Evaluation of acetaminophen absorption in horses with experimentally induced delayed gastric emptying

OBJECTIVE: To evaluate the correlation between the half-time of liquid-phase gastric emptying (T50) determined by use of nuclear scintigraphy, using technetiumTc 99m pentetate, and absorption variables of orally administered acetaminophen in horses with experimentally delayed gastric emptying. ANIMALS: 6 mature horses. PROCEDURE: Delayed gastric emptying was induced by IV injection of atropine sulfate. Twenty minutes later, acetaminophen and technetium Tc 99m pentetate were administered simultaneously via nasogastric tube. Serial lateral images of the stomach region were obtained, using a gamma camera. Power exponential curves were used for estimation of T50 and modified R2 values for estimation of goodness-of-fit of the data. Serial serum samples were obtained, and acetaminophen concentration was determined, using fluorescence polarization immunoassay. Maximum serum concentration (Cmax), time to reach maximum serum concentration (Tmax), area under the curve for 480 minutes, and the appearance rate constant were determined, using a parameter estimation program. Correlations were calculated, using a Spearman rank correlation coefficient. RESULTS: A significant correlation was detected between T50 determined by use of scintigraphy and Tmax determined by use of acetaminophen absorption. Correlation between T50 and other absorption variables of acetaminophen was not significant. CONCLUSIONS AND CLINICAL RELEVANCE: The acetaminophen absorption method was a valid technique in this model of delayed gastric emptying in horses. The method may be a valuable tool for use in research as well as in clinical evaluation of gastric emptying in horses.     

The effects of xylazine,detomidine, acepromazine and butorphanol on equine solid phase gastric emptying rate

The aim of this study was to measure the effects of specific commonly used sedative protocols on equine solid phase gastric emptying rate, using the 13C-octanoic acid breath test (13C-OABT). The gastric emptying of a standard 13C-labelled test meal was measured once weekly in 8 mature horses over two 4 week treatment periods. Each horse acted as its own control. In treatment Period 1, saline (2 ml i.v.), xylazine (0.5 mg/kg i.v.), detomidine (0.01 mg/kg i.v.) or detomidine/butorphanol combination (0.01/0.02 mg/kg i.v.) was administered in randomised order after ingestion of the test meal. During treatment Period 2, test meal consumption was followed by saline, xylazine (1.0 mg/kg i.v.), or detomidine (0.03 mg/kg i.v.) administration, or preceded by acepromazine (0.05 mg/kg i.m.) in randomised order. The 13C:12C ratio of sequential expiratory breath samples was determined by isotope ratio mass spectrometry, and used to measure the gastric half-emptying time, t 1/2, and duration of the lag phase, t lag, for each of the 64 tests. In treatment Period 1, detomidine/butorphanol prolonged both t 1/2 and t lag with respect to xylazine 0.5 mg/kg and the saline control (P < 0.05). In Period 2, detomidine 0.03 mg/kg delayed each parameter with respect to saline, acepromazine and xylazine 1.0 mg/kg (P < 0.001). Xylazine 1.0 mg/kg also lengthened t lag relative to the saline control (P = 0.0004), but did not cause a significant change in t 1/2. Comparison of treatment periods showed that the inhibitory effect of detomidine on gastric emptying rate was dose related (P<0.05). These findings may have clinical significance for case selection when these agents are used for purposes of sedation and/or analgesia.     

AIDS research. The odd intersection of HIV and scrub typhus

Can contracting another disease help suppress HIV? Researchers report intriguing new findings suggesting that a disease called scrub typhus may offer novel leads to developing anti-HIV treatments and vaccines.     

Ground zero: AIDS research in Africa

More and more European and North American AIDS researchers are coming to sub-Saharan Africa, which is home to a whopping 70% of all HIV-infected people. These investigators are collaborating with local researchers on projects that aim to slow both HIV's spread and the course of disease in the millions already infected. But most African countries--constrained by limited resources, weak infrastructures, social mores, and political inaction--have grave difficulties translating research insights into prevention and treatment strategies.     

Is AIDS in Africa a distinct disease?

In Africa, opportunistic infections, transmission patterns, and viral subtypes differ from what is seen in the AIDS epidemics of the United States and Europe, yet 2 decades into the epidemic, AIDS researchers have only a shaky handle on the fundamental question: What accounts for these differences? The answers have potentially important implications for both prevention and treatment strategies.     

Balancing the collaboration equation

Most African countries can't afford to support much research themselves, so the vast majority of studies of HIV/AIDS are being conducted in collaboration with scientists from the developed world. These partnerships have brought major benefits, but inherent inequalities can cause tensions and require constant give-and-take from both sides. An inside look at three veteran marriages between African AIDS researchers and foreign colleagues illustrates the benefits--and stresses--of partnership.     

Profile. Preventing infections with today's tools

With no vaccine in sight powerful enough to halt the spread of HIV, Africa is left with one strategy to combat the epidemic: prevention. The University of Manitoba's Frank Plummer, who oversees a large research collaboration in Nairobi, Kenya, says his group has identified a half-dozen effective interventions to lower HIV transmission rates, but "the scale at which they're implemented is tiny."     

Profile: McIntyre and Gray have a will and a way

At the Chris Hani Baragwanath Hospital here, where HIV infects more than 20% of the 17,000 pregnant women who give birth here each year, pediatrician Glenda Gray and obstetrician James McIntyre aggressively try to help HIV-infected pregnant women stop the virus from infecting their babies.