Biomedical subjects

C Cox

Publications and source records attributed to C Cox.

At least 523 records · Page 29Linked to original sources

PubMedDate not supplied

Urinary 2-thiothiazolidine-4-carboxylic acid (TTCA) as the major urinary marker of carbon disulfide vapor exposure in rats.

Male Sprague-Dawley rats (200-250 g; 60 per exposure group) were exposed to carbon disulfide (CS2) air concentrations of 0, 50, 150, and 500 ppm(v/v) for 6 hr/day, 5 days/week over six months. Following the exposures, nine rats from each exposure group had four sets of cumulated urines collected (between 0-8, 8-16, 16-24, and 24-48 hr). The urinary parameters measured were: 2-thiothiazolidine-4-carboxylic acid (TTCA), total thioethers (TE), and the compounds responsive to the iodine-azide (IA) test. Urinary TTCA elimination obeyed pseudo-first-order, one-compartment model kinetics of half-time (t0.5) 5.2 +/- 0.3 hr up to 16 hr of collection. The elimination of TE within 16 hr had a t0.5 of 8.5 +/- 0.6 hr. TTCA, IA, and TE were correlated highly in the first 16 hr. After 16 hr, the t0.5 for TE lengthened to 13.1 hr. At CS2 concentrations of 50, 150, and 500 ppm, the respective t0.5 for IA-responsive compounds were 12.6, 6.1, and 4.4 hr. TTCA had the highest correlation coefficient and p-value relative to CS2 exposure concentration, and also was the most sensitive, precise, and selective urinary marker.

Administration, Oral↗

PubMedDate not supplied

Neither intraocular grafts of retinal cell homogenates nor live non-retinal neurons produce behavioral recovery in rats with light-damaged retinas.

Previously we have observed that fetal retinal cells grafted to the subretinal space of blind rats produced a functional recovery as determined by testing the visual inhibition of the startle response. Following those studies, we performed experiments to test whether the injection itself, cell by-products, or unrelated neural cells could also produce an effect. Visual function was tested by examining the inhibitory effect of a brief light flash (300 lx) on the acoustic startle response to an immediately following intense noise burst in light blinded Fischer 344 rats. Animals were tested before and after grafts of fetal retinal cell homogenates, dissociated perinatal cerebellar cells, and sham injections in the subretinal space. Behavioral testing continued every 2 wk for 14 wk after the graft. In the pretests, the light flash inhibited the startle response, maximal at intervals of 40-70 ms with recovery thereafter. In contrast, after exposure for 4 wk to fluorescent light (300 lx) and a rest in a normal 12/12 h light/dark environment the rats showed reflex facilitation to the light, maximal at an interval of 110 ms, followed by a late period of reflex inhibition. The light flash had no effect on other rats that had been blinded by bilateral enucleation. Light blinded animals receiving either cerebellar grafts or retinal cell homogenates were no different in performance from their sham injected control animals. The present data suggest that neither subretinal injections of neural cells nor non-specific neurochemical factors are able to elicit a positive behavioral response in visually impaired animals.

Animals↗

PubMedDate not supplied

Storage of human fetal retina in optisol prior to subretinal transplantation.

We have previously reported that Optisol, a commercially available medium (Chiron Vision, Irvine, CA), is a favorable fluid for the storage of neural retina. We now characterize the cell survival and histologic integrity of the tissue following storage and then transplantation. Neural retinas from human fetal eyes obtained within 1 h or pregnancy termination were stored in Optisol-GS medium (containing TC-199 and MEM medium, 2.5% chondroitin sulfate, 1% dextran, HEPES buffer, gentamicin sulfate, 0.1 mmol/L nonessential amino acids, sodium bicarbonate, 1 mmol/L sodium pyruvate, and additional antioxidants), at 4 degrees C for the following time periods: 0, 1, 2, and 7 days, and then tested for viability. Retinas stored for 2 and 7 days were mechanically dissociated and grafted into the eyes of light-damaged Fischer 344 rats (17 animals, 28 eyes). Nontransplanted eyes received injections of vehicle only (5 animals, 6 eyes). All animals were immunosuppressed daily with cyclosporine (10 mg/kg). All experiments were conducted in strict accordance with institutional, federal, and ARVO guidelines. Cell viability averaged 94.8%, 90.2%, 83.2%, and 76.8% at 0, 1, 2, and 7 days storage, respectively. Light microscopy demonstrated that the fetal retina was preserved without evident changes for up to 48 h. Up to 7 days there was a good to very good preservation of the cells in the outer neuroblastic layer. One month after transplantation subretinal grafts of retinal tissue stored for 2 and 7 days in Optisol showed good integration with host retina and initial photoreceptor differentiation. Optisol is a widely used medium for the preservation of human corneas prior to transplantation. Our results show that this medium is also highly suitable for preserving human fetal retinas prior to transplantation.

Animals↗

PubMedDate not supplied

The Alzheimer's Connections Demonstration Program: instituting a national case management program.

The Alzheimer's Connections Demonstration Program was designed to study the most effective ways of linking families with needed services and resources. The five-year demonstration, begun in 1995, funded case management programs in 29 Alzheimer's Association chapters and served 2,313 families. This paper reports on the final two years of the project when all programs were operational. During this period, 800 families were served. The findings indicate that the programs complement the existing chapter services by offering a specific intervention with caregivers. At the end of the demonstration, all chapters planned to continue the program as case management increased their visibility in the community through their ability to offer direct services.

Alzheimer Disease↗

PubMedDate not supplied

The case for village communities for people with learning disabilities.

This article puts forward the arguments for the establishment of village communities for some people with learning disabilities (mental handicap) and shows how they can provide a safe living environment for residents, while at the same time enhancing their quality of life.

Community Health Services↗

PubMedDate not supplied

The experience of therapeutic touch from a nursing perspective.

This article describes the phenomenon of therapeutic touch (TT). Similarities and differences in the experience of the phenomenon from the perspective of a novice practitioner and healthy volunteers are highlighted. A qualitative analysis of findings indicates that the experiences of giving and receiving TT can be classified within two categories: the cognitive (knowing in the widest sense); and conative (instinct and feeling). The key constructs which emerged in this study are associated with feelings such as tingling, warmth, coolness, comfort, peace, calm and security. Formulation of the two main categories, cognitive and conative, emphasize the relationship associated with what is known by the mind and instinctively felt by the body. The holistic aspects associated with the phenomenon of TT are confirmed in the therapeutic relationship which can be formed between the practitioner and recipient during the administration of TT. It is suggested that TT, when provided by the nurse in the clinical setting, can promote feelings of comfort, peace, calm and security among patients.

Adult↗

PubMedDate not supplied

Neonatal intensive care: communication and attachment.

Birth has traditionally been recognized as a family-centred event where immediate exposure to the infant occurs and where the family begins, through direct contact, touch and voice, to form an attachment to the infant. In high-risk pregnancy and delivery, medical and technological advances distance the family from the birth event. This article describes some aspects of a research project with identified factors that facilitate and hinder family and mother attachment to the infant during periods of separation subsequent to premature delivery or other problems which require management in a neonatal intensive care unit (NICU). The project was exploratory. It involved observation of care, participation in care, individual unstructured interviews, focus group interviews and also use of Leske's (1986, 1991a,b) critical care family needs inventory, which was modified and responded to by family members (n = 109) in an attempt to quantify and validate their needs. Six constructs were derived from the inventory and then ranked by mothers (n = 100). The findings from this process were triangulated to observation and interview data in order to confirm factors that facilitate and hinder the process of attachment during family and mother-infant separation. The results of the study imply that when the family and mother are supported by an individualized approach to care and appropriate communication is used, attachment can be facilitated.

Anxiety, Separation↗

PubMedDate not supplied

Lung clearance in Long-Evans rats after inhalation of porous, monodisperse cobalt oxide particles.

Lung clearance of a well-defined uniform and respirable material was conducted to aid in the development of models used to relate inhalation of inorganic hazardous particles to organ doses and bioassay measurements, and in particular to aid in the extrapolation of animal data to humans. In the present study, lung clearance was investigated in Long-Evans rats using monodisperse, porous, 0.8- and 1.7-microns-diameter cobalt oxide (Co3O4) test particles. An advanced inhalation technique for rats using endotracheal intubation yielded exclusive particle deposition in the pulmonary region without external pelt contamination, thus allowing for clearance studies starting directly after inhalation. The kinetics of lung clearance was distinguished between the two dominant clearance mechanisms of mechanical particle transport to the larynx and translocation of dissolved particle material to blood. A particle fraction of about 40% was cleared by short-term particle transport to the larynx, both the long-term particle transport rate and the translocation rate of dissolved particle material given as fractional rates of the retained particle mass in the lungs were not constant with time. The former declined from 0.03 to 0.004 d-1 during 6 months after inhalation. The latter depended on the specific surface area of the porous particles and increased with time from 0.08 and 0.04 d-1 for 0.8- and 1.7-microns particles, respectively. The results obtained were compared to previously reported data obtained from Fischer-344 rats and HMT rats. These were part of a previously reported interspecies comparison of lung clearance followed in seven species, including humans, and using the same batches of Co3O4 test particles. Long-term lung retention was similar in Long-Evans rats and HMT rats but decreased faster for both particle sizes than in Fischer-344 rats, as a result of a significantly faster translocation of dissolved material from the test particles to blood. Mechanical particle transport to the larynx was comparable in all three species.

Aerosols↗

PubMedDate not supplied

Intratracheal instillation versus intratracheal-inhalation of tracer particles for measuring lung clearance function.

Effective elimination of particles deposited in the respiratory tract is an important defense function to protect the organism from potentially adverse effects of inhaled particles. Delivery of radioactively labeled tracer particles and subsequent measurement in vivo of their retention in different regions of the respiratory tract provides an adequate method for characterizing this defensive function. However, the delivery of such tracer particles by inhalation may result in some external contamination of the animals and requires specific protective measures while working with radioactive aerosols. In this study, 85Sr-labeled tracer particles (3 microns) were administered to the lower respiratory tract of rats by intratracheal inhalation to avoid external contamination, and also by intratracheal instillation in order to compare the 2 technique with respect to their suitability for measuring normal and impaired particle clearance rates. It was postulated that particle clearance function in the alveolar region can be determined equally well with intratracheally instilled particles despite their uneven distribution in the lung. For both techniques, rats were anesthesized with halothane and the particles were administered via oral intubation. Retention in the lower respiratory tract of about 30 micrograms (inhalation) and 6 micrograms (instillation) of the administered particles was followed over a period of 180 days by external counting of lung 85Sr-activity in a collimated detection system. To impair alveolar particle clearance rates, groups of rats were subjected to 12 weeks of inhalation exposure prior to delivery of the tracer particles as follows: (1) sham-exposed control; (2) pigment-grade TiO2 particles to induce lung overload: (3) ultrafine TiO2 particles: (4) crystalline SiO2 particles (cristobalite). The following results were obtained: The long-term retention half-times (T1/2) of the tracer particles reflecting alveolar clearance consistently showed the same ranking of the treatment groups whether measured after intratracheal inhalation or instillation. Control values were 66 and 72 days, respectively, and significantly prolonged long-term clearance was measured by both methods for pigment-grade TiO2 (117 and 99 days), ultrafine TiO2 (541 and 600 days) and SiO2 (1901 and 1368 days). Comparison of these values between the two modes of administration of tracer particles showed no significant differences. In contrast, the short-term T1/2 (mucociliary clearance) of the intratracheally instilled tracer particles in the different treatment groups were variable and did not accurately reflect particle clearance from the conducting airways. However, short-term T1/2 after intratracheal inhalation of tracer particles were consistent with fast conducting airway clearance, and mucociliary clearance appears to be stimulated when alveolar clearance is significantly impaired due to particle overload or to effects of cytotoxic particles. The results suggest that intratracheal instillation of a low dose (< or = 10 micrograms) of tracer particles in the rat provides an adequate method for reliably determining effects of inhaled toxicants on alveolar particle clearance function. Further, intratracheal inhalation of tracer particles is useful for measuring both short-term (mucociliary) and long-term (alveolar) particle clearance rates in the lower respiratory tract of the rat.

Administration, Inhalation↗

PubMedDate not supplied

Cyclosporin A potentiates receptor-activated [Ca2+]c increase.

The use of the immunosuppressant cyclosporin A (CsA) is frequently associated with hypertension. Drug-induced local vasoconstriction appears to be responsible for this effect. Using fura-2 and 45Ca2+ efflux techniques, we have examined variations in the cytosolic calcium concentration ([Ca2+]c) in rat aortic smooth muscle cells and have shown that increases in [Ca2+]c after [Arg8]vasopressin, serotonin, endothelin-1 or angiotensin II stimulation were potentiated after preincubation of cells with CsA. This effect was independent of cyclophilin or calcineurin inhibition by CsA. Measurements of inositol phosphates (InsPn) after agonist stimulation showed that CsA also potentiated their formation. As for 45Ca2+ efflux this effect was not related to cyclophilin or calcineurin inhibition. Direct stimulation of G proteins with aluminium tetrafluoride induced an increase in InsPn formation and 45Ca2+ efflux. Neither of these responses was potentiated by CsA. These results indicate that CsA acts on a target upstream of G protein activation, possibly at the receptor level, resulting in a potentiation of InsPn formation and subsequent calcium increase.

Aluminum Compounds↗

PubMedDate not supplied