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Biomedical subjects

P Merrill

Publications and source records attributed to P Merrill.

6 recordsLinked to original sources
PubMed1993

Evaluation and revision of a vasopressin/nitroglycerin protocol for use in variceal bleeding.

BACKGROUND: Continuous infusion of IV vasopressin have been widely used to lower portal pressure and reduce bleeding from esophageal varices. Recently, the combination of vasopressin and nitroglycerin has been noted to be superior to vasopressin alone. This is due to the ability of nitroglycerin to reduce the detrimental effects of vasopressin while preserving its beneficial effects. In September 1989 the authors initiated a protocol in the medical intensive care unit of a large university teaching center that directed caregivers in the simultaneous use of vasopressin and nitroglycerin for use in variceal bleeding. OBJECTIVE: To determine whether the protocol was being used correctly and whether the addition of nitroglycerin produced the desired cardiovascular effects. METHOD: Nineteen patients (25 separate episodes) assigned to the vasopressin/nitroglycerin protocol were monitored retrospectively over a 20-month period for a total of 1068 hours of vasopressin/nitroglycerin infusion. Twenty-four patients received nitroglycerin at 10 to 50 micrograms per minute, 13 at 50 to 100 micrograms per minute and 6 at 100 to 400 micrograms per minute. RESULTS: Nitroglycerin dosage was not advanced appropriately in 78% of episodes despite evidence of bradycardia, hypertension and peripheral vasoconstriction. CONCLUSIONS: Revision of the protocol, giving additional guidance to clinicians on assessment and nitroglycerin advancement, was necessary and was accomplished.

Bradycardia↗
PubMed1991

Rabies control in the Republic of the Philippines: benefits and costs of elimination.

We compared the benefits and costs of eliminating animal and human rabies in the Philippines. If rabies had been eliminated in 1988, economic benefits would total P52.8 (US$2.5) million in 1989. These benefits would largely arise from the abolition of expenses associated with rabies prevention: P29.7 (US$1.4) million for animal vaccination, P21.6 (US$1.0) million for human postexposure prophylaxis, and P0.3 (US$0.02) million for animal rabies examinations. Benefits also included P1.2 (US$0.06) million in additional earnings of humans whose death due to rabies would be prevented. Nationwide elimination was estimated to cost between P88.1 (US$4.2) million and P317.2 (US$15.0) million, assuming a canine-to-human ratio of 1:10, vaccine coverage of 60%, and a cost per vaccination of no less than P25 (US$1.19) and no more than P90 (US$4.27). These costs would be recouped 4.1-11.0 years after the initiation of a one-year elimination campaign. A sensitivity analysis showed that an elimination programme would be economically beneficial in all but the most extreme cases.

Animals↗
PubMed1989

Minimum audible angle thresholds obtained under conditions in which the precedence effect is assumed to operate.

Two experiments were conducted to examine the ability of human listeners to localize the "lag" or "echo" source in a precedence effect paradigm. A 5-ms noise burst was presented from a source located between 554-279 cm from the subject. This "lead" source was always located at 0 degrees azimuth. At the same time, one of two sources located at a distance of 610 cm from the subject was also activated with the same 5-ms noise burst. The subject's task was to identify which lag source had been active. Across sessions, the angular distance between the lag sources was varied, so as to allow a determination of the minimum audible angle (MAA) that could be resolved. Tests were run in a room designed to minimize reflections and in a hallway that was acoustically quite complex. No systematic differences in MAA thresholds were observed as a function of the environment employed. MAA thresholds obtained without the signal from the lead speaker were less than 1 degree for four of the five subjects tested. The precedence effect, as measured by the change in the MAA threshold, appears to have only a modest influence on localization performance. Under conditions in which the lead source was concurrently active, the thresholds were generally elevated by only 2 degrees-4 degrees. A reduction of this magnitude in the ability to resolve the position of the lag source does not seem to be sufficient, in itself, to account for the excellent localization performance frequently observed in reflective environments.

Acoustic Stimulation↗
PubMed1984

Inhibition of mouse peritoneal macrophage DNA synthesis by infection with the arenavirus Pichinde.

Macrophage DNA synthesis and proliferation occur during the development of cell-mediated immunity and in the early nonspecific reaction to infection. Arenaviruses have a predilection for infection of cells of the reticuloendothelial system, and in this study we have examined the effect of the arenavirus Pichinde on macrophage DNA synthesis. We have found that infection of mouse peritoneal macrophages with Pichinde caused a profound dose-dependent inhibition of the DNA synthesis induced by macrophage growth factor-colony stimulating factor. At a multiplicity of inoculum of 5, there is a 75 to 95% inhibition of DNA synthesis. Viable virus is necessary for inhibition since Pichinde inactivated by heat or cobalt irradiation had no effect. Similarly, virus pretreated with an antiserum to Pichinde was without inhibitory effect. Inhibition was demonstrated by measuring DNA synthesis spectrofluorometrically as well as by [3H]thymidine incorporation. The inhibition of DNA synthesis was not associated with any cytopathology. There was no evidence that the inhibition was due to soluble factors, such as prostaglandins or interferon, released by infected cells. These studies demonstrate, for the first time in vitro, a significant alteration in macrophage function caused by infection with an arenavirus. It is possible that inhibition of macrophage proliferation represents a mechanism by which some microorganisms interfere with host resistance.

Animals↗
PubMedDate not supplied

Oncologic emergencies.

Oncologic emergencies may occur in patients who have no prior diagnosis of malignancy as well as in patients who are known to have cancer. It is important for the primary care practitioner to consider an oncologic cause for symptoms or problems that may bring a patient into the office. These symptoms often are vague and could be indicative of numerous problems frequently associated with individuals who have cancer. A brief overview of the most common oncologic emergencies is given, along with differential diagnostic possibilities and management strategies.

Aged↗