Affimer-mediated locking of p21-activated kinase 5 in an intermediate activation state results in kinase inhibition

Kinases are important therapeutic targets, and their inhibitors are classified according to their mechanism of action, which range from blocking ATP binding to covalent inhibition. Here, a mechanism of inhibition is highlighted by capturing p21-activated kinase 5 (PAK5) in an intermediate state of activation using an Affimer reagent that binds in the P+1 pocket. PAK5 was identified from a non-hypothesis-driven high-content imaging RNAi screen in urothelial cancer cells. Silencing of PAK5 resulted in reduced cell number, G1/S arrest, and enlargement of cells, suggesting it to be important in urothelial cancer cell line survival and proliferation. Affimer reagents were isolated to identify mechanisms of inhibition. The Affimer PAK5-Af17 recapitulated the phenotype seen with siRNA. Co-crystallization revealed that PAK5-Af17 bound in the P+1 pocket of PAK5, locking the kinase into a partial activation state. This mechanism of inhibition indicates that another class of kinase inhibitors is possible.

Relevance of cleft palatal width in short-term otologic outcomes

OBJECTIVE

Children with cleft palate are at increased risk for Eustachian tube dysfunction (ETD) and conductive hearing loss from chronic otitis media. While it has been proposed that the severity of ETD is related to the severity of cleft palate, data are lacking to support this hypothesis. An improved understanding of the relevance of cleft width may have prognostic value that could inform decisions on the timing of tympanostomy tube placement and choice of tympanostomy tube design. The objective of this study was to assess severity of ETD in children with narrow, moderate, and wide cleft palate, with examination of hearing outcomes, number of tympanostomy procedures, and incidence of otologic complications.

METHODS

Retrospective chart review was conducted on 58 patients with primary palatoplasty performed at a single academic medical center from January 1, 2016-December 31, 2019. The primary outcome was the number of otologic procedures performed after the initial palatoplasty. Secondary outcomes included audiometric findings, number of tympanostomy tube placements, presence of effusion at the time of myringotomy, and occurrence of any postoperative otologic complication. Outcomes were compared for patients with narrow (<10 mm), moderate (10-15 mm), and wide (>15 mm) cleft palate. Analysis included consideration of cleft palatal morphology (Veau I - IV), presence of Robin sequence or syndromes, and risk factors for otitis media.

RESULTS

Patients with moderate and wide cleft palate underwent higher mean numbers of otologic procedures [narrow: 1.3 (95% confidence interval [CI] 0.9, 1.7); moderate: 1.6 (95% CI 1.1, 2.1); wide: 1.8 (95% CI 1.2, 2.4)]. Moderate and wide cleft palate were less likely to have normal hearing after their first tympanostomy (narrow: 50%, 10/20; moderate: 25%, 6/24; wide: 36%, 5/14). Patients with a wide cleft palate had a shorter median time between first and second tympanostomy procedures (median, IQR; narrow: 27.0, 20.8-35.7; moderate 20.4, 16.3-25.9; wide 17.3, 11.5-23.4).

CONCLUSION

Our findings suggest that patients with wider cleft palate may be more susceptible to severe ETD. Further large-scale study may help to allow for more informed and personalized clinical decision making for management of cleft palate, incorporating cleft width for prognosis of risks for persistent middle ear dysfunction.

Upregulated WEE1 protects endothelial cells of colorectal cancer liver metastases

Surgical resection of colorectal cancer liver metastases (CLM) can be curative, yet 80% of patients are unsuitable for this treatment. As angiogenesis is a determinant of CLM progression we isolated endothelial cells from CLM and sought a mechanism which is upregulated, essential for angiogenic properties of these cells and relevant to emerging therapeutic options. Matched CLM endothelial cells (CLMECs) and endothelial cells of normal adjacent liver (LiECs) were superficially similar but transcriptome sequencing revealed molecular differences, one of which was unexpected upregulation and functional significance of the checkpoint kinase WEE1. Western blotting confirmed that WEE1 protein was upregulated in CLMECs. Knockdown of WEE1 by targeted short interfering RNA or the WEE1 inhibitor AZD1775 suppressed proliferation and migration of CLMECs. Investigation of the underlying mechanism suggested induction of double-stranded DNA breaks due to nucleotide shortage which then led to caspase 3-dependent apoptosis. The implication for CLMEC tube formation was striking with AZD1775 inhibiting tube branch points by 83%. WEE1 inhibitors might therefore be a therapeutic option for CLM and could be considered more broadly as anti-angiogenic agents in cancer treatment.

Microsecond resolution of cavitation bubble dynamics using a high-speed electrochemical impedance approach

A new method to detect the uncompensated resistance, the capacitance and the Faradaic current at an electrode exposed to ultrasonic cavitation is presented. The method enables these parameters to be resolved with a 2 microsecond resolution and relies on the detection of the impedance of an electrode recorded as a function of time with a suitable AC excitation signal (here 500 kHz). Data obtained from an aluminium electrode, held under potentiostatic control, is used to illustrate the technique with particular relevance to the effects of cavitation bubbles generated by ultrasound. Analysis of the data recorded shows that the cavitation bubbles form close to the surface of the electrode and collapse, causing damage to the passive film formed at the aluminium surface. The capacitance, uncompensated resistance and Faradaic signals are used to explore the dynamic processes and show expansion and collapse of bubbles prior to erosion/corrosion. The close proximity of the bubbles to the surface is deduced from the reductions in capacitance and increases in resistance prior to bubble collapse, which is then shown to trigger the onset of a Faradaic signal, thus confirming the erosion/corrosion mechanism previously assumed.

In-vivo evidence that high mobility group box 1 exerts deleterious effects in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine model and Parkinson's disease which can be attenuated by glycyrrhizin

High-mobility group box 1 (HMGB1) is a nuclear and cytosolic protein that is released during tissue damage from immune and non-immune cells — including microglia and neurons. HMGB1 can contribute to progression of numerous chronic inflammatory and autoimmune diseases which is mediated in part by interaction with the receptor for advanced glycation endproducts (RAGE). There is increasing evidence from in vitro studies that HMGB1 may link the two main pathophysiological components of Parkinson's disease (PD), i.e. progressive dopaminergic degeneration and chronic neuroinflammation which underlie the mechanistic basis of PD progression.

Analysis of tissue and biofluid samples from PD patients, showed increased HMGB1 levels in human postmortem substantia nigra specimens as well as in the cerebrospinal fluid and serum of PD patients. In a mouse model of PD induced by sub-acute administration of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), systemic administration of neutralizing antibodies to HMGB1 partly inhibited the dopaminergic cell death, and reduced the increase of RAGE and tumour necrosis factor-alpha. The small natural molecule glycyrrhizin, a component from liquorice root which can directly bind to HMGB1, both suppressed MPTP-induced HMGB1 and RAGE upregulation while reducing MPTP-induced dopaminergic cell death in a dose dependent manner.

These results provide first in vivo evidence that HMGB1 serves as a powerful bridge between progressive dopaminergic neurodegeneration and chronic neuroinflammation in a model of PD, suggesting that HMGB1 is a suitable target for neuroprotective trials in PD.

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HMGB1 is up-regulated in Parkinson's disease.

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HMGB1 is translocalized into the cytoplasm after MPTP.

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Inhibition of HMGB1 protects against MPTP-toxicity.

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Translocalization of HMGB1 is reduced after inhibition a neutralizing antibody or glycyrrhizin.

The role of TWEAK/Fn14 signaling in the MPTP-model of Parkinson's disease

The tumor necrosis factor like weak inducer of apoptosis (TWEAK) and its receptor, fibroblast growth factor-inducible 14 (Fn14), mediate inflammation and neuronal apoptosis in cerebral edema, ischemic stroke and multiple sclerosis. The downstream effectors and pathways linked to TWEAK-Fn14 signaling are strongly implicated in the pathology of Parkinson's disease (PD), thus indicating a putative role for TWEAK/Fn14 signaling in PD neurodegeneration. Using the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model, we aimed to determine whether genetic ablation or pharmacologic mitigation of the TWEAK protein and its Fn14 receptor affected substantia nigra and striatum Parkinsonian pathology. Changes in endogenous TWEAK protein expression were also quantified in tissue from both MPTP-treated mice and PD human samples. TWEAK protein expression was transiently increased in the striatal tissue but remained unaltered in substantia nigra tissue of MPTP-treated mice. There was also no change of TWEAK protein levels in the substantia nigra or the striatum of human PD patients as compared to matched control subjects. Mitigating the effects of endogenous TWEAK protein using neutralizing antibody did affect MPTP-mediated neurotoxicity in the substantia nigra using the sub-acute model of MPTP (30mg/kg i.p. over five consecutive days). Neither TWEAK nor Fn14 genetic ablation led to attenuation of MPTP-toxicity in the acute model. These findings suggest that TWEAK signaling might be an aspect of MPTP-mediated neuropathology and be involved in the overall neurodegenerative pathology of PD.

Evidence for a role of adaptive immune response in the disease pathogenesis of the MPTP mouse model of Parkinson's disease

Parkinson's disease (PD) is the second most common neurodegenerative disease and results from the loss of dopaminergic neurons of the nigrostriatal pathway. The pathogenesis of PD is poorly understood, but inflammatory processes have been implicated. Indeed increases in the number of major histocompatibility complex II (MHC II) reactive cells have long been recognised in the brains of PD patients at post‐mortem. However whether cells expressing MHC II play an active role in PD pathogenesis has not been delineated. This was addressed utilising a transgenic mouse null for MHC II and the parkinsonian toxin 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine (MPTP). In wild‐type mice MHC II levels in the ventral midbrain were upregulated 1–2 days after MPTP treatment and MHC II was localized in both astrocytes and microglia. MHC II null mice showed significant reductions in MPTP‐induced dopaminergic neuron loss and a significantly reduced invasion of astrocytes and microglia in MHC II null mice receiving MPTP compared with controls. In addition, MHC II null mice failed to show increases in interferon‐γ or tumour necrosis factor‐α in the brain after MPTP treatment, as was found in wild‐type mice. However, interleukin‐1β was significantly increased in both wild‐type and MHC II null mice. These data indicate that in addition to microglial cell/myeloid cell activation MHC Class II‐mediated T cell activation is required for the full expression of pathology in this model of PD. GLIA 2016;64:386–395

MHCII upregulation is necessary for dopaminergic cell death in a model of Parkinson's disease. The study supports the presence of an adaptive immune response in the pathogenesis of Parkinson's disease.

Effect of parasitic infection on dopamine biosynthesis in dopaminergic cells

Infection by the neurotropic agent Toxoplasma gondii alters rodent behavior and can result in neuropsychiatric symptoms in humans. Little is understood regarding the effects of infection on host neural processes but alterations to dopaminergic neurotransmission are implicated. We have previously reported elevated levels of dopamine (DA) in infected dopaminergic cells however the involvement of the host enzymes and fate of the produced DA were not defined. In order to clarify the effects of infection on host DA biosynthetic enzymes and DA packaging we examined enzyme levels and activity and DA accumulation and release in T. gondii-infected neurosecretory cells. Although the levels of the host tyrosine hydroxylase (TH) and DOPA decarboxylase and AADC (DDC) did not change significantly in infected cultures, DDC was found within the parasitophorous vacuole (PV), the vacuolar compartment where the parasites reside, as well as in the host cytosol in infected dopaminergic cells. Strikingly, DDC was found within the intracellular parasite cysts in infected brain tissue. This finding could provide some explanation for observations of DA within tissue cysts in infected brain as a parasite-encoded enzyme with TH activity was also localized within tissue cysts. In contrast, cellular DA packaging appeared unchanged in single-cell microamperometry experiments and only a fraction of the increased DA was accessible to high potassium-induced release. This study provides some understanding of how this parasite produces elevated DA within dopaminergic cells without the toxic ramifications of free cytosolic DA. The mechanism for synthesis and packaging of DA by T. gondii-infected dopaminergic cells may have important implications for the effects of chronic T. gondii infection on humans and animals.

The effect of neuronal conditional knock-out of peroxisome proliferator-activated receptors in the MPTP mouse model of Parkinson's disease

Activation of peroxisome proliferator-activated receptors (PPARs), namely PPARγ and PPARδ, has been shown to provide neuroprotection in a number of neurodegenerative disorders, such as Alzheimer's and Parkinson's disease (PD). The observed neuroprotective effects in experimental models of PD have been linked to anti-oxidant and anti-inflammatory actions. This study aimed to analyze the full influence of these receptors in neuroprotection by generating a nerve cell-specific conditional knock-out of these receptors and subjecting these genetically modified mice to the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) neurotoxin to model dopaminergic degeneration. Mice null for both receptors show the lowest levels of tyrosine hydroxylase (TH)-positive cell bodies following MPTP administration. Presence of one or both these receptors show a trend toward protection against this degeneration, as higher dopaminergic cell immunoreactivity and striatal monoamine levels are evident. These data supplement recent studies that have elected to use agonists of the receptors to regulate immune responses. The results place further importance on the activation of PPARs and the neuroprotective roles these have in inflammatory processes linked to neurodegenerative processes.

Prognostic value of systemic inflammation-based markers in advanced pancreatic cancer

BACKGROUND

The prognostic significance of various systemic inflammation-based markers has been explored in different cancers. These markers can be used to assist with decision-making in oncology clinics.

AIM

The aim of this study was to investigate the prognostic significance of three systemic inflammation-based factors: neutrophil-lymphocyte ratio (NLR), platelet-lymphocyte ratio (PLR) and modified Glasgow Prognostic Score (mGPS) in patients with advanced pancreatic cancer.

METHODS

Data were collected retrospectively for advanced pancreatic cancer patients treated between 1 January 2008 and 31 December 2012 at the Royal Perth Hospital. The ratios were dichotomised as <5 versus ≥5 for NLR and <200 versus ≥200 for PLR. Modified Glasgow Prognostic Scores were scored as: mGPS '0' = both C-reactive protein (CRP) and albumin normal, mGPS '1' = elevated CRP < 10 mg/L and mGPS '2' = both elevated CRP > 10 mg/L and albumin < 35 g/L. Univariate and multivariate analyses were carried out.

RESULTS

Data were evaluable for 124 patients. Median survivals based on the three inflammation-based prognostic markers evaluated were: NLR <5 versus ≥5 = 8.5 months versus 2.6 months respectively (P = 0.0007; hazard ratio (HR) 1.81), PLR <200 versus ≥200 = 9.1 months versus 4 months respectively (P = 0.007; HR 1.64) and mGPS score 1, 2, 3 = 8.3 months, 9.6 months and 1.8 months respectively (P = 0.0004). Besides Eastern Cooperative Oncology Group performance status, NLR, PLR and mGPS were significant independent prognostic markers both on univariate as well as multivariate analysis.

CONCLUSIONS

Our findings suggest that the NLR, PLR and mGPS derived from routine blood tests can be used as clinically meaningful biomarkers to stratify advanced pancreatic cancer patients into different prognostic groups.

Selective and Potent Proteomimetic Inhibitors of Intracellular Protein-Protein Interactions

Inhibition of protein-protein interactions (PPIs) represents a major challenge in chemical biology and drug discovery. α-Helix mediated PPIs may be amenable to modulation using generic chemotypes, termed "proteomimetics", which can be assembled in a modular manner to reproduce the vectoral presentation of key side chains found on a helical motif from one partner within the PPI. In this work, it is demonstrated that by using a library of N-alkylated aromatic oligoamide helix mimetics, potent helix mimetics which reproduce their biophysical binding selectivity in a cellular context can be identified.

Selective and potent proteomimetic inhibitors of intracellular protein-protein interactions

Inhibition of protein–protein interactions (PPIs) represents a major challenge in chemical biology and drug discovery. α-Helix mediated PPIs may be amenable to modulation using generic chemotypes, termed “proteomimetics”, which can be assembled in a modular manner to reproduce the vectoral presentation of key side chains found on a helical motif from one partner within the PPI. In this work, it is demonstrated that by using a library of N-alkylated aromatic oligoamide helix mimetics, potent helix mimetics which reproduce their biophysical binding selectivity in a cellular context can be identified.

High-content, high-throughput screening for the identification of cytotoxic compounds based on cell morphology and cell proliferation markers

Toxicity is a major cause of failure in drug discovery and development, and whilst robust toxicological testing occurs, efficiency could be improved if compounds with cytotoxic characteristics were identified during primary compound screening. The use of high-content imaging in primary screening is becoming more widespread, and by utilising phenotypic approaches it should be possible to incorporate cytotoxicity counter-screens into primary screens. Here we present a novel phenotypic assay that can be used as a counter-screen to identify compounds with adverse cellular effects. This assay has been developed using U2OS cells, the PerkinElmer Operetta high-content/high-throughput imaging system and Columbus image analysis software. In Columbus, algorithms were devised to identify changes in nuclear morphology, cell shape and proliferation using DAPI, TOTO-3 and phosphohistone H3 staining, respectively. The algorithms were developed and tested on cells treated with doxorubicin, taxol and nocodazole. The assay was then used to screen a novel, chemical library, rich in natural product-like molecules of over 300 compounds, 13.6% of which were identified as having adverse cellular effects. This assay provides a relatively cheap and rapid approach for identifying compounds with adverse cellular effects during screening assays, potentially reducing compound rejection due to toxicity in subsequent in vitro and in vivo assays.

Multidrug-resistant breast cancer: current perspectives

Breast cancer is the most common cancer in women worldwide, and resistance to the current therapeutics, often concurrently, is an increasing clinical challenge. By understanding the molecular mechanisms behind multidrug-resistant breast cancer, new treatments may be developed. Here we review the recent advances in this understanding, emphasizing the common mechanisms underlying resistance to both targeted therapies, notably tamoxifen and trastuzumab, and traditional chemotherapies. We focus primarily on three molecular mechanisms, the phosphatidylinositide 3-kinase/Akt pathway, the role of microRNAs in gene silencing, and epigenetic alterations affecting gene expression, and discuss how these mechanisms can interact in multidrug resistance. The development of therapeutics targeting these mechanisms is also addressed.

A high-throughput assay to identify modifiers of premature chromosome condensation

Premature chromosome condensation (PCC) is a consequence of early mitotic entry, where mitosis begins before completion of DNA replication. Previously we have identified mutations in MCPH1, a DNA damage response and potential tumor suppressor gene, as a cause of primary microcephaly and PCC. Here we describe a high-throughput assay to identify modifiers of PCC. Reverse transfection of control siRNA followed by a forward transfection of MCPH1 small interfering RNA (siRNA) was performed to induce PCC. Condensin II subunits CAPG2 and CAPH2 were validated as PCC modifiers and therefore positive controls. Cell nuclei were detected by DAPI staining using an Operetta imaging system. PCC and nuclei number were determined using Columbus analysis software. Two batches of nine plates were used to determine assay efficacy. Each plate contained four negative (nontargeting) and eight positive control siRNAs. Mean % PCC was 12.35% (n = 72) for negative controls and 4.25% (n = 144) for positive controls. Overall false-positive and false-negative rates were 0% (n = 72) and 2.1% (n = 144), respectively. This assay is currently being used to screen a human druggable genome siRNA library to identify novel therapeutic targets for cancer treatment. The assay can also be used to identify novel compounds and genes that induce PCC.

S100B is increased in Parkinson's disease and ablation protects against MPTP-induced toxicity through the RAGE and TNF-α pathway

Parkinson’s disease is a neurodegenerative disorder that can, at least partly, be mimicked by the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine. S100B is a calcium-binding protein expressed in, and secreted by, astrocytes. There is increasing evidence that S100B acts as a cytokine or damage-associated molecular pattern protein not only in inflammatory but also in neurodegenerative diseases. In this study, we show that S100B protein levels were higher in post-mortem substantia nigra of patients with Parkinson’s disease compared with control tissue, and cerebrospinal fluid S100B levels were higher in a large cohort of patients with Parkinson’s disease compared with controls. Correspondingly, mice treated with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine showed upregulated S100B messenger RNA and protein levels. In turn, ablation of S100B resulted in neuroprotection, reduced microgliosis and reduced expression of both the receptor for advanced glycation endproducts and tumour necrosis factor-α. Our results demonstrate a role of S100B in the pathophysiology of Parkinson’s disease. Targeting S100B may emerge as a potential treatment strategy in this disorder.

Toxoplasma gondii infection and behaviour - location, location, location?

Parasite location has been proposed as an important factor in the behavioural changes observed in rodents infected with the protozoan Toxoplasma gondii. During the chronic stages of infection, encysted parasites are found in the brain but it remains unclear whether the parasite has tropism for specific brain regions. Parasite tissue cysts are found in all brain areas with some, but not all, prior studies reporting higher numbers located in the amygdala and frontal cortex. A stochastic process of parasite location does not, however, seem to explain the distinct and often subtle changes observed in rodent behaviour. One factor that could contribute to the specific changes is increased dopamine production by T. gondii. Recently, it was found that cells encysted with parasites in the brains of experimentally infected rodents have high levels of dopamine and that the parasite encodes a tyrosine hydroxylase, the rate-limiting enzyme in the synthesis of this neurotransmitter. A mechanism is proposed that could explain the behaviour changes due to parasite regulation of dopamine. This could have important implications for T. gondii infections in humans.

Pharmacological manipulation of peroxisome proliferator-activated receptor γ (PPARγ) reveals a role for anti-oxidant protection in a model of Parkinson's disease

Peroxisome proliferator-activated receptor γ (PPARγ) agonists have been shown to provide neuroprotection in a number of neurodegenerative diseases including Parkinson's disease and Alzheimer's disease. These protective effects are primarily considered to result from the anti-inflammatory actions of PPARγ, however, there is increasing evidence that anti-oxidant mechanisms may also contribute. This study explored the impact of the PPARγ agonist rosiglitazone and the PPARγ antagonist GW9662 in the MPP(+)/MPTP (1-methyl-4-phenylpyridinium/1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) model of Parkinson's disease, focussing on oxidative stress mechanisms. Rosiglitazone attenuated reactive oxygen species formation induced by MPP(+) in SH-SY5Y cells concurrent with an upregulation of glutathione-S-transferase activity, but not superoxide dismutase activity. These responses were not attenuated by cotreatment with GW9662 suggesting that PPARγ activation is not required. The localisation of PPARγ in vivo to dopaminergic neurons of the substantia nigra pars compacta (SNpc) was established by immunohistochemistry and PPARγ levels were found to be upregulated 7 days after MPTP treatment. The importance of PPARγ in protecting against MPTP toxicity was confirmed by treating C57BL6 mice with GW9662. Treatment with GW9662 increased MPTP-induced neuronal loss in the SNpc whilst not affecting MPTP-induced reductions in striatal dopamine and 3,4-dihdroxyphenylacetic acid. GW9662 also caused neuronal loss in the SNpc of saline-treated mice. The evidence presented here supports the role of anti-oxidant mechanisms in the protective effects of PPARγ agonists in neurodegenerative diseases, but indicates that these effects may be independent of PPARγ activation. It also demonstrates the importance of PPARγ activity for neuronal survival within the SNpc.

Receptor for advanced glycation endproducts (RAGE) deficiency protects against MPTP toxicity

Parkinson's disease (PD) is a common neurodegenerative disorder of unknown pathogenesis characterized by the loss of nigrostriatal dopaminergic neurons. Oxidative stress, microglial activation and inflammatory responses seem to contribute to the pathogenesis. The receptor for advanced glycation endproducts (RAGE) is a multiligand receptor of the immunoglobulin superfamily of cell surface molecules. The formation of advanced glycation end products (AGEs), the first ligand of RAGE identified, requires a complex series of reactions including nonenzymatic glycation and free radical reactions involving superoxide-radicals and hydrogen peroxide. Binding of RAGE ligands results in activation of nuclear factor-kappaB (NF-κB). We show that RAGE ablation protected nigral dopaminergic neurons against cell death induced by the neurotoxin MPTP that mimics most features of PD. In RAGE-deficient mice the translocation of the NF-κB subunit p65 to the nucleus, in dopaminergic neurons and glial cells was inhibited suggesting that RAGE involves the activation of NF-κB. The mRNA level of S100, one of the ligands of RAGE, was increased after MPTP treatment. The dopaminergic neurons treated with MPP(+) and S100 protein showed increased levels of apoptotic cell death, which was attenuated in RAGE-deficient mice. Our results suggest that activation of RAGE contributes to MPTP/MPP(+)-induced death of dopaminergic neurons that may be mediated by NF-κB activation.

Glutathione--a review on its role and significance in Parkinson's disease

Parkinson's disease (PD) is the second most common neurodegenerative disease, affecting over a million people in the United States alone, and is characterized by rigidity, bradykinesia, resting tremor, and postural instability. Its main neuropathological feature is the loss of dopaminergic neurons of the substantia nigra pars compacta. However, the pathogenesis of this loss is not understood fully. One of the earliest biochemical changes seen in PD is a reduction in the levels of total glutathione, a key cellular antioxidant. Traditionally, it has been thought that this decrease in GSH levels is the consequence of increased oxidative stress, a process heavily implicated in PD pathogenesis. However, emerging evidence suggests that GSH depletion may itself play an active role in PD pathogenesis. This review aims to explore the contribution of GSH depletion to PD pathogenesis.

Measurement and modeling of the toxicity of binary mixtures in the nematode caenorhabditis elegans--a test of independent action

Ecological risk assessments must increasingly consider the effects of chemical mixtures on the environment as anthropogenic pollution continues to grow in complexity. Yet testing every possible mixture combination is impractical and unfeasible; thus, there is an urgent need for models that can accurately predict mixture toxicity from single-compound data. Currently, two models are frequently used to predict mixture toxicity from single-compound data: Concentration addition and independent action (IA). The accuracy of the predictions generated by these models is currently debated and needs to be resolved before their use in risk assessments can be fully justified. The present study addresses this issue by determining whether the IA model adequately described the toxicity of binary mixtures of five pesticides and other environmental contaminants (cadmium, chlorpyrifos, diuron, nickel, and prochloraz) each with dissimilar modes of action on the reproduction of the nematode Caenorhabditis elegans. In three out of 10 cases, the IA model failed to describe mixture toxicity adequately with significant or antagonism being observed. In a further three cases, there was an indication of synergy, antagonism, and effect-level-dependent deviations, respectively, but these were not statistically significant. The extent of the significant deviations that were found varied, but all were such that the predicted percentage effect seen on reproductive output would have been wrong by 18 to 35% (i.e., the effect concentration expected to cause a 50% effect led to an 85% effect). The presence of such a high number and variety of deviations has important implications for the use of existing mixture toxicity models for risk assessments, especially where all or part of the deviation is synergistic.

Cerebral palsy: what do medical students know and believe?

OBJECTIVES

Negative attitudes toward people with disabilities, including cerebral palsy, may be related to misunderstandings or lack of knowledge about the disability. If held by medical practitioners, they can have detrimental implications for the care of people with disabilities. The purposes of this study were to examine the knowledge and attitudes of medical students regarding cerebral palsy and to examine the effects of the videotape 'Understanding Cerebral Palsy' on these two areas.

METHODS

The attitudes and knowledge regarding cerebral palsy of 54 medical students in their penultimate year were measured before and after watching a video produced to educate health professionals about cerebral palsy. They were assessed using a self-administered questionnaire constructed specifically for the study, adapted from previously validated questionnaires.

RESULTS

These medical students generally had limited knowledge about cerebral palsy and displayed negative attitudes toward people with cerebral palsy. It was also found that males had less positive attitudes than females (P = 0.014) and that students educated mainly in Asia had less positive attitudes than students educated mainly in Australia (P = 0.012). The videotape was shown to be effective in improving the students' knowledge about cerebral palsy. A small but significant improvement in attitudes was also shown (P = 0.014), with the attitudes of some students improving dramatically. However, negative attitudes remained in many.

CONCLUSIONS

Based on the findings, structured teaching about cerebral palsy is necessary within the medical curriculum at the University of Melbourne. Greater promotion of positive attitudes toward people with cerebral palsy and other disabilities is required.

First Report of Acidovorax avenae subsp. citrulli as a Pathogen of Gramma in Australia

In March 2001, a foliar bacterial disease was observed on gramma seedlings (Cucurbita moschata L.) cv. Ken Special Hybrid 864 in a commercial nursery in Bowen, north Queensland, Australia. Symptoms included chlorosis of cotyledons and angular, water-soaked lesions from the tips of the cotyledons to the petioles. Brown, angular, water-soaked lesions that were delimited by the leaf veins were also present on newly emerged true leaves. Streaming of bacterial cells from the edges of cut lesions was seen in a droplet of water with ×100 magnification. Isolations attempted on King's medium B consistently yielded a slow-growing, cream to white, gram-negative bacterium. Bacterium was identified as Acidovorax avenae subsp. citrulli based on carbon source utilization profiles (Biolog, Hayward CA) and polymerase chain reaction (PCR) using a primer pair based on the 16S-23S internal transcribed spacer region. When tested in rep-PCR with the BoxA1R primer (2), the isolate produced a banding pattern similar to other Australian A. avenae subsp. citrulli isolates previously shown to be pathogenic to rockmelon (1). Koch's postulates were completed with 20 2-week-old glasshouse-grown gramma (cv. Ken Special Hybrid 864) seedlings. Seedlings were misted until runoff with a 3 × 10⁸ CFU/ml bacterial suspension and enclosed in plastic bags for 48 h at 23°C. Water-soaked lesions developed on cotyledons of all seedlings 6 days after inoculation, and bacterium was reisolated from symptomatic tissue. To our knowledge, this is the first report of A. avenae subsp. citrulli as a pathogen of C. moschata References: (1) R. G. O'Brien and H. L. Martin. Aust. J. Exp. Agric. 39:479, 1999 (2) J. Versalovic et al. Methods Mol. Cell Biol. 5:25, 1994.

Hormonal contraception and risk of sexually transmitted disease acquisition: results from a prospective study

OBJECTIVES

To examine the relationship between use of oral contraceptive pills or depot medroxyprogesterone acetate and sexually transmitted disease acquisition.

STUDY DESIGN

Prospective cohort included 948 Kenyan prostitutes. Multivariate Andersen-Gill proportional hazards models were constructed, adjusting for sexual behavioral and demographic variables.

RESULTS

When compared with women who were using no contraception, users of oral contraceptive pills were at increased risk for acquisition of chlamydia (hazard ratio, 1.8; 95% confidence interval, 1.1-2.9) and vaginal candidiasis (hazard ratio, 1.5; 95% confidence interval, 1.2-1.9) and at decreased risk for bacterial vaginosis (hazard ratio, 0.8; 95% confidence interval, 0.7-1.0). Women using depot medroxyprogesterone acetate had significantly increased risk of chlamydia infection (hazard ratio, 1.6; 95% confidence interval, 1.1-2.4) and significantly decreased risk of bacterial vaginosis (hazard ratio, 0.7; 95% confidence interval, 0.5-0.8), trichomoniasis (hazard ratio, 0.6; 95% confidence interval, 0.4-1.0), and pelvic inflammatory disease (hazard ratio, 0.4; 95% confidence interval, 0.2-0.7). Consistent condom use was associated with significantly decreased risk of gonorrhea, chlamydia, genital ulcer disease, bacterial vaginosis, and pelvic inflammatory disease.

CONCLUSIONS

The use of oral or injectable hormonal contraception altered susceptibility to sexually transmitted diseases, which may in turn influence transmission of human immunodeficiency virus type 1. Consistent condom use was protective with regards to sexually transmitted disease and should be encouraged for the prevention of sexually transmitted disease and human immunodeficiency virus type 1 among women who use hormonal contraception.

Validation of a modified commercial enzyme-linked immunoassay for detection of human immunodeficiency virus type 1 immunoglobulin G antibodies in saliva

This study was performed to evaluate the performance of a saliva collection device (OmniSal) and an enzyme-linked immunoassay (EIA) designed for use on serum samples (Detect HIV1/2) to detect human immunodeficiency virus type 1 (HIV-1) antibodies in the saliva of high-risk women in Mombasa, Kenya. The results of the saliva assay were compared to a "gold standard" of a double-EIA testing algorithm performed on serum. Individuals were considered HIV-1 seropositive if their serum tested positive for antibodies to HIV-1 by two different EIAs. The commercial serum-based EIA was modified to test the saliva samples by altering the dilution and lowering the cutoff point of the assay. Using the saliva sample, the EIA correctly identified 102 of the 103 seropositive individuals, yielding a sensitivity of 99% (95% confidence interval [CI], 94 to 100%), and 96 of the 96 seronegative individuals, yielding a specificity of 100% (95% CI, 95 to 100%). In this high-risk population, the positive predictive value of the assay was 100% and the negative predictive value was 99%. We conclude that HIV-1 antibody testing of saliva samples collected with this device and tested by this EIA is of sufficient sensitivity and specificity to make this protocol useful in epidemiological studies.

Trends in HIV-1 incidence in a cohort of prostitutes in Kenya: implications for HIV-1 vaccine efficacy trials

BACKGROUND

Accurate predictions of HIV-1 incidence in potential study populations are essential for designing HIV-1 vaccine efficacy trials. Little information is available on the estimated incidence of HIV-1 in such populations, especially information on incidence over time and incidence while participating in risk-reduction programs.

OBJECTIVES

To examine time trends in HIV-1 incidence in a vaccine preparedness cohort.

DESIGN

Prospective cohort study of female prostitutes in Mombasa, Kenya.

METHODS

HIV-1 incidence was determined using open and closed cohort designs. Generalized estimating equations were used to model HIV-1 and sexually transmitted disease (STD) incidence and sexual risk behaviors over time.

RESULTS

When analyzed as a closed cohort, HIV-1 incidence declined 10-fold during 3 years of follow-up (from 17.4 to 1.7 cases/100 person-years; p <.001). More than 50% of the cases of HIV-1 occurred during the first 6 months after enrollment, and 73% during the first 12 months. When analyzed as an open cohort, HIV-1 incidence density fell during the first 4 calendar years, influenced by accumulation of lower risk participants and variations in study recruitment. Significant declines occurred in both STD incidence and high-risk sexual behaviors during follow-up.

CONCLUSIONS

This study documents a dramatic decline in the risk of HIV-1 infection while participating in a prospective cohort, with most seroconversions occurring within 1 year of enrollment. Variations in HIV-1 incidence within high-risk populations should be anticipated during the design of vaccine trials.

Primary human immunodeficiency virus type 1 infection: clinical manifestations among women in Mombasa, Kenya

The occurrence of clinical manifestations associated with primary human immunodeficiency virus type 1 (HIV-1) infection was evaluated in a prospective cohort study of female sex workers in Mombasa, Kenya. Among 103 women who seroconverted to HIV-1, fever, vomiting, diarrhea, headache, arthralgia, myalgia, skin rash, swollen lymph nodes, extrainguinal lymphadenopathy, inguinal lymphadenopathy, and vaginal candidiasis were noted significantly more frequently at visits in which seroconversion first became evident. Eighty-one percent of seroconverting women had >/=1 of these 11 symptoms or signs. Among 44% of the women, the acute illness was severe enough to prevent them from working. Having >/=2 of 6 selected symptoms and signs yielded a sensitivity of 51%, specificity of 83%, positive likelihood ratio of 3.2, and negative likelihood ratio of 0.5 for acute HIV-1 infection. The recognition of primary HIV-1-infection illness in high-risk populations and subsequent risk-reduction counseling could potentially reduce secondary HIV-1 transmission during this highly infectious period.

Gender differences in HIV-1 diversity at time of infection

To develop an HIV-1 vaccine with global efficacy, it is important to identify and characterize the viruses that are transmitted, particularly to individuals living in areas of high incidence. Several studies have shown that virus from the blood of acutely infected adults was homogeneous, even when the virus population in the index case was genetically diverse. In contrast to those results with mainly male cohorts in America and Europe, in several cases a heterogeneous virus population has been found early in infection in women in Africa. Thus, we more closely compared the diversity of transmitted HIV-1 in men and women who became infected through heterosexual contact. We found that women from Kenya were often infected by multiple virus variants, whereas men from Kenya were not. Moreover, a heterogeneous virus was present in the women before their seroconversion, and in each woman it was derived from a single index case, indicating that diversity was most likely to be the result of transmission of multiple variants. Our data indicate that there are important differences in the transmitted virus populations in women and men, even when cohorts from the same geographic region who are infected with the same subtypes of HIV-1 are compared.

Vaginal lactobacilli, microbial flora, and risk of human immunodeficiency virus type 1 and sexually transmitted disease acquisition

A prospective cohort study was conducted to examine the relationship between vaginal colonization with lactobacilli, bacterial vaginosis (BV), and acquisition of human immunodeficiency virus type 1 (HIV-1) and sexually transmitted diseases in a population of sex workers in Mombasa, Kenya. In total, 657 HIV-1-seronegative women were enrolled and followed at monthly intervals. At baseline, only 26% of women were colonized with Lactobacillus species. During follow-up, absence of vaginal lactobacilli on culture was associated with an increased risk of acquiring HIV-1 infection (hazard ratio [HR], 2.0; 95% confidence interval [CI], 1.2-3.5) and gonorrhea (HR, 1.7; 95% CI, 1.1-2.6), after controlling for other identified risk factors in separate multivariate models. Presence of abnormal vaginal flora on Gram's stain was associated with increased risk of both HIV-1 acquisition (HR, 1.9; 95% CI, 1.1-3.1) and Trichomonas infection (HR, 1.8; 95% CI, 1.3-2.4). Treatment of BV and promotion of vaginal colonization with lactobacilli should be evaluated as potential interventions to reduce a woman's risk of acquiring HIV-1, gonorrhea, and trichomoniasis.

First Report of Acidovorax avenae subsp. citrulli as a Pathogen of Cucumber

In March 1999, a foliar bacterial disease was observed in a commercial crop of cucumber (Cucumis sativus L.) cv. Jetset in Gumlu in northern Queensland, Australia. Initial symptoms consisted of angular, chlorotic, water-soaked lesions that later dried to necrotic areas of light brown, dead tissue. White bacterial ooze was commonly found on the undersides of young water-soaked lesions. Lesions were delimited by veins and distributed uniformly over leaf surfaces, and more than 20% of the crop was affected. No symptoms were observed on plant stems or fruits. Bacterial streaming from the edges of freshly cut young lesions was clearly visible in a droplet of water under ×100 magnification in the laboratory. Isolations were made from young lesions on King's medium B (1). A slow-growing, white, gram-negative, nonfluorescent bacterium was consistently isolated. Three isolates of the bacterium were identified, using the Biolog software program (Biolog, Hayward CA), and in each instance, the bacterium was confirmed as Acidovorax avenae subsp. citrulli, with a similarity of >0.80. Koch's postulates were completed with 8-day-old glasshouse-grown cucumber (cv. Jetset) seedlings. Seedlings were misted until runoff with a bacterial suspension of 3 × 10⁸ CFU/ml and enclosed in plastic bags for ≈30 h at 22°C. Water-soaked lesions were observed on cucumber cotyledons 4 days after inoculation. This is the first report of A. avenae subsp. citrulli as a pathogen of cucumber. Reference: (1) E. O. King et al. J. Lab. Clin. Med. 44:301, 1954.

Evolution of envelope sequences from the genital tract and peripheral blood of women infected with clade A human immunodeficiency virus type 1

The development of viral diversity during the course of human immunodeficiency virus type 1 (HIV-1) infection may significantly influence viral pathogenesis. The paradigm for HIV-1 evolution is based primarily on studies of male cohorts in which individuals were presumably infected with a single virus variant of subtype B HIV-1. In this study, we evaluated virus evolution based on sequence information of the V1, V2, and V3 portions of HIV-1 clade A envelope genes obtained from peripheral blood and cervical secretions of three women with genetically heterogeneous viral populations near seroconversion. At the first sample following seroconversion, the number of nonsynonymous substitutions per potential nonsynonymous site (dn) significantly exceeded substitutions at potential synonymous sites (ds) in plasma viral sequences from all individuals. Generally, values of dn remained higher than values of ds as sequences from blood or mucosa evolved. Mutations affected each of the three variable regions of the envelope gene differently; insertions and deletions dominated changes in V1, substitutions involving charged amino acids occurred in V2, and sequential replacement of amino acids over time at a small subset of positions distinguished V3. The relationship among envelope nucleotide sequences obtained from peripheral blood mononuclear cells, plasma, and cervical secretions was evaluated for each individual by both phylogenetic and phenetic analyses. In all subjects, sequences from within each tissue compartment were more closely related to each other than to sequences from other tissues (phylogenetic tissue compartmentalization). At time points after seroconversion in two individuals, there was also greater genetic identity among sequences from the same tissue compartment than among sequences from different tissue compartments (phenetic tissue compartmentalization). Over time, temporal phylogenetic and phenetic structure was detectable in mucosal and plasma viral samples from all three women, suggesting a continual process of migration of one or a few infected cells into each compartment followed by localized expansion and evolution of that population.

Hormonal contraception, sexually transmitted diseases, and risk of heterosexual transmission of human immunodeficiency virus type 1

To examine associations between method of contraception, sexually transmitted diseases (STDs), and incident human immunodeficiency virus type 1 (HIV-1) infection, a prospective observational cohort study was done among female sex workers attending a municipal STD clinic in Mombasa, Kenya. Demographic and behavioral factors significantly associated with HIV-1 infection included type of workplace, condom use, and parity. In multivariate models, vulvitis, genital ulcer disease, vaginal discharge, and Candida vaginitis were significantly associated with HIV-1 seroconversion. Women who used depo medroxyprogesterone acetate (DMPA) had an increased incidence of HIV-1 infection (hazard ratio [HR], 2.2; 95% confidence interval [CI], 1.4-3.4). In a multivariate model controlling for demographic and exposure variables and biologic covariates, the adjusted HR for HIV-1 infection among DMPA users was 2.0 (CI, 1.3-3.1). There was a trend for an association between use of high-dose oral contraceptive pills and HIV-1 acquisition (HR, 2.6; CI, 0.8-8.5).

Use of nonoxynol-9 and changes in vaginal lactobacilli

Several in vitro studies have shown nonoxynol-9 (N-9) to be toxic to lactobacilli, especially to strains that produce H2O2. Data from a randomized, double-blind, placebo-controlled crossover trial that investigated the safety and toxicity of 2 weeks of daily vaginal application of an N-9 gel were analyzed, to examine the effect of N-9 use on vaginal lactobacilli and bacterial vaginosis. In vivo, N-9 promoted sustained colonization by H2O2-producing lactobacilli among women already colonized (relative risk [RR], 1.8; 95% confidence interval [CI], 1.2-2.7). In addition, use of N-9 for 2 weeks reduced the likelihood of bacterial vaginosis (RR, 0.5; 95% CI, 0.3-1.0). In contrast, N-9 use by women initially colonized only by non-H2O2-producing lactobacilli resulted in loss of vaginal lactobacilli (RR, 2.5; 95% CI, 1.2-5.3). These data suggest that daily use of N-9 does not adversely affect vaginal colonization by H2O2-producing lactobacilli but that such use may promote loss of non-H2O2-producing strains.

Hormonal contraception, vitamin A deficiency, and other risk factors for shedding of HIV-1 infected cells from the cervix and vagina

BACKGROUND

Factors that influence shedding of HIV-1 infected cells in cervical and vaginal secretions may be important determinants of sexual and vertical transmission of the virus. We investigated whether hormonal contraceptive use, vitamin A deficiency, and other variables were risk factors for cervical and vaginal shedding of HIV-infected cells.

METHODS

Between December, 1994, and April, 1996, women who attended a municipal sexually transmitted diseases (STDs) clinic in Mombasa, Kenya, and had previously tested positive for HIV-1, were invited to take part in our cross-sectional study. Cervical and vaginal secretions from 318 women were evaluated for the presence of HIV-1 infected cells by PCR amplification of gag DNA sequences.

FINDINGS

HIV-1 infected cells were detected in 51% of endocervical and 14% of vaginal-swab specimens. Both cervical and vaginal shedding of HIV-1 infected cells were highly associated with CD4 lymphocyte depletion (p = 0.00001 and p = 0.003, respectively). After adjustment for CD4 count, cervical proviral shedding was significantly associated with use of depot medroxyprogesterone acetate (odds ratio 2.9, 95% CI 1.5-5.7), and with use of low-dose and high-dose oral contraceptive pills (3.8, 1.4-9.9 and 12.3, 1.5-101, respectively). Vitamin A deficiency was highly predictive of vaginal HIV-1 DNA shedding. After adjustment for CD4 count, severe vitamin A deficiency, moderate deficiency, and low normal vitamin A status were associated with 12.9, 8.0, and 4.9-fold increased odds of vaginal shedding, respectively. Gonococcal cervicitis (3.1, 1.1-9.8) and vaginal candidiasis (2.6, 1.2-5.4) were also correlated with significant increases in HIV-1 DNA detection, but Chlamydia trachomatis and Trichomonas vaginalis were not.

INTERPRETATION

Our study documents several novel correlates of HIV-1 shedding in cervical and vaginal secretions, most notably hormonal contraceptive use and vitamin A deficiency. These factors may be important determinants of sexual or vertical transmission of HIV-1 and are of public health importance because they are easily modified by simple interventions.

Decreased incidence of sexually transmitted diseases among trucking company workers in Kenya: results of a behavioural risk-reduction programme

OBJECTIVE

To establish a cohort of high-risk individuals suitable for HIV-prevention trials, and to measure changes in sexual behaviour and sexually transmitted disease (STD) incidence after a behavioural intervention.

DESIGN

Prospective cohort study in trucking company depots in Mombasa, Kenya.

PARTICIPANTS

A total of 556 male HIV-seronegative employees of trucking companies.

INTERVENTIONS

HIV serological testing, individual counselling, condom promotion, STD diagnosis and management.

MAIN OUTCOME MEASURES

Sexual risk behaviour and symptomatic STD incidence.

RESULTS

Using time-trend modelling, significant declines in self-reported high-risk sexual behaviour were demonstrated during a 1-year follow-up. The percentage of men reporting any extramarital sex during the 3-month period prior to a follow-up visit decreased from 49% durig the first quarter of follow-up to 36% during the last quarter (P < 0.001). The decline in reported female sex worker contact was from 12% to 6% (P = 0.001). Approximately 30% of men reported consistent condom use during extramarital sex and this percentage remained unchanged during the study period. The incidence of STD declined from 34 per 100 person years (PY) during the first quarter to 10 per 100 PY during the last quarter (P = 0.001). Significant reductions in gonorrhoea (15 to five cases per 100 PY, P = 0.04), non-gonococcal urethritis (10 to two cases per 100 PY, P = 0.05), and genital ulcer disease (nine to two cases per 100 PY, P = 0.02) were observed.

CONCLUSIONS

Among truck company workers who participated in a cohort study in Mombasa, Kenya, there was a significant decrease in sex with high-risk partners, but no change in condom use. The change in heterosexual risk behaviour was accompanied by a significant decrease in incidence of gonorrhoea, non-gonococcal urethritis, and genital ulcer disease.

Safety of a nonoxynol-9 vaginal gel in Kenyan prostitutes. A randomized clinical trial

OBJECTIVE

To evaluate the safety and toxicity of once-daily administration of Advantage-24 (Columbia Research Laboratories, Inc., Rockville Centre, NY), a vaginal gel containing 52.5 mg of nonoxynol-9 (N-9), including the effects of this gel on the vaginal and cervical epithelium.

STUDY DESIGN

Randomized, placebo-controlled, double-blind crossover trial, with a 2-week product application period and a 2-week washout period.

METHODS

Female sex workers in Mombasa, Kenya were randomized to one of two sequences, N-9 followed by placebo, or vice versa. Women were instructed to apply one applicator of N-9 or placebo gel vaginally once each day. During each of the two product periods, subjects were evaluated by questionnaire and physical examination, including colposcopy, after 7 and 14 days of product use. The primary outcome was genital epithelial disruption.

RESULTS

Sixty subjects were randomized, of whom 52 (87%) had complete follow-up. There were four episodes of epithelial disruption, three of which occurred during the placebo period and one during the N-9 period. The estimated risk of epithelial disruption associated with N-9 use was 0.33 (95% confidence interval, 0.03-3.26). There was no increased frequency of other, nondisruptive epithelial lesions during N-9 use.

CONCLUSIONS

No genital epithelial toxicity of N-9 vaginal gel was observed. This safety profile suggests that this N-9 product is appropriate for evaluation for human immunodeficiency virus type 1 prevention in a phase III efficacy trial.

Diversity in virus populations from genital secretions and peripheral blood from women recently infected with human immunodeficiency virus type 1

In order to develop a human immunodeficiency virus type 1 vaccine with global efficacy, it is important to evaluate the virus populations that are transmitted to individuals living in high-incidence areas. To determine the nature of the human immunodeficiency virus type 1 population transmitted to women during heterosexual contact, we examined the diversity of the proviral envelope gene in infected cells in both genital secretions and peripheral blood from six recently seroconverted Kenyan women. Heterogeneous virus populations were present in cervical secretions and/or peripheral blood shortly after seroconversion for five of six infected individuals, and tissue-specific variants were identified in several cases.

Acceptability of HIV vaccine trials in high-risk heterosexual cohorts in Mombasa, Kenya

OBJECTIVES

To ascertain the level of acceptance of a prophylactic HIV vaccine trial in high-risk HIV-seronegative heterosexual cohorts of men and women in Mombasa, Kenya, and to assess the anticipated effects of participation on risk behavior.

METHODS

Standardized questionnaire administered to a convenience sample of commercial sex workers and trucking company employees enrolled in prospective cohort studies.

RESULTS

Ninety-six per cent of respondents believed that HIV was a major problem in Kenya and 86% of men and 94% of women perceived themselves at risk. One hundred per cent of women and 84% of men expressed interest in participation in an HIV vaccine trial, after explanation of the experimental nature of the vaccine, double-blind placebo-controlled design, prolonged follow-up and potential change in serostatus. Seventeen per cent of men and 9% of women anticipated an increase in risk behavior as a result of participation.

CONCLUSION

The majority of individuals in two high-risk cohorts were interested in participating in Phase III efficacy trials of HIV vaccines. A significant minority anticipated an increase in risk behavior, which emphasizes the need for intensive counseling and education throughout a vaccine trial.

Maximal skin vascular conductance in subjects aged 5-85 yr

This study examined maximal forearm skin vascular conductance (FVCmax) as a function of age in 74 healthy male and female subjects ranging in age from 5 to 85 yr. The skin temperature of the left forearm was uniformly clamped at 42 degrees C by spraying a fine mist of water over the surface. Forearm blood flow (FBF) was measured by venous occlusion plethysmography (Hg-in-Silastic strain gauge). After 60 min of heating, a reactive hyperemia maneuver was performed to verify that forearm skin blood flow was maximal by using laser Doppler flowmetry to isolate the skin component of FBF. The maximal FBF of each subject was then divided by mean arterial pressure to yield FVCmax (in ml.100 ml-1.min-1.100 mmHg-1), i.e., minimal resistance. The model that best fits the data was curvilinear, as described by FVCmax = 13.1 + 86.9 (age-0.75) (r2 = 0.52, P < 0.001). The exclusion of subjects younger than 18 yr of age simplified the model to a linear fit with a slope of -0.16 conductance units/yr for adults. Interindividual variability remained constant across the entire age span. Once the age effect was considered, there were no significant effects of gender, adiposity, resting blood pressure, physical activity level, or body surface area on FVCmax.

Vitamin E in foods from high and low linoleic acid diets

As part of a human diet study, vitamin E activity was estimated in foods used in seven daily menus. Each menu was designed to contain 35% fat calories with either 10 or 30 gm/day of linoleic acid (18:2) and 500 mg/day of cholesterol. To estimate vitamin E activity, each food used in the menus was analyzed for alpha and gamma tocopherol content by high-pressure liquid chromatography with fluorescence detection. This article reports the alpha and gamma tocopherol contents of those foods, tocopherol contributions from each food in one sample 2,400-kcal menu, and the mean daily vitamin E activity (milligram alpha tocopherol equivalents) of all seven menus at five caloric levels. Major sources of alpha tocopherol (greater than 10% of the RDA) common to both diets (10 and 30 gm linoleic acid) were olive oil and a few fruits and vegetables. Additional major sources in the 30-gm linoleic acid diets were polyunsaturated fatty acid (PUFA) vegetable oils and margarine. Contrary to a common assumption, increasing the level of PUFA in the menus did not necessarily result in higher milligram equivalents of alpha tocopherol because soybean oil, with a tocopherol composition that is predominantly gamma tocopherol, was the major source of linoleic acid in the diets. Thus, vitamin E activity was not necessarily increased when soybean oil was substituted for a less saturated fat such as olive oil, which has mostly alpha tocopherol.

Liquid-chromatographic determination of alpha- and gamma-tocopherols in erythrocytes, with fluorescence detection

We have adapted to erythrocytes a method for the determination of alpha- and gamma-tocopherols in plasma and platelets. Erythrocytes (50 microL) were extracted with methanol containing tocol (internal standard) and pyrogallol. Tocopherols were partitioned into chloroform, washed, and injected in methanol onto a reversed-phase (C18) "high-performance" liquid-chromatographic column. The mobile phase was methanol/water (99/1 by vol) at a flow rate of 2 mL/min and detection was with a "high-performance" spectrophotofluorometer. The limit of detection for either tocopherol is 0.10 microgram/mL of packed cells. Analytical recoveries ranged from 93 to 104%. Some values for tocopherols in human erythrocytes are presented.

Liquid-chromatographic determination of alpha- and gamma-tocopherols in erythrocytes, with fluorescence detection

We have adapted to erythrocytes a method for the determination of alpha- and gamma-tocopherols in plasma and platelets. Erythrocytes (50 microL) were extracted with methanol containing tocol (internal standard) and pyrogallol. Tocopherols were partitioned into chloroform, washed, and injected in methanol onto a reversed-phase (C18) "high-performance" liquid-chromatographic column. The mobile phase was methanol/water (99/1 by vol) at a flow rate of 2 mL/min and detection was with a "high-performance" spectrophotofluorometer. The limit of detection for either tocopherol is 0.10 microgram/mL of packed cells. Analytical recoveries ranged from 93 to 104%. Some values for tocopherols in human erythrocytes are presented.

Improved direct determination of alpha- and gamma-tocopherols in plasma and platelets by liquid chromatography, with fluorescence detection

Tocopherols extracted from plasma with methanol or from platelets with chloroform/methanol were injected in methanol on a reversed-phase (C18) "high-performance" liquid-chromatographic column and eluted with water/methanol (2/98, by vol) at a flow rate of 1.4 mL/min. A "high-performance" spectrophotofluorometer was used for detection. Analytical recoveries ranged from 89 to 106%. The response was linear to at least 0.3 micrograms of either tocopherol (alpha- or gamma-) applied to the column, and the limit of detection was 0.1 ng. The method was used to measure tocopherols in plasma and platelets from human subjects, and some values are presented.

Improved direct determination of alpha- and gamma-tocopherols in plasma and platelets by liquid chromatography, with fluorescence detection

Tocopherols extracted from plasma with methanol or from platelets with chloroform/methanol were injected in methanol on a reversed-phase (C18) "high-performance" liquid-chromatographic column and eluted with water/methanol (2/98, by vol) at a flow rate of 1.4 mL/min. A "high-performance" spectrophotofluorometer was used for detection. Analytical recoveries ranged from 89 to 106%. The response was linear to at least 0.3 micrograms of either tocopherol (alpha- or gamma-) applied to the column, and the limit of detection was 0.1 ng. The method was used to measure tocopherols in plasma and platelets from human subjects, and some values are presented.

Twice-a-day treatment in the radiotherapeutic management of malignant mixed tumor of the parotid gland: A case report

A patient with a 2,300 gm malignant mixed tumor of the parotid gland had recurrence 19 days post surgery. The recurrent mass failed to respond to daily fractions of 200 rad conventional irradiation four times per week and actually increased in size. A superfractionation scheme was substituted, employing twice-a-day 200 rad at 4-5½ hours intervals three times a week for 2½ weeks. At the completion of treatment, there was a 50 percent regression of the recurrent tumor mass and a 100 percent regression two weeks post irradiation. A protocol using a twice-a-day treatment is discussed.