid; CD11b+, CD103+, IgA+ cells and cytokine producing cells in SI tissue. In lungs we analysed co-expression of CD4/interferon (IFN)-γ or CD4/interleukin (IL)-10, IgE+ cells and IL-12 production. Results: continuous intake of PFM increased the expression of CD103 marker and decreased CD11b and pro-inflammatory cytokines. Coexpression of CD4/IFN-γ was confirmed in lungs of animals that consumed PFM continuously. This group had a lower count of IgE+ cells and a higher concentration of IL-12. The consumption of PFM reinforces the mucosal barrier by increasing IgA+ cells and induces signalling from the intestine to the lungs by increasing the expression of CD103+ dendritic cells related to regulatory mechanisms. The results found in this work together with those previously reported demonstrated that the intake of PFM induces a clear balance towards the Th1 response, preventing the Th2 allergic response by controlling the previously reported IgE level. According to our model, the intake of PFM could be a good strategy to alleviate the development of allergies.

Use of a Gemini-Surfactant Synthesized from the Mango Seed Oil as a CO2-Corrosion Inhibitor for X-120 Steel.

A gemini surfactant imidazoline type, namely N-(3-(2-fatty-4,5-dihydro-1H-imidazol-1-yl) propyl) fatty amide, has been obtained from the fatty acids contained in the mango seed and used as a CO2 corrosion inhibitor for API X-120 pipeline steel. Employed techniques involved potentiodynamic polarization curves, linear polarization resistance, and electrochemical impedance spectroscopy. These tests were supported by detailed scanning electronic microscopy (SEM) and Raman spectroscopy studies. It was found that obtained gemini surfactant greatly decreases the steel corrosion rate by retarding both anodic and cathodic electrochemical reactions, with an efficiency that increases with an increase in its concentration. Gemini surfactant inhibits the corrosion of steel by the adsorption mechanism, and it is adsorbed on to the steel surface according to a Langmuir model in a chemical type of adsorption. SEM and Raman results shown the presence of the inhibitor on the steel surface.

Respiratory allergy control by probiotic fermented milk intake: a mouse model from weaning to maturity.

This study is based on our previous research showing that commercial probiotic fermented milk (PFM) intake mitigates respiratory allergy development to ovalbumin (OVA) in adult mice (6-weeks old) increasing specific immunoglobulin (Ig)G2a and interferon (IFN)-γ rather than IgE. The aim was to determine if PFM exerts a protective effect when an allergy model is induced 5 days after weaning and whether the mechanisms involved are similar to those previously reported. Before inducing allergy, a group of 21-day old BALB/c mice received PFM for 10 days to analyse the impact on intestinal epithelial cells (IECs) activation. Two more groups received PFM for 5 days and were sensitised with OVA; only one group continued taking PFM until the end of the experiment. Sensitisation scheme: 3 OVA injections 1% in phosphate buffered saline (PBS) plus 7 days OVA aerosol exposure and re-stimulus 15 days later. The contents of specific- IgE, IgG, total-secretory-IgA and Th1/Th2 balance in serum, bronchoalveolar lavage (BAL) and gut were measured at 7 and 15 days post-sensitisation (dPS) and 2 days post-re-stimulus (2dPR). Treg cells in lungs were also quantified. Results were compared with normal and sensitised controls. PFM induced mild activation of IECs increasing monocyte chemoattractant protein-1 (MCP-1 or CCL2) and interleukin (IL)-6 production. In sensitised mice, PFM controlled the response inducing IgG rather than IgE at 7 and 15-dPS and 2dPR (60 days old). Th1-balance (IFN-γ) was favoured by PFM in lungs at 7 dPS with low levels of IL-10 released to regulate the response. Total-S-IgA increased in lungs and gut; however, PFM intake did not affect Treg cells in lungs. PFM maintains controlled stimulation of the immune cells involved in Th1 response, favouring IgG at the respiratory mucosal site. Although the effect was not as strong as that reported previously, PFM promoted maturation and activation of gut immune cells preserving intestinal homeostasis and lung immune response.

Imaging of the muscle and bone from benchtop to bedside.

Studies have begun to show that muscles and bones play a role in the regulation of biological functions through a combination of biomechanical and biochemical signals. In vivo and ex vivo imaging techniques are crucial in the understanding of the morphology and architecture of muscle and bone for further understanding of musculoskeletal physiology and pathophysiology. This systematic review of the literature summarizes current knowledge and outlines new insights into the functions of muscle and bone elucidated by imaging techniques, with a focus on the recent advances in the musculoskeletal system enabled by novel technologies, such as CLARITY, Fast Free-of-Acrylamide Clearing Tissue (FACT), computed tomography (CT), and positron emission tomography (PET). This may serve as guidance for the development of new strategies to prevent and diagnose motor or metabolism disorders related to the malfunction of muscle and bone.

Regulatory mechanisms involved in muscle and bone remodeling during refeeding in gilthead sea bream.

The tolerance of fish to fasting offers a model to study the regulatory mechanisms and changes produced when feeding is restored. Gilthead sea bream juveniles were exposed to a 21-days fasting period followed by 2 h to 7-days refeeding. Fasting provoked a decrease in body weight, somatic indexes, and muscle gene expression of members of the Gh/Igf system, signaling molecules (akt, tor and downstream effectors), proliferation marker pcna, myogenic regulatory factors, myostatin, and proteolytic molecules such as cathepsins or calpains, while most ubiquitin-proteasome system members increased or remained stable. In bone, downregulated expression of Gh/Igf members and osteogenic factors was observed, whereas expression of the osteoclastic marker ctsk was increased. Refeeding recovered the expression of Gh/Igf system, myogenic and osteogenic factors in a sequence similar to that of development. Akt and Tor phosphorylation raised at 2 and 5 h post-refeeding, much faster than its gene expression increased, which occurred at day 7. The expression in bone and muscle of the inhibitor myostatin (mstn2) showed an inverse profile suggesting an inter-organ coordination that needs to be further explored in fish. Overall, this study provides new information on the molecules involved in the musculoskeletal system remodeling during the early stages of refeeding in fish.

Biological and Cognitive Markers of Presenilin1 E280A Autosomal Dominant Alzheimer's Disease: A Comprehensive Review of the Colombian Kindred.

The study of individuals with autosomal dominant Alzheimer's disease affords one of the best opportunities to characterize the biological and cognitive changes of Alzheimer's disease that occur over the course of the preclinical and symptomatic stages. Unifying the knowledge gained from the past three decades of research in the world's largest single-mutation autosomal dominant Alzheimer's disease kindred - a family in Antioquia, Colombia with the E280A mutation in the Presenilin1 gene - will provide new directions for Alzheimer's research and a framework for generalizing the findings from this cohort to the more common sporadic form of Alzheimer's disease. As this specific mutation is virtually 100% penetrant for the development of the disease by midlife, we use a previously defined median age of onset for mild cognitive impairment for this cohort to examine the trajectory of the biological and cognitive markers of the disease as a function of the carriers' estimated years to clinical onset. Studies from this cohort suggest that structural and functional brain abnormalities - such as cortical thinning and hyperactivation in memory networks - as well as differences in biofluid and in vivo measurements of Alzheimer's-related pathological proteins distinguish Presenilin1 E280A mutation carriers from non-carriers as early as childhood, or approximately three decades before the median age of onset of clinical symptoms. We conclude our review with discussion on future directions for Alzheimer's disease research, with specific emphasis on ways to design studies that compare the generalizability of research in autosomal dominant Alzheimer's disease to the larger sporadic Alzheimer's disease population.

Nitrogen doped carbon dots derived from Sargassum fluitans as fluorophore for DNA detection.

This work focused on the use of waste seaweed Sargassum fluitans (S. fluitans) as carbon source precursor to prepare nitrogen doped carbon dots (NCDs) by hydrothermal method. High resolution transmission electron microscopic (HR-TEM) studies revealed that the synthesized water soluble NCDs are in the size range of 2-8nm and exhibits excellent fluorescent properties with a quantum yield of 18.2%. Elemental nitrogen in NCDs was evidenced by X-ray photoelectron spectroscopy (XPS) and Fourier transformed infrared spectrum (FT-IR). The phytochemical analysis of S. fluitans using 1H NMR and 13C NMR revealed the presence of few amino acids which act as nitrogen source in the preparation of NCDs. Application of NCDs as fluorophore for double stranded DNA, single stranded DNA and RNA detection was highlighted in this study. Excellent fluorescent tagging abilities of NCDs with the biological nucleic acids were evidenced using gel electrophoresis. Significant increase in fluorescence was observed upon tagging of NCDs with nucleic acids and this particular phenomenon helps better in visualizing the nucleic acids. All three nucleic acids i.e. double stranded DNA, single stranded DNA and RNA showed similar phenomenon upon tagging with NCDs. Thus synthesized NCDs may be used as an alternate fluorophore for commercial toxic organic staining agents to visualize nucleic acids.

Expression of K13/v-FLIP gene of human herpesvirus 8 and apoptosis in Kaposi's sarcoma spindle cells.

BACKGROUND: Human herpesvirus 8 (HHV8) infection is associated with all forms of Kaposi's sarcoma (KS). The HHV8 genome locus ORFK13-72-73 (ORF = open reading frame) encodes proteins that may be important in HHV8-mediated pathogenesis, i.e., the latency-associated nuclear antigen (encoded by ORF73), viral-cyc-D (v-cyc-D), a viral homologue of cellular cyclin D (encoded by ORF72), and viral-FLIP (v-FLIP), a homologue of the cellular FLICE (Fas-associated death domain-like interleukin 1 beta-converting enzyme) inhibitory protein (encoded by ORFK13; is an inhibitor of apoptosis [programmed cell death]). Through differential splicing events, this locus expresses individual RNA transcripts that encode all three proteins (tricistronic transcripts) or just two of them (v-FLIP and v-cyc-D; bicistronic transcripts). We examined expression of these transcripts in KS tissues. METHODS: We collected tissues from patients with KS of different stages. By use of an optimized in situ hybridization procedure, we examined different ORFK13-72-73 locus transcripts in HHV8-infected cells in skin lesions and in one adjacent lymph node. Apoptosis in KS lesions was determined by use of an in situ assay. RESULTS AND CONCLUSIONS: Our results indicate the following: 1) Transcripts from the ORFK13-72-73 locus appear to be spliced differentially in latently infected KS cells in skin lesions and in HHV8-infected cells in lymph nodes; specifically, ORFK13-ORF72 bicistronic transcripts were expressed abundantly in KS cells, whereas ORFK13-ORF72-ORF73 tricistronic transcripts were detected only in lymph node cells. 2) Sequences encoding the antiapoptotic protein v-FLIP are expressed at very low levels in early KS lesions, but expression increases dramatically in late-stage lesions. 3) The increase in expression of v-FLIP-encoding transcripts is associated with a reduction in apoptosis in KS lesions. IMPLICATIONS: These data suggest that functional v-FLIP is produced in vivo and that antiapoptotic mechanisms may be involved in the rapid growth of KS lesions, where only a few cells undergoing mitosis are generally observed.

Meaning of illness and illness representations, crucial factors to integral care.

INTRODUCTION: A comprehensive study of end-stage renal disease (ESRD) and haemodialysis (HD) must include the sociocultural dimension of illness and the experience of patients from their own perspective. It is critical for the caring team to know how the disease is lived and reinterpreted by the patient, as this knowledge could improve nursing staff/patient interaction. The meaning of their experience is also an influential factor on the caring methods utilised by the patient. FRAMEWORK: The Theory of Representations and Explanatory Model of Illness was utilised in the study. METHODOLOGY: A narrative qualitative methodology, grounded in a constructivist paradigm was used. Twelve patients were interviewed. The interviews were audio taped and transcribed verbatim. RESULTS: Results revealed that patients have a range of beliefs about their illness and their treatment. Regarding identity, symptoms that arise at the outset of illness are not suspected of relating to renal failure. The inevitability of haemodialysis convinces patients of the presence of illness, opening a wide range of metaphors and symbolic representations. CONCLUSIONS: Representations of ESRD and HD conform to a multidimensional corpus where different elements of scientific order and common sense converge and interact, such as beliefs and fears. All of these contribute to the meaning of this illness and its treatment. The attributed meaning is dynamic being continually elaborated based on illness outcomes, adaptation to treatment, particular events and the sociocultural environment.

Kaposi's sarcoma-associated herpesvirus-encoded v-cyclin triggers apoptosis in cells with high levels of cyclin-dependent kinase 6.

Kaposi's sarcoma-associated herpesvirus (KSHV) has a key etiological role in development of Kaposi's sarcoma (KS). v-Cyclin is a KSHV-encoded homologue to D-type cyclins that associates with cellular cyclin-dependent kinase 6 (CDK6). v-Cyclin promotes S-phase entry of quiescent cells and has been suggested to execute functions of both D- and E-type cyclins. In this study, expression of v-cyclin in cells with elevated levels of CDK6 led to apoptotic cell death after the cells entered S phase. The cell death required the kinase activity of CDK6 because cells expressing a kinase-deficient form of CDK6 did not undergo apoptosis upon v-cyclin expression. Studies on the mechanisms involved in this caspase-3-mediated apoptosis indicated that it was independent of cellular p53 or pRb status, and it was not suppressed by Bcl-2. In contrast, the KSHV-encoded v-Bcl-2 efficiently suppressed v-cyclin-/CDK6-induced apoptosis, demonstrating a marked difference in the antiapoptotic properties of c-Bcl-2 and v-Bcl-2. In KS lesions, high CDK6 expression was confined to a subset of cells, some of which displayed signs of apoptosis. These results suggest that v-cyclin may exert both growth-promoting and apoptotic functions in KS, depending on factors regulating CDK6 and v-Bcl-2 levels.

Growth-promoting effects of sustained swimming in fingerlings of gilthead sea bream (Sparus aurata L.).

Fish growth is strongly influenced by environmental and nutritional factors and changing culture conditions can help optimize it. The importance of early-life experience on the muscle phenotype later in life is well known. Here, we study the effects of 5 weeks of moderate and sustained swimming activity (5 BL s(-1)) in gilthead sea bream during early development. We analysed growth and body indexes, plasma IGF-I and GH levels, feed conversion, composition [proximate and isotopic ((15)N/(13)C)] and metabolic key enzymes (COX, CS, LDH, HOAD, HK, ALAT, ASAT) of white muscle. Moderate and continuous exercise in fingerlings of gilthead sea bream increased plasma IGF-I, whereas it reduced plasma GH. Under these conditions, growth rate improved without any modification to feed intake through an increase in muscle mass and a reduction in mesenteric fat deposits. There were no changes in the content and turnover of muscle proteins and lipid reserves. Glycogen stores were maintained, but glycogen turnover was higher in white muscle of exercised fish. A lower LDH/CS ratio demonstrated an improvement in the aerobic capacity of white muscle, while a reduction in the COX/CS ratio possibly indicated a functional adaptation of mitochondria to adjust to the tissue-specific energy demand and metabolic fuel availability in exercised fish. We discuss the synergistic effects of dietary nutrients and sustained exercise on the different mitochondrial responses.

Vasopressin messenger ribonucleic acid regulation via the protein kinase A pathway.

Activation of vasopressin (VP) gene expression in vivo by osmotic stimuli results in an increase in both messenger RNA (mRNA) content and polyadenylate [poly(A)] tail length. VP gene transcription in vitro is stimulated by protein kinase A (PKA) activation. To examine the role of PKA in the regulation of VP mRNA poly(A) metabolism, constructs of the rat VP gene were permanently transfected into the mouse anterior pituitary cell line, AtT-20. Treatment with forskolin of cells expressing the intact VP gene resulted in increased VP gene transcription, an increase in the content of VP mRNA, and a shift toward VP mRNA species with longer poly(A) tails accompanied by the loss of VP mRNA species with shorter poly(A) tails. We uncoupled the PKA-stimulated appearance of long-tailed species from the disappearance of short-tailed species, suggesting that the size shift was caused by a coincident, but uncoupled net increase in VP mRNA species with elongated poly(A) tails and net loss of mRNA species with short poly(A) tails. These data indicate that activation of the PKA second-messenger pathway both enhances transcription of the VP gene and causes an increase in the average length of VP mRNA poly(A) tails. This latter effect, by shifting upwards the average poly(A) tail size, could result in increased translational efficiency or stability of VP mRNA, thereby providing an additional mechanism by which PKA may enhance gene expression.

Fetal porcine islet-like cell clusters transplanted to cynomolgus monkeys: an immunohistochemical study.

BACKGROUND: The mechanism(s) involved in acute cellular xenograft rejection have hitherto been generated in vitro or in different experimental models, with pig tissue being transplanted to rodents. There is an urgent need to validate these results in a clinically more relevant combination of species. METHODS: Fetal porcine islet-like cell clusters (ICC) were transplanted under the kidney capsule in cynomolgus monkeys, either untreated or given immunosuppression with cyclosporine (CsA; 10 mg/kg body weight, intramuscularly) and 15-deoxyspergualin (DSG; 5 mg/kg body weight, intramuscularly). ICC xenografts were examined at 1, 3, 6, or 10-12 days after transplantation, using immunohistochemical techniques. Serum levels of xenoreactive antibodies were measured with ELISA. RESULTS: No deposits of IgM, IgG, Clq, or C3 were detected within the ICC xenograft in any of the monkeys. Likewise, no significant increase in the levels of xenoreactive antibodies were found after transplantation. In untreated animals, a few N-Elastase-positive cells (neutrophil granulocytes) were seen in the xenograft at day 1. A few mononuclear cells were present in the adjacent renal parenchyma, but they did not infiltrate the xenograft. At this time (day 1), early signs of necrosis were observed in the central parts of the graft. On day 3, the graft had a large, central necrotic area that contained polymorphonuclear cells; the remaining parts of the xenograft showed severe infiltration with CD8+ T cells. Occasional CD68+ cells (macrophages) were seen on days 1 and 3. On day 6, large numbers of macrophages were found infiltrating the entire graft. A few CD20+ B cells, accumulated as small clusters, were also found. Only a few natural killer cells (CD56+) were detected. The CsA/DSG-treated monkeys showed markedly fewer CD2+/CD8+ T cells on day 6 than the untreated monkeys, and the ICC graft was clearly better preserved. However, the number of CD8+ and CD68+ cells had increased considerably at 12 days after transplantation and diffusely infiltrated the whole ICC xenograft. CONCLUSION: Porcine ICC transplanted under the kidney capsule in cynomolgus monkeys were rejected by an acute cell-mediated rejection progressing during the first 6 days after transplantation. The process was not dependent on host Ig or C3 binding to the graft. Although the rejection of porcine ICC was significantly delayed in CsA/DSG-treated monkeys, the ICC xenografts were almost completely destroyed 12 days after transplantation.

Role of nitric oxide in resistance and histopathology during experimental infection with Trypanosoma cruzi.

We analyzed the biological role of nitric oxide (NO) during murine Trypanosoma cruzi infection. Infection of mice with T. cruzi markedly increased NO synthesis. Administration of N-nitro-L-arginine methyl-esther (L-NAME) intraperitoneally or intragastrically diminished endogenous NO synthesis and resistance of mice to acute infection with three biologically different strains of T. cruzi. Mice protected against challenge with T. cruzi by transfer of T-cell-enriched populations from chronically infected animals, showed higher serum nitrate levels than controls non-transferred, or transferred, with T cells from non-immune mice. Administration of L-NAME abrogated transfer of resistance, suggesting NO participation in this process. Depletion of T cells from the transferred population abolished both protection and NO3- increase. On the contrary, mice chronically infected with T. cruzi showed no increased parasitemia or death upon treatment with L-NAME. The NO donor drug S-nitroso-acetyl-penicillamine was able to kill tissue culture or bloodstream trypomastigotes in vitro at biologically relevant concentrations. Conversely, NO appeared not to play a role in formation of inflammatory foci during T. cruzi infection, since infected mice treated with L-NAME showed no reduced inflammation.

Protection against mucosal SIVsm challenge in macaques infected with a chimeric SIV that expresses HIV type 1 envelope.

In a monkey model we used a chimeric SIV expressing the HIV-1 envelope gene (SHIV-4) as a live attenuated vaccine and a virulent SIVsm as a mucosal challenge. Four cynomolgus monkeys were inoculated intravenously with SHIV-4. Virus was repeatedly isolated from blood mononuclear cells of all four animals for 2 to 7 months after the inoculation of SHIV. All monkeys developed neutralizing antibodies to HIV-1 and high antibody titers to HIV-1 envelope glycoproteins. In contrast, no neutralizing antibodies to SIVsm were detected and cross-reacting antibodies to SIV envelope glycoproteins were demonstrable in low titers. Nine to 12 months after the SHIV inoculation the four monkeys and six naive control monkeys were challenged intrarectally with 10 monkey infectious doses of macaque cell-grown SIVsm. After a follow-up period of 1 year, two of four SHIV-infected monkeys were completely protected against SIVsm infection as shown by repeated negative virus isolations and negative polymerase chain reaction for SIV envelope DNA. One naive monkey that received blood from the two protected monkeys showed no signs of infection. The remaining two SHIV-infected monkeys showed an initial infection on challenge with SIVsm, but viral replication was thereafter suppressed. Cytotoxic T lymphocytes to SIV Nef and RT were demonstrable in one of four SHIV-infected monkeys before SIVsm challenge, but this monkey was not protected against SIV infection. All six control animals yielded virus repeatedly after SIVsm challenge and three of them showed declining CD4 cell counts. Thus, infection with SHIV expressing HIV-1 envelope could induce cross-protection against mucosal SIVsm challenge.

Measles virus antigen in macrophage/microglial cells and astrocytes of subacute sclerosing panencephalitis.

In two patients with subacute sclerosing panencephalitis (SSPE) of 10 and 25 months duration we demonstrated by immunohistochemistry the presence of measles-virus nucleocapsid antigen (MVNA) in CD68+ cells and astrocytes of brain tissues. In both cases, CD68+ hematogenous monocyte/ macrophages and perivascular microglial cells (Mphi) were found infiltrating the brain parenchyma, and often partially or completely invested by perivascular reactive astrocytes expressing glial fibrillary acidic protein (GFAP). Mphi with cytoplasmic MVNA were often seen in the Virchow-Robin spaces and in close association with perivascular astrocytes, which often also contained MVNA+ intracytoplasmic inclusions. Reactive astrocytosis was more severe in the patient with long-standing illness, and a correspondingly elevated number of strongly GFAP+ MVNA+ or MVNA- perivascular binucleated astrocytes was observed. An uptake of MVNA+ cell debris by reactive astrocytes was evident in areas of white matter displaying extensive demyelination and necrosis. Taken together, these observations seem to indicate that the brain infiltration by Mphi carrying measles virus could represent one pathway of virus entry and dissemination in the central nervous system. Virus transfer to perivascular astrocytes via cell-to-cell contacts with infected macrophages is also suggested.

Geometric ray tracing analysis of visual acuity after laser in situ keratomileusis.

PURPOSE: Using a geometric ray tracing model, we explain the increase in visual acuity observed in myopic patients after laser in situ keratomileusis (LASIK). METHODS: This study included 37 eyes of 23 patients who underwent LASIK. All patients had myopia and a spectacle-corrected visual acuity of 0.95 or worse. Clinical tests included biometry, corneal topography, pachymetry, and refraction (with and without cycloplegia). Calculations were made by tracing rays through all the refractive surfaces of the eye based on a Le Grand-type theoretical model of the whole eye. RESULTS: Comparison of spectacle-corrected visual acuity of the eye before surgery, the size of the blur circle calculated by ray tracing, and the magnification for the ocular system facilitated a numerical criterion to assess visual acuity by geometric calculation. This criterion was applied to myopic eyes that underwent LASIK, and the maximum increase in spectacle-corrected visual acuity was predicted. An actual increase in visual acuity of approximately 40% of the predicted maximum was observed in patients. CONCLUSIONS: With geometric ray tracing, it was possible not only to obtain an estimate of the visual acuity before LASIK but also to assess the value of the maximum and probable increases in visual acuity after LASIK.