Search PubMed⌕ Search

Biomedical subjects

D Greenhalgh

Publications and source records attributed to D Greenhalgh.

30 records · Page 2Linked to original sources
PubMed1990

An epidemic model with a density-dependent death rate.

This paper deals with a mathematical model for a disease where the death rate depends on the number of people in the population. This sort of model would be suitable for diseases in developing countries or for diseases amongst animal and insect populations. We also assume that the population under consideration is regulated by the disease so that there is a mortality induced by the disease. We use a compartmental model and perform an equilibrium and stability analysis to find that there is a threshold condition. If the threshold is exceeded, then there is a unique equilibrium with disease present which is locally stable to small perturbations. We conclude by looking at several specific models and seeing how the results relate to previous work.

Animals↗
PubMed1988

Analytical threshold and stability results on age-structured epidemic models with vaccination.

This paper examines mathematical models for common childhood diseases such as measles and rubella and in particular the use of such models to predict whether or not an epidemic pattern of regular recurrent disease incidence will occur. We use age-structured compartmental models which divide the population amongst whom the disease is spreading into classes and use partial differential equations to model the spread of the disease. This paper is particularly concerned with an analytical investigation of the effects of different types of vaccination schemes. We examine possible equilibria and determine the stability of small oscillations about these equilibria. The results are important in predicting the long-term overall level of incidence of disease, in designing immunisation programs and in describing the variations of the incidence of disease about this equilibrium level.

Age Factors↗
PubMed1988

Threshold and stability results for an epidemic model with an age-structured meeting rate.

This paper examines threshold and stability results for simple mathematical models for the transmission of infectious diseases with permanent natural immunity. Examples of such diseases are measles, chicken-pox, hepatitis, and mumps. An important feature of this work is the introduction of an age structure into the population amongst whom the disease is spreading and, in particular, the realization of the fact that the contact rate itself may depend on age. Equilibrium and stability analyses are performed on these models. These results are in part directed towards establishing conditions sufficient for the existence of a nonzero equilibrium disease level to be possible. Conjectures about the existence of a nonzero solution to a set of partial integrodifferential equations are examined. These conditions determine the circumstances under which the disease will persist. Particular emphasis is devoted to the case where the meeting rate depends on age.

Age Factors↗
PubMed1988

Isoflurane in the treatment of asthma.

A 22-month-old child developed severe bronchospasm. Prolonged ventilation of the lungs with isoflurane for 102 hours was used as treatment. The metabolism and fluoride levels obtained are discussed.

Administration, Inhalation↗
PubMed1987

Analytical results on the stability of age-structured recurrent epidemic models.

This paper examines the equilibrium and stability properties of relatively simple mathematical models for the transmission of infectious diseases such as measles, rubella, and mumps. We consider endemic diseases which are recurrent over a long time period. We discuss some simple models which incorporate an age structure into the population amongst whom the disease is spreading, since recent work has shown this feature to be important. The results are relevant in three ways: for predicting the long-term overall level of incidence of disease; for describing the oscillations of the incidence of disease around this equilibrium level; and for designing immunization programmes.

Age Factors↗
PubMed1987

Immunomodulators and wound healing.

The synthetic immunomodulators muramyl dipeptide (MDP), thymopoietin pentapeptide (TP5), and CP-46,665 were examined for their effects on wound healing in mice. We found no differences in wound disruption strength between immunomodulator-treated animals and saline controls on days 11, 14, and 21. The only exception was with high-dose CP-46,665, which produced weakened wounds on day 14 (p less than 0.05) and 21 (p less than 0.01). CP-46,665 was further studied by injecting high and low doses 48 hours before or after wounding. No differences were seen for these groups compared to controls at 11 and 21 days. Finally, to simulate a common clinical situation, mice were subjected to a 10% total body surface area (TBSA) burn to the right paraspinal region. Twenty-four hours later, a left paraspinal incision was performed with simultaneous injection of saline, Corynebacterium parvum (C. parvum), or low-dose TP-5, MDP, or CP-46,665. At 11 days, no detriment in wound healing was found for burned control or any of the immunomodulator-treated animals except in the C. parvum-treated mice, with significantly weakened skin strips (p less than 0.001). While C. parvum may be detrimental to wound healing, the synthetic modulators tested appear to have little effect on wound healing.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1986

Inhibition of wound healing by Corynebacterium parvum.

Corynebacterium parvum (C. parvum), an immunostimulant, was examined for its effects on wound healing in mice. Animals injected intraperitoneally with C. parvum, 1400 micrograms 48 hr prior to wounding had significantly decreased wound strength at 5, 7, 11, 14, and 21 days after wounding compared to saline-injected controls (P less than 0.05-P less than 0.001). Mice injected with C. parvum at 48 or 2 hr before wounding, synchronous with wounding and 2 or 48 hr after wounding had significantly decreased wound disruption strength of 11-day-old wounds (P less than 0.01-P less than 0.001). Formalin fixations of wound strips from C. parvum-treated animals were consistently weaker than similarly treated wound strips from controls (P less than 0.05-P less than 0.01). Histologic analysis of wounds from C. parvum-treated animals revealed decreased amounts of wound collagen and increased inflammatory reaction compared to saline-injected animals. While C. parvum can improve survival following injury or septic challenge, the potential for marked alterations in wound healing may limit its clinical application in surgical and trauma patients.

Animals↗
PubMedDate not supplied

Use of fibrin sealant in thermal injury.

Fibrin glue is hemostatic in skin grafting and other therapeutic situations. This prospective, open-labeled comparative study involved thermally injured patients: 34 patients received fibrin sealant (FS) and 61 did not, at Loyola University Medical Center, Maywood, Illinois, and Shriners Burn Institute, Cincinnati, Ohio. FS-treated patients were 23.6 +/- 16.8 years old, versus 20.8 +/- 16.8 years for controls. The percentage of total body surface areas burn was 10.0% +/- 4.5% in the study patients versus 10.9% +/- 7.9% in the controls. The FS group did not receive packed red blood cell transfusions, albumin infusion, or topical bovine thrombin (TBT). The control group received 1.56 +/- 2.1 units of packed red blood cells, 186 +/- 194 ml 5% albumin, and TBT (20,000 units) 2.6 +/- 0.8 kits during excision and grafting procedures. The estimated blood loss/graft ration was 0.50 +/- 0.30 ml/cm2 (median = 0.46) for the study group versus 0.98 +/- 2.4 ml/cm2 (median = 0.56) for the control group (p = 0.14); for patients more than 16 years of age, this difference was significant (p = 0.03). FS may be a viable alternative to standard hemostatic techniques, because it reduced the need for blood transfusion, alloantigen exposure, and blood-borne viral infection risk. FS also eliminated the need for TBT and epinephrine, did not have an adverse impact on the surgical outcome, and tended to improve the cost differential.

Adolescent↗
PubMedDate not supplied

Return to school as an outcome measure after a burn injury.

Outcome measures have become an important tool to assist with monitoring the efficacy of burn care. One such measurement for children is the time required for them to return to school, as well as their behavior and academic performance in school after a burn injury. The purpose of this study was to relate demographic data with return-to-school time and school performance. Through medical record review and interviews with patients, parents, and school teachers, information was obtained regarding the patient's burn injury, as well as home and school status before and after the burn injury. School information before the burn injury was obtained after patient admission. Schools were contacted 6 months after hospital discharge for data after the burn injury. Thirty-four patients aged 6 to 16 years had their outcomes evaluated from September 1993 to June 1995. Average total body surface area burned was 25.9%; the mean area of full-thickness burn was 17.5%. Length of stay averaged 30.8 days. Sixty-five percent of patients were discharged with splints, and all were discharged with a pressure program. Children returned to school an average of 7.4 days after discharge, and the average number of missed school days was 22. Thirty-four percent of the children had a school reentry visit, and either a phone call, written material, or both were provided in lieu of a visit to the other schools. For this population, burn injury did not appear to impact outcome negatively as it related to a child's return or function in school. These children returned to school rather rapidly after discharge and functioned as well or better after injury. Little loss of grade was noted, and only those children with problems in school before the burn injury had problems after the burn injury. Contact with the child's school before reentry might have assisted with the smooth transition.

Adolescent↗