Is the Differentiated Service Delivery Model Suited to the Needs of People Living with HIV in Rwanda?

The primary goal of antiretroviral treatment is to improve the health of individuals with HIV, and a secondary goal is to prevent further transmission. In 2016, Rwanda adopted the World Health Organization's "treat-all" approach in combination with the differentiated service delivery (DSD) model. The model's goal was to shorten the time from HIV diagnosis to treatment initiation, regardless of the CD4 T-cell count. This study sought to identify perceptions, enablers, and challenges associated with DSD model adoption among PLHIV.This study included selected health centers in Kigali city, Rwanda, between August and September 2022. The patients included were those exposed to the new HIV care model (DSD) model and those exposed to the previous model who transitioned to the current model. Interviews and focus group discussions were also held to obtain views and opinions on the DSD model. The data were collected via questionnaires and audio-recorded focus group discussions and were subsequently analyzed.The study identified several themes, including participants' initial emotions about a new HIV diagnosis, disclosure, experiences with transitioning to the DSD model, the effect of peer education, and barriers to and facilitators of the DSD model. Participants appreciated reduced clinic visits under the DSD model but faced transition and peer educator mobility challenges.The DSD model reduces waiting times, educates patients, and aligns with national goals. Identified barriers call for training and improved peer educator retention. Recommendations include enhancing the DSD model and future research to evaluate its long-term impact and cost-effectiveness.

Cryofixation during live-imaging enables millisecond time-correlated light and electron microscopy.

Correlating live-cell imaging with electron microscopy is among the most promising approaches to relate dynamic functions of cells or small organisms to their underlying ultrastructure. The time correlation between light and electron micrographs, however, is limited by the sample handling and fixation required for electron microscopy. Current cryofixation methods require a sample transfer step from the light microscope to a dedicated instrument for cryofixation. This transfer step introduces a time lapse of one second or more between live imaging and the fixed state, which is studied by electron microscopy. In this work, we cryofix Caenorhabditis elegans directly within the light microscope field of view, enabling millisecond time-correlated live imaging and electron microscopy. With our approach, the time-correlation is limited only by the sample cooling rate. C. elegans was used as a model system to establish compatibility of in situ cryofixation and subsequent transmission electron microscopy (TEM). TEM images of in situ cryofixed C. elegans show that the ultrastructure of the sample was well preserved with this method. We expect that the ability to correlate live imaging and electron microscopy at the millisecond scale will enable new paradigms to study biological processes across length scales based on real-time selection and arrest of a desired state. LAY DESCRIPTION: Researchers seek to link cellular functions to their smallest structural components. Currently this requires correlation of two imaging techniques, live imaging and electron microscopy. Current correlative methods, however, have limited time resolution due to the sample preparation procedures for electron microscopy. Following live imaging, samples are transferred from the light microscope to a cryofixation, or ultra-fast freezing, instrument. The biological process progresses until the sample freezes, 1 second or more after the last live image. In this work, samples are cryofixed directly within the light microscope field of view. By eliminating the transfer step, time correlation between light and electron microscopy images of our samples is limited only by the freezing rate to the order of milliseconds rather than seconds.

Resonant addressing and manipulation of silicon vacancy qubits in silicon carbide.

Several systems in the solid state have been suggested as promising candidates for spin-based quantum information processing. In spite of significant progress during the last decade, there is a search for new systems with higher potential [D. DiVincenzo, Nat. Mater. 9, 468 (2010)]. We report that silicon vacancy defects in silicon carbide comprise the technological advantages of semiconductor quantum dots and the unique spin properties of the nitrogen-vacancy defects in diamond. Similar to atoms, the silicon vacancy qubits can be controlled under the double radio-optical resonance conditions, allowing for their selective addressing and manipulation. Furthermore, we reveal their long spin memory using pulsed magnetic resonance technique. All these results make silicon vacancy defects in silicon carbide very attractive for quantum applications.

Synaptic vesicles studied by dynamic light scattering.

The size polydispersity distribution of synaptic vesicles (SVs) is characterized under quasi-physiological conditions by dynamic light scattering (DLS). Highly purified fractions of SVs obtained from rat brain still contain a small amount of larger contaminant structures, which can be quantified by DLS and further reduced by asymmetric-flow field-flow (AFFF) fractionation. The intensity autocorrelation functions g (2)(τ) recorded from these samples are analyzed by a constrained regularization method as well as by an alternative direct modeling approach. The results are in quantitative agreement with the polydispersity obtained from cryogenic electron microscopy of vitrified SVs. Next, different vesicle fusion assays based on samples composed of SVs and small unilamellar proteoliposomes with the fusion proteins syntaxin 1 and SNAP-25A are characterized by DLS. The size increase of the proteoliposomes due to SNARE-dependent fusion with SVs is quantified by DLS under quasi-physiological conditions.

Nonlocal activation of a bistable atom through a surface state charge-transfer process on Si(100)-(2×1):H.

The reversible hopping of a bistable atom on the Si(100)-(2×1):H surface is activated nonlocally by hole injection into Si-Si bond surface states with a low temperature (5 K) scanning tunneling microscope. In the contact region, at short distances (<1.5 nm) between the hole injection site and the bistable atom, the hopping yield of the bistable atom exhibits remarkable variations as a function of the hole injection site. It is explained by the density of state distribution along the silicon bond network that shows charge-transfer pathways between the injection sites and the bistable atom.

A cell-free system for regulated exocytosis in PC12 cells.

We have developed a cell-free system for regulated exocytosis in the PC12 neuroendocrine cell line. Secretory vesicles were preloaded with acridine orange in intact cells, and the cells were sonicated to produce flat, carrier-supported plasma membrane patches with attached vesicles. Exocytosis resulted in the release of acridine orange which was visible as a disappearance of labeled vesicles and, under optimal conditions, produced light flashes by fluorescence dequenching. Exocytosis in vitro requires cytosol and Ca(2+) at concentrations in the micromolar range, and is sensitive to Tetanus toxin. Imaging of membrane patches at diffraction- limited resolution revealed that 42% of docked granules were released in a Ca(2+)-dependent manner during 1 min of stimulation. Electron microscopy of membrane patches confirmed the presence of dense-core vesicles. Imaging of membrane patches by atomic force microscopy revealed the presence of numerous particles attached to the membrane patches which decreased in number upon stimulation. Thus, exocytotic membrane fusion of single vesicles can be monitored with high temporal and spatial resolution, while providing access to the site of exocytosis for biochemical and molecular tools.

Quantal release of serotonin.

We have studied the origin of quantal variability for small synaptic vesicles (SSVs) and large dense-cored vesicles (LDCVs). As a model, we used serotonergic Retzius neurons of leech that allow for combined amperometrical and morphological analyses of quantal transmitter release. We find that the transmitter amount released by a SSV varies proportionally to the volume of the vesicle, suggesting that serotonin is stored at a constant intravesicular concentration and is completely discharged during exocytosis. Transmitter discharge from LDCVs shows a higher degree of variability than is expected from their size distribution, and bulk release from LDCVs is slower than release from SSVs. On average, differences in the transmitter amount released from SSVs and LDCVs are proportional to the size differences of the organelles, suggesting that transmitter is stored at similar concentrations in SSVs and LDCVs.

Fluorescence nanoscopy with optical sectioning by two-photon induced molecular switching using continuous-wave lasers.

During the last decade far-field fluorescence microscopy methods have evolved that have resolution far below the wavelength of light. To outperform the limiting role of diffraction, all these methods, in one way or another, switch the ability of a molecule to emit fluorescence. Here we present a novel rhodamine amide that can be photoswitched from a nonfluorescent to a fluorescent state by absorption of one or two photons from a continuous-wave laser beam. This bright marker enables strict control of on/off switching and provides single-molecule localization precision down to 15 nm in the focal plane. Two-photon induced nonlinear photoswitching of this marker with continuous-wave illumination offers optical sectioning with simple laser equipment. Future synthesis of similar compounds holds great promise for cost-effective fluorescence nanoscopy with noninvasive optical sectioning.

Rhodotorula glutinis fungemia in a liver-kidney transplant patient.

A 54-year-old man underwent simultaneous liver-kidney transplantation. During his prolonged hospitalization, he developed catheter-related fungemia with Rhodotorula glutinis and azole-resistant Candida glabrata. Management of the Rhodotorula fungemia was complicated by his renal insufficiency, hepatic insufficiency, and the concurrent fungemia with multi-azole resistant C. glabrata. He was treated with combination therapy with voriconazole and micafungin with subsequent clearance of the fungemia. Rhodotorula species are emerging as human pathogens with the increasing number of immunosuppressed patients in the last few decades. This is the first report of a R. glutinis fungemia in a solid organ transplant recipient.

Granulocyte-macrophage colony-stimulating factor induces cytokine secretion by human polymorphonuclear leukocytes.

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is known as an inducer of proliferation and functional activation of myeloid cells. This study was carried out to characterize the effects of GM-CSF on polymorphonuclear leukocytes (PMN) more extensively. Using Northern blot analysis, we show that PMN are able to accumulate mRNAs for different cytokines, including tumor necrosis factor-alpha (TNF-alpha); G-CSF, and M-CSF, all of which are involved in inflammation and hematopoiesis. Biological assays and immunoassays demonstrate that PMN translate these mRNAs, except TNF-alpha, into secretory proteins. However, the expression of these cytokines is dependent on stimulation by exogenous signals, preferentially provided by the T cell-derived lymphokine GM-CSF. Stimulation of hematopoiesis and amplification of defense mechanisms after T cell activation thus might involve not only monocytes but also PMN, a cell type previously believed to be biosynthetically inactive.

Mortality study of Canadian male farm operators: non-Hodgkin's lymphoma mortality and agricultural practices in Saskatchewan.

A cohort study of the mortality experience (1971-1985) of male Saskatchewan farmers has been conducted. This study involved linkage of records of the almost 70,000 male farmers identified on the 1971 Census of Agriculture and the corresponding Census of Population to mortality records. Pesticide exposure indices for individual farm operators for the year 1970 were derived from the 1971 Census of Agriculture records. Although the cohort as a whole had no excess mortality for any specific causes of death, including non-Hodgkin's lymphoma, significant dose-response relationships were noted between risk of non-Hodgkin's lymphoma and acres sprayed in 1970 with herbicides, as well as with dollars spent on fuel and oil for farm purposes in 1970. Using Poisson regression modeling, we found that relative risks for the highest level of herbicide use (greater than or equal to 250 acres sprayed) and fuel purchased in 1970 (greater than or equal to $900) on farms less than 1,000 acres total area were 2.2 (95% confidence interval = 1.0-4.6) and 2.3 (95% confidence interval = 1.1-4.7), respectively.

Immunoisolation of GABA-specific synaptic vesicles defines a functionally distinct subset of synaptic vesicles.

Synaptic vesicles from mammalian brain are among the best characterized trafficking organelles. However, so far it has not been possible to characterize vesicle subpopulations that are specific for a given neurotransmitter. Taking advantage of the recent molecular characterization of vesicular neurotransmitter transporters, we have used an antibody specific for the vesicular GABA transporter (VGAT) to isolate GABA-specific synaptic vesicles. The isolated vesicles are of exceptional purity as judged by electron microscopy. Immunoblotting revealed that isolated vesicles contain most of the major synaptic vesicle proteins in addition to VGAT and are devoid of vesicular monoamine and acetylcholine transporters. The vesicles are 10-fold enriched in GABA uptake activity when compared with the starting vesicle fraction. Furthermore, glutamate uptake activity and glutamate-induced but not chloride-induced acidification are selectively lost during immunoisolation. We conclude that the population of GABA-containing synaptic vesicles is separable and distinct from vesicle populations transporting other neurotransmitters.

Synergistic effect of recombinant human leukemia inhibitory factor (LIF) and 1-beta-D-arabinofuranosylcytosine (Ara-C) on proto-oncogene expression and induction of differentiation in human U 937 cells.

The in vitro action of recombinant human leukemia inhibitory factor (LIF) and 1-beta-D arabinofuranosylcytosine (ara-C) was studied on the human leukemia cell line U 937. Parameters investigated included monitoring of transcript levels of the proto-oncogenes C-MYC, C-FOS, and C-FMS, and analysis of nitroblue tetrazolium (NBT) reduction and of surface expression of the C3 bi receptor. Furthermore clonal proliferation of U 937 cells was assessed in soft agar cultures. The results indicate that both agents have only little effects on U 937 cells when acting alone. When combined in culture, however, they synergize to induce monocytic differentiation of U 937 cells as disclosed by significant increase of cells capable of reducing NBT and displaying surface C3 bi receptor that was accompanied by reduction of clonogenicity in colony assays. Induction of differentiation and inhibition of proliferation of U 937 cells was preceded by downregulation of transcript levels of C-MYC, increase of C-FOS mRNA, and induction of accumulation of C-FMS mRNA. By sequential use of LIF and ara-C we also demonstrate that the basis of synergism of both agents does not involve mechanisms at the level of receptor ligation but that synergism may be initiated by complementary intracellular metabolic cascades.

Gamma-interferon interrupts growth stimulation in chronic myelogenous leukemia established by endogenous granulocyte colony-stimulating factor.

We have previously shown that maturing neoplastic cells from patients with stable phase chronic myelogenous leukemia (SP CML) constitutively produce granulocyte colony-stimulating factor (G-CSF) and are also receptive for this molecule. G-CSF functions as an endogenous growth factor in SP CML, and thus is responsible for divisions in maturing leukemic cells leading to an expansion of the compartment of mature cells. In the investigations to be reported below, the effects of various hematopoietic inhibitor molecules on the expression of the G-CSF gene by SP CML bone marrow cells enriched for promyelocytes/myelocytes were examined at the mRNA and protein level. We show that exposure of SP CML bone marrow promyelocytes/myelocytes to recombinant human (rh) interferon (IFN)-gamma but not to rh IFN-alpha, rh tumor necrosis factor (TNF)-alpha, and rh lymphotoxin (LT) leads to downregulation of G-CSF expression and interruption of the G-CSF-mediated endogenous growth stimulation. The action of G-CSF takes place at the posttranscriptional level and involves an acceleration of decay of steady-state levels of G-CSF transcripts in the malignant cell population.

Mechanisms of differential regulation of interleukin-6 mRNA accumulation by tumor necrosis factor alpha and lymphotoxin during monocytic differentiation.

In the present report we compare the capacity of two related cytokines, tumor necrosis factor (TNF) alpha and lymphotoxin (LT), to modulate mRNA levels of interleukin-6 (IL-6) in cells representing different stages of monocytic differentiation including the human leukemia cell lines HL 60, U 937, THP-1, MonoMac 1 and peripheral blood monocytes. We show that the capacity of TNF alpha and LT to induce IL-6 mRNA accumulation increases as monocytic differentiation proceeds with TNF alpha being more potent than LT, suggesting that alternate pathways may be used by differentiating cells to control expression of IL-6. In contrast, in monocytes which constitutively synthesize IL-6 transcripts, TNF alpha and LT treatment had opposite effects on levels of IL-6 mRNA accumulation. In these cells TNF alpha enhanced steady state levels of IL-6 transcripts due to mRNA stabilization, whereas LT shortened IL-6 mRNA half-life, most likely due to induction of a RNA destabilizer since LT-mediated downregulation of levels of IL-6 mRNA in monocytes could be prevented by inhibition of protein synthesis. Neither TNF alpha nor LT altered IL-6 mRNA accumulation by interfering with preexisting transcription factors since both TNF alpha and LT required de novo protein synthesis to exert their effects.

Differential tolerance induction by lipoarabinomannan and lipopolysaccharide in human macrophages.

Various bacterial cell wall components have been shown to induce hyporesponsiveness in macrophages (MAC). Here, mycobacterial glycolipids were employed to determine whether they induce a state of 'tolerance/hyporesponsiveness' in MAC in vitro in order to assess whether mycobacterial components negatively affect the immune response to Mycobacterium tuberculosis. Arabinosylated lipoarabinomannan (ARA-LAM) stimulated hyporesponsiveness by reducing TNF-alpha, GM-CSF, G-CSF, IL-10, and IL-6 release similarly to LPS, but caused no changes in IL-8 secretion. Mannose-capped LAM (MAN-LAM) acted in a different way in that TNF-alpha, GM-CSF, and IL-10 were upregulated after restimulation of MAC. Blocking experiments by mannan suggest mannose-receptor involvement in MAN-LAM activation only. Cross-stimulation experiments demonstrated a hierarchy of signaling, with LPS being the most potent stimulator and mediating abrogation of ARA-LAM-stimulated tolerance but not vice versa. MAN-LAM was the least potent stimulator of either MAC activation and induction of hyporesponsiveness. Similarly to LPS, ARA-LAM upregulated CD14 surface expression after restimulation. Recurrent MAN-LAM treatment either downmodulated or did not induce any change in CD14 expression. The role of MAN-LAM regulated cytokine secretion as well as implications regarding M. tuberculosis infection will be discussed.

A study of HTLV-I and its associated risk factors in Trinidad and Tobago.

Seroprevalence of human T-lymphotropic virus type 1 (HTLV-I) among a sample of persons selected from a government register of businesses in Trinidad was 3.2% in 1,025 persons of African descent compared to 0.2% among 487 persons of Asian descent and 0% among 46 persons of European-descent. In Tobago, from a coastal village, among persons of African ancestry ascertained as part of a cardiovascular survey, the rate was 11.4%, which was significantly higher when corrected for age and race than the rate in Trinidad. The seroprevalence rate of antibodies to hepatitis A and B was also significantly elevated in Tobago compared to Trinidad. HTLV-I seroprevalence rates were higher in females than males while hepatitis A and B rates were not significantly different in the two sexes. For males, age was a significant determinant of HTLV-I seropositivity, while for females, age, markers of poor sanitation, and hepatitis B were each independently linked to HTLV-I seropositivity. The frequent occurrence of multiple infectious exposures in persons of lower socioeconomic circumstances in this tropical environment may result in immune activation that heightens susceptibility to HTLV-I infection.

Transdermal nitroglycerin systems: methods for comparison.

A number of transdermal nitroglycerin delivery systems are able to maintain a constant plasma level of nitroglycerin for up to 24 hours, even though the drug's elimination half-life is only a few minutes. Unfortunately, wide variations in plasma drug levels reported in studies of transdermal delivery systems can make plasma level comparisons between products inappropriate and misleading. Other measures of clinical performance include adhesive properties and patient preference. In one adhesion study, Minitran demonstrated superior adhesive properties when compared with Transderm-Nitro, Nitro-Dur II, and a medical reference tape. In patient preference studies involving several hundred patients with angina pectoris, patients consistently selected Minitran over Transderm-Nitro or Nitro-Dur II, citing patch size, shape, ease of application, comfort, better patch adhesion, and reduced instances of skin irritation.

Drug release rates from four sizes of a new transdermal nitroglycerin adhesive patch.

This study was conducted to determine the amount of nitroglycerin released from transdermal nitroglycerin patches of four different sizes: 3.3 cm2, 6.7 cm2, 13.3 cm2, and 20 cm2. Thirty healthy men received a single 24-hour application of each patch size according to a randomized, open-label, four-period crossover design. A 24-hour interval separated each treatment period. The total amount of nitroglycerin released by the four patches was proportional to size. All four patch sizes released nitroglycerin at a comparable rate. The mean overall 24-hour release rate of 0.76 mg/cm2 was similar to the release rate of 0.75 mg/cm2/24 hr observed in a previous study. Adverse experiences common to nitroglycerin administration were reported for all patch sizes, with headache, light-headedness, and nausea reported most frequently.