PubMed Health⌕ Search

Biomedical subjects

T D Johnson

Publications and source records attributed to T D Johnson.

11 recordsLinked to original sources
PubMed1992

The disparity between hypothermic coagulopathy and clotting studies.

Hypothermic patients commonly develop coagulopathy, but the effects of hypothermia on coagulation remain unclear because clinical laboratories routinely perform clotting tests only at 37 degrees C. Measurements of activated partial thromboplastin times (APTT), prothrombin times (PT), and thrombin times (TT) were performed on plasma from normothermic and hypothermic rats at a range of temperatures (25 degrees-37 degrees C) to assess the effects of hypothermia on apparent clotting factor levels and clotting factor activities. In general, clotting times were more severely prolonged when test temperatures were hypothermic than when body temperatures were hypothermic. Indeed, little to no prolongation resulted from body hypothermia alone. These findings reveal the observed disparity between clinically evident hypothermic coagulopathy and near-normal clotting studies. Clotting studies performed at 37 degrees C will not confirm hypothermic coagulopathy. These results indicate that the appropriate treatment for hypothermia-induced coagulopathy is rewarming rather than administration of clotting factors.

Animals↗
PubMed1991

Methamphetamine-induced ischemic colitis.

A 50-year-old woman with acute onset of right lower quadrant pain and hematochezia proved to have segmental ischemic colitis associated with methamphetamine abuse. The diagnosis was established by colonoscopy with biopsy, and abdominal angiography revealed no thrombosis, vasculitis, or vasospasm. The condition resolved within 10 days. Since methamphetamine abuse is increasing, physicians should be aware of its potential to produce intestinal ischemia.

Colitis↗
PubMed1990

Vecuronium for rapid-sequence intubation for cesarean section.

Because succinylcholine may occasionally be contraindicated for rapid-sequence induction in parturients, we studied the use of vecuronium in 21 patients having elective cesarean sections. Eleven patients (group 1) received 10 micrograms/kg vecuronium as a priming dose, followed 4-6 min later by 100 micrograms/kg. Ten patients (group 2) received 200 micrograms/kg vecuronium as a bolus. Onset, the time from the injection of vecuronium to maximal twitch suppression, and clinical duration, the time between vecuronium administration and return to 25% of the control twitch height, were recorded. Umbilical and maternal venous blood samples at delivery were analyzed for vecuronium concentrations. One-minute and 5-min Apgar scores and 1- and 24-h Neurologic and Adaptive Capacity Scores (NACS) were recorded. Individual tests of passive and active tone within the overall NACS profile were compared to evaluate further any residual vecuronium effects in the infants. Onset of neuromuscular blockade was 177 s in group 1 and 175 s in group 2. The corresponding clinical durations were 73 and 115 min. Maternal and umbilical venous vecuronium concentrations were 515 and 73 ng/mL in group 1 and 838 and 107 ng/mL in group 2. Seventy percent of neonates in group 1 had Apgar scores greater than 7 at 1 min, with 100% greater than 7 at 5 min. Corresponding values in group 2 infants were 50% and 80%. Fifty percent of group 1 infants had NACS of 35-40 at 1 h, and 70% at 24 h.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Specific unresponsiveness to skin allografts in burns.

We have examined the potential to provide long-term or even permanent wound coverage in a mouse model of a 30% total body surface area burn using skin allografts. Treatment of the recipient mouse with rabbit anti-mouse thymocyte serum (ATS) followed by donor bone marrow infusion induces a state of specific unresponsiveness to the skin allograft without the need for chronic immunosuppression. Specifically, a B6AF1 mouse receives a burn on Day -2 relative to grafting, ATS on Day -1, and Day +2, a skin allograft from a C3H/He mouse on Day 0, and infusion of C3H/He donor bone marrow on Day +6. We studied three groups of burned mice: Group I, allograft control (n = 5); Group II, allograft plus ATS (n = 12); and Group III, allograft plus ATS and bone marrow infusion (n = 15). Mean graft survival was compared using a one-way analysis of variance and a Student-Newman-Keuls post hoc test. There was no statistical difference in animal mortality among any of the three groups, and there was no evidence of infectious morbidity. Mean skin allograft survival was as follows: Group I, 9 days; Group II, 29 days; and Group III, 66 days (P less than 0.05 vs Group I and II). Nine animals in Group III had intact hair bearing grafts at 90 days when the study was terminated. This study suggests the potential use of induced specific unresponsiveness to skin allografts for wound coverage in thermal injury without use of chronic immunosuppression. In our animal study this was accomplished without increased mortality or apparent infectious morbidity.

Animals↗
PubMed1978

Preparation of [14C]colestipol hydrochloride and its disposition in the human, dog and rat.

Colestipol hydrochloride, a polymeric, ion-exchange type, hypocholesterolemic agent, acting by sequestering bile acids, was labeled with carbon-14. The disposition of the labeled material was studied in the human, dog and rat. The extent of absorption from the gastrointestinal tract, as judged by urinary excretion of radioactivity, was very small and correlated well with the contents of water-soluble and dialyzable materials in the colestipol hydrochloride. Results were consistent with the dialyzable material in the drug being the absorbable species.

Animals↗
PubMed1976

Phenoxybenzamine-a mediator of blood oxygen affinity.

Studies of the effect of phenoxybenzamine on oxygen transport have been concentrated on flow and resistance changes. Previous studies have ignored the possible effects of phenoxybenzamine on the ability of red blood cells to offload oxygen itself. After an initial inhibitory effect phenoxybenzamine greatly enhances the ability of the red cell to offload oxygen under conditions seen at the tissue level. The disparity between P50std and organic phosphate changes found in this and other studies warrants extreme caution to be used in interpreting results where P50 itself is not measured.

Adenosine Triphosphate↗