Increased levels of diadenosine polyphosphates in dry eye

PURPOSE: To analyze the levels of the diadenosine polyphosphates Ap4A and Ap5A in tears, in a set of control subjects and in groups of symptomatic and nonsymptomatic persons with dry eye. METHODS: Ninety-seven subjects participated in the study. The subjects were divided into five experimental groups: control subjects; symptomatic patients with normal tear secretion; symptomatic patients with low tear secretion; forced blink; and corneal mechanical stimulation provided by a gas esthesiometer. The Schirmer I test was used to measure and collect tear secretions from each subject. All samples were processed by high pressure liquid chromatography (HPLC) and their Ap4A and Ap5A levels determined. RESULTS: The levels of Ap4A and Ap5A in tears were greater in all symptomatic patients than in control subjects, especially in symptomatic subjects with low tear secretion. Within the symptomatic subjects with normal tear secretion, significant differences in concentrations of Ap4A and Ap5A were found between men and women. In the forced blink experiments, concentrations of the Ap4A and Ap5A rose with increasing blink frequency. When the cornea was mechanically stimulated, the levels of Ap4A and Ap5A rose significantly during both moderate and high-flow rate tests. CONCLUSIONS: The increased levels of Ap4A and Ap5A in tears of patients with dry eye allow these dinucleotides to be used as objective biomarkers in dry eye conditions.     

Tear secretion induced by selective stimulation of corneal and conjunctival sensory nerve fibers

PURPOSE: To measure the increase in tear secretion evoked by selective stimulation of the different populations of sensory receptors of the cornea and conjunctiva by using moderate and intense mechanical, chemical, and cold stimuli. METHODS: Six healthy subjects participated in the study. Tear secretion was measured in both eyes by the Schirmer's test conducted under control conditions and after stimulation of the center of the cornea and the temporal conjunctiva with a gas esthesiometer. Mechanical stimulation consisted in three pulses of 3 seconds' duration of warmed air (at 34 degrees C on the eye surface) applied at moderate (170 mL/min) and high (260 mL/min) flow rates. Cold thermal stimulation was made with cooled air that produced a corneal temperature drop of -1 degrees C or -4.5 degrees C. Chemical (acidic) stimulation was performed with a jet of gas containing a mixture of 80% CO(2) in air. RESULTS: The basal volume of tear secretion increased significantly (P < 0.05, paired t-test) after stimulation of the cornea with high-flow mechanical stimuli (260 mL/min), intense cooling pulses (-4.5 degrees C), and chemical stimulation (80% CO(2)). The same stimuli were ineffective when applied to the conjunctiva. Moderate mechanical (170 mL/min) and cold (-1 degrees C) stimulation of the cornea or the conjunctiva did not change significantly the volume of tear secretion. CONCLUSIONS: Reflex tear secretion caused by corneal stimulation seems to be chiefly due to activation of corneal polymodal nociceptors, whereas selective excitation of corneal mechanonociceptors or cold receptors appears to be less effective in evoking an augmented lacrimal secretion. Conjunctival receptors stimulated at equivalent levels do not evoke an increased tear secretion.     

Effects of dinucleoside polyphosphates on trabecular meshwork cells and aqueous humor outflow facility

The most important risk factor for the development of glaucoma is elevated intraocular pressure (IOP). Hypotensive drugs decrease IOP, preventing optic nerve damage and further vision loss. The balance between aqueous humor (AH) production and drainage determines IOP, and problems in AH outflow pathways are associated with open-angle glaucoma development. Previous studies have shown the presence of diadenosine tetraphosphate (Ap(4)A) and pentaphosphate (Ap(5)A) in the AH. Topic application of Ap(4)A to the cornea decreased IOP, whereas Ap(5)A increased it. Because dinucleoside polyphosphates stimulate P2Y purinergic receptors, we studied their presence in trabecular meshwork (TM) cells. Additionally, the effects of diadenosine polyphosphates (Ap(n)As; n = 3-5) and Up(4)U (P(1),P(4)-(diuridine 5')-tetraphosphate; INS365) in outflow facility were tested. P2Y(1), P2Y(2), and P2Y(4) receptors were detected in TM cells by Western blot and immunocytochemistry. In TM cells, Ap(3)A, Ap(4)A, and Ap(5)A induced discrete intracellular calcium concentration ([Ca(2+)](i)) mobilizations compared with higher and more sustained [Ca(2+)](i) mobilizations after Up(4)U application. In bovine ocular anterior segments perfused at constant pressure, 1 microM Ap(3)A or Ap(4)A increased outflow facility, whereas Up(4)U or Ap(5)A did not modify it. 2-MeSADP, a selective P2Y(1) agonist, induced outflow facility increases similar to those obtained after Ap(3)A and Ap(4)A, and these were prevented by addition of the selective P2Y(1) receptor antagonist MRS-2179 (2'-deoxy-N(6)-methyladenosine-3',5'-diphosphate). Our results demonstrate that the hypotensive effect of Ap(4)A and other dinucleotides is mediated, at least in part, by increasing trabecular outflow facility through activation of P2Y(1) receptors. The latter would seem to be an interesting target in the development of antiglaucomatous drugs to selectively increase AH outflow.     

The experience of the family caregivers' role: a qualitative study

In Ireland, there is a dearth of research exploring the perceived health and social care needs and experiences of family caregivers of older people. In response, this research study was conducted to explore the profile, role and needs of family caregivers as a means of understanding their experience of caring. The study also set out to identify coping strategies employed by caregivers and explore positive aspects of the caring relationship in relation to quality of life, information needs, day care and respite care, transport and emotional support. A multimethod approach used interviews, focus groups and postal questionnaires. In the main study a pretested questionnaire, comprising closed and open questions was used with a stratified, systematically randomized sample of caregivers in urban and rural home care settings, of which 52% of respondents to the questionnaire volunteered to partake in in-depth interviews. This article per deals predominantly with the findings arising from 10 in-depth qualitative interviews. The data yielded a rich and meaningful picture of the caregiving experience, profiling the complex nature of this diverse and multifaceted role. Findings showed that three main categories emanated from the data: the caring role-context and attitudes, the impact of caring and the need to support the carers' role. The need to develop continually an understanding of the effectiveness of specific health and social care interventions was also of paramount importance. The anticipated continuing demand for family care means that caregivers' needs and perspectives need to be integrated into future service planning and decision-making processes, in partnership with statutory and voluntary bodies. While this was the first study of its type in Ireland, the issues raised reflect the findings of other published studies and have important lessons for family carers and health care practitioners generally.     

Morphogenesis of fowlpox virus in a baby hamster kidney cell line

Fowlpox virus (FWPV) recombinant vaccines are presently being tested as an antihuman immunodeficiency virus vaccine for humans. However, biosafety, as well as the morphogenesis of FWPV in mammalian cells, are not well understood. Currently, electron microscopy is the method of choice for analyzing virus morphogenesis in cell lines. In this study, four different electron microscopic techniques were used to study FWPV morphogenesis in the Syrian baby hamster kidney (BHK-21) cell line: direct negative stain electron microscopy, ultrathin section transmission electron microscopy, cryoimmunoelectron microscopy, and scanning electron microscopy. The study showed matured viruses, as well as other stages of fowlpox virus maturation, in BHK-21 cells that led to productive virus multiplication. A number of virus-containing vesicles and plasma membrane-associated mature viruses at an early stage in the budding process were observed. In addition, intracellular mature virus was observed in layers of the trans-Golgi network, a characteristic of intracellular mature virus wrapping that results in the formation of intracellular enveloped virus. The size and morphology of FWPV observed in this study are comparable with previously published data. This study presents the first morphological evidence for the release of FWPV by budding in BHK-21 cells.This work was presented in part as a late-breaking poster at the Microscopy and Microanalysis Congress in Quebec City, Canada, Aug. 4–8, 2002     

Endemicity of vesical schistosomiasis in the Ebonyi Benue river valley,south eastern Nigeria

The investigation on the prevalence of patent and clinically severe infections with Schistosoma haematobium was carried out amongst inhabitants of Ebonyi Benue river valley, South Eastern Nigeria between August 2000 and June 2001. The inhabitants are predominantly farmers. Of the 3296 subjects examined from 15 randomly selected villages in the valley, 776 (23.5%) were excreting the eggs of S. haematobium in their urine. Infection rates varied between 18.9% and 30.6%. The severity of infection calculated by arithmetic mean egg counts (AMEC) and geometric mean egg counts (GMEC) varied significantly between the age groups and the villages (P < 0.05). The prevalence and severity of infection increased with age from 0 to 25 years and decreased thereafter. Symptoms associated with the disease include visible hematuria (63.1%), suprapubic pain (10.3%) and stranguary (9.9%). While 65 positive persons had more than one symptom, 64 of the positive persons had no noticeable symptoms. Visible hematuria showed moderate sensitivity and high specificity for the disease. Female genital schistosomiasis (FGS) of the lower reproductive tract was recorded in 19 females of child bearing age that complained of severe suprapubic pain. Eight snail species were recorded in the stagnant ponds and both Bulinus globosus and B. truncatus were infected with schistosome cercariae. The factors contributing to these observations and feasible control measures are discussed.     

Concomitant bacteria in the blood of malaria patients in Owerri, southeastern Nigeria

The presence of concomitant bacteria was assessed in the blood of 125 malaria positive patients and 60 malaria negative controls, resident in Owerri, southeastern Nigeria. Blood samples were cultured in MacConkey, Chocolate and Blood agar, respectively using oxoid signal system after the manufacturer's instructions. Blood cultures of 44 (35.2%) of the 125 malaria positive patients had bacterial growth while none was observed in the blood cultures of malaria negative patients. The bacteria species identified included: Staphylococcus aureus 4 (3.2%), Escherichia coli 3 (2.4%) Salmonella typhi 25 (20%), Klebsiella pneumoniae 10 (2.4%) and Pseudomonas aeruginosa 2 (1.6%). The presence of concomitant bacteria in malaria-positive cases usually results in persistence of malaria-like symptoms after treatment with antimalarials and subsequently taken as resistance of the parasites to the particular drugs in question. The significance of concomitant bacteria in the management of malaria should be given priority.     

The prevalence, intensity and clinical manifestations of Onchocerca volvulus infection in Toro local government area of Bauchi State, Nigeria

Between January and October 1994, a study of the prevalence, intensity and clinical manifestations of onchocerciasis in nine communities of Toro local government area of Bauchi State, Nigeria was undertaken using the skin-snip method. Of the 1117 inhabitants examined, 188 (16.8 %) were positive for microfilariae of Onchocerca volvulus. The prevalence of onchocerciasis was significantly higher (P < 0.05) among males than females, in subjects 21 years of age and above than in those in the first two decades of life, in nomads, farmers, hunters and fishermen than smiths and traders. Intensity of infection was light, not exceeding a geometric mean of 5.3 microfilaria per 2 mm skin bite. Preponderance of positive cases below 20 years presented no chronic signs. Conversely, persons above 20 years had higher microfilaria counts which coincides with the period when most clinical signs manifest. Microfilarial-rate and -density in relation to age were closely associated (r = 0.75, P < 0.001). The need for a sustained mass distribution of Mectizan in these communities is highlighted.