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Biomedical subjects

S R Jones

Publications and source records attributed to S R Jones.

189 records · Page 11Linked to original sources
PubMedDate not supplied

The occurrence and mechanisms of innate immunity against parasites in fish.

Parasitic infections in teleost fish are limited by constitutive innate defence mechanisms that render the host refractory or reduce the severity of infection. Controlled challenge trials using naive animals provide indirect evidence of innate immunity as well as identifying the host range or specificity of a parasite, often when specific details of defence mechanism(s) are lacking. Examples of parasites for which innate immunity may be inferred from cross-infectivity studies include Gyrodactylus spp., Lepeophtheirus salmonis, Cryptobia spp., Trypanosoma spp., Ceratomyxa shasta, Myxobolus cerebralis and Kudoa thyrsites. Recent studies however, have begun to clarify the relative roles of innate and acquired immunity against parasitic infection in teleosts by recognizing the presence and significance of specific innate effector mechanisms. The physico-chemical characeristics of skin mucus, the presence of bioactive substances including lysozyme, complement, C-reactive protein, haemolysins and lectins and the epidermal migration of inflammatory cells and their secretions may affect the establishment and proliferation of ectoparasitic copepods, ciliates or monogenea. Similarly in refractory species, haematozoic parasites are lysed via the alternative complement pathway and in susceptible and refractory hosts, protease inhibitors associated with the plasma neutralize proteolytic virulence factors. Detailed knowledge of innate resistance mechanisms against histiozoic parasites are lacking although non-specific cytotoxic lymphoid cells and macrophages probably play a role. The demonstration in certain disease models that innate resistance traits are under genetic control and may be inherited in a simple Mendelian fashion suggests opportunities for selective breeding for resistance against parasitic disease. Beyond a small number of well-described models however, research programs focussing on innate immunity against parasites in fish are lacking. Given the relative importance of innate immunity in fish, particularly as disease losses continue to have an economic impact in aquaculture, this area deserves considerable attention.

Animals↗
PubMedDate not supplied

Nosocomial urinary tract infection: a prospective evaluation of 108 catheterized patients.

This study describes the evaluation of 108 patients who had indwelling urethral catheters for acute medical and surgical indications. Patients were evaluated daily, and cultures from bladders and drainage bags were obtained. Appropriateness for continuing catheterization was assessed using preset criteria. Twenty-five patients developed urinary tract infections. Exposure to antibiotics and a shorter duration of catheterization were the only factors that correlated significantly with a delayed onset or decreased prevalence of infection. Factors found to have insignificant effects included age, sex, maintenance of the closed system, underlying host disease status, catheter type, and reason for catheterization. No collection systems with one way valves were used, but significantly colony counts in drainage bag urine preceded urinary tract infection in only two patients. Thirty-six percent of the total 562 catheter days were judged unnecessary. A major emphasis must be placed on prompt catheter removal if the prevalence of nosocomial urinary tract infections is to be reduced substantially in a cost-effective manner.

Anti-Bacterial Agents↗
PubMedDate not supplied

Alpha-frequency rhythms desynchronize over long cortical distances: a modeling study.

Neocortical networks of excitatory and inhibitory neurons can display alpha(a)-frequency rhythms when an animal is in a resting or unfocused state. Unlike some gamma- and beta-frequency rhythms, experimental observations in cats have shown that these alpha-frequency rhythms need not synchronize over long cortical distances. Here, we develop a network model of synaptically coupled excitatory and inhibitory cells to study this asynchrony. The cells of the local circuit are modeled on the neurons found in layer V of the neocortex where alpha-frequency rhythms are thought to originate. Cortical distance is represented by a pair of local circuits coupled with a delay in synaptic propagation. Mathematical analysis of this model reveals that the h and T currents present in layer V pyramidal (excitatory) cells not only produce and regulate the alpha-frequency rhythm but also lead to the occurrence of spatial asynchrony. In particular, these inward currents cause excitation and inhibition to have nonintuitive effects in the network, with excitation delaying and inhibition advancing the firing time of cells; these reversed effects create the asynchrony. Moreover, increased excitatory to excitatory connections can lead to further desynchronization. However, the local rhythms have the property that, in the absence of excitatory to excitatory connections, if the participating cells are brought close to synchrony (for example, by common input), they will remain close to synchrony for a substantial time.

Action Potentials↗
PubMedDate not supplied

The effect of an educational program upon hospital antibiotic use.

The effect of an educational program on the use of antibiotics was studied in a university-affiliated Veterans Administration Hospital. Following an initial survey of antibiotic usage, educational presentations of the collected data were made to the hospital staff which included specific prescribing errors and alternative recommendations. Then, another survey was conducted. Measurable changes following the educational presentations were limited to decreasing costs of unjustified antibiotic use. An effect was noted in decreasing unjustified use of antibiotics in prophylactic situations, but this remained the most common misuse. Thus, an educational program directed at specific prescribing errors produced little noticeable effect on the use of antibiotics in a university-affiliated hospital. The study indicates that more direct measures, such as control of use of particular antibiotics, may be required to produce a meaningful change in prescribing practices.

Anti-Bacterial Agents↗
PubMedDate not supplied

Evaluation of a breath operated powder inhaler.

A randomized, double-blind, double-dummy crossover study on 42 asthmatics was carried out to compare the single dose effects of salbutamol administered from the widely used metered dose inhaler and a breath operated system (Diskhaler). The bronchodilator response (change in forced expiratory volume in the first second) was almost identical for the two systems. The Diskhaler system however, since it is breath operated, obviates the need for hand-breath coordination.

Adolescent↗