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Biomedical subjects

R Cross

Publications and source records attributed to R Cross.

54 records · Page 3Linked to original sources
PubMed1986

Effect of duration of lidocaine infusion and route of cimetidine administration on lidocaine pharmacokinetics.

The effects of the duration of lidocaine infusion and the route of cimetidine administration on lidocaine pharmacokinetics were evaluated in a randomized, three-phase crossover study of six healthy men. Lidocaine hydrochloride 100 mg was administered intravenously over two minutes, and plasma lidocaine concentrations were determined before treatment and at various intervals for three hours. Immediately after the three-hour sample was obtained, a second 100-mg dose of lidocaine hydrochloride was given, followed by a 21-hour constant infusion at a rate of 2 mg/min. Plasma lidocaine concentrations were determined at various intervals during the infusion and for eight hours afterward. Urine was collected during the last five hours of the infusion and assayed for lidocaine, monoethylglycinexylidide (MEGX), and glycinexylidide (GX). The following treatments were administered to each subject in a crossover manner: a placebo tablet every six hours, beginning two days before lidocaine administration; cimetidine 300 mg orally every six hours, beginning two days before lidocaine administration; and cimetidine hydrochloride 300 mg i.v. every six hours, beginning one hour before lidocaine administration. Each medication was given until the lidocaine infusion was discontinued. Subjects fasted and remained supine throughout each treatment period. Oral cimetidine increased the area under the concentration-time curve for lidocaine by 14.7% and increased the elimination half-life of lidocaine; i.v. cimetidine did not have a significant effect on lidocaine disposition. Lidocaine clearance was 34% lower under steady-state than single-dose conditions, but the effects of cimetidine on lidocaine disposition were similar under both conditions.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

Histocompatibility antigens and intrauterine fetal growth retardation.

Maternal-fetal antigen compatibility adversely affects fetal and placental weights in animal experiments and is associated with recurrent spontaneous abortion and preeclampsia in human reproduction. HLA A and B types of the mother, father and infant were determined in 30 pregnancies complicated by intrauterine fetal growth retardation (IUGR) and in 32 normal pregnancies. The frequency and degree of antigenic compatibility between the parents and the mothers and their infants were compared between the groups. There was no evidence that IUGR was associated with a significant degree of HLA A and B antigenic compatibility.

Child, Preschool↗
PubMed1985

Delayed effects of Soman: brain glucose use and pathology.

The [14C]-2-deoxyglucose (2-DG) technique was used to determine the delayed effects of Soman, a potent anticholinesterase inhibitor, on local cerebral glucose utilization (LCGU). Rats were given 100 micrograms/kg of Soman (0.9 LD50; i.m.) or saline and LCGU was assessed 24, 48 or 72 hours later. All Soman injected rats had strong, continuous seizures which persisted for at least one hour. At 24 hours post-Soman there was greater than a 2-fold reduction in LCGU in the frontal cortex, cingulate gyrus, anterior and ventral thalamic nuclei, lateral habenula, parietal cortex, lateral geniculate and medial geniculate. On the other hand, the hippocampal structures did not show a significant decrease in LCGU until 48 hours post-Soman exposure. Conspicuous neuropathology was obvious in a number of structures upon inspection of the frozen brain sections, hematoxylin and eosin stained sections or the 2-DG autoradiograms, 24 to 72 hours post soman-exposure. Damage was most severe in the piriform cortex and amygdala. The lateral and ventral thalamic nuclei, many cortical regions and variable segments of the hippocampus were also consistently damaged. We suggest that energy deprivation, inadequate perfusion and/or inadequate calcium sequestration may contribute to the delayed effects following Soman-induced seizures. The 2-deoxyglucose method provides information about the dynamic process of cerebral glucose utilization and serves as a "window" for identifying neuroanatomical structures affected by neurotoxins.

Animals↗
PubMed1984

Comparison of internal jugular and central venous pressure measurements.

The pressure in the internal jugular vein was measured with the head in three different positions using, first, a short cannula and then a catheter with a round occluded end and two side-holes. These pressures were compared with the central venous pressure. In the horizontal position using the catheter, the two venous pressure measurements were similar. With the open-ended cannula, results could be unreliable with the head turned towards the side of cannulation.

Blood Pressure Determination↗
PubMed1983

Brain regional glucose use during Soman-induced seizures.

The (14C)-2-deoxyglucose procedure was used to determine the effects of the potent acetylcholinesterase inhibitor Soman on regional metabolism in the brain. Groups of rats were given 112 micrograms/kg Soman, 84 micrograms/kg Soman, or saline i.m., and 15 min later the (14C)-2-deoxyglucose mapping procedure was initiated. All animals given 112 micrograms/kg Soman and 2 of 6 given 84 micrograms/kg Soman developed seizures that continued throughout the mapping procedure. Very high rates of glucose use occurred in most of the brain regions studied during seizures. The most striking increases occurred in substantia nigra, septum, outer layer of dentate gyrus of the hippocampus, hippocampal body, frontal cortex, caudate, ventral thalamus, parietal cortex, medial geniculate and interpeduncular nucleus. Only the inferior colliculus, superior olivary nucleus and lateral habenula were unaffected by the seizures. The mid layers of cerebral cortex rostral to superior colliculus showed marked reductions in glucose use which may represent inhibition of neuronal activity or functional failure from depleted energy reserves. The animals given 84 micrograms/kg i.m. that did not have seizures had regional glucose use patterns similar to the controls. The results indicate that the brain damage observed by others in Soman treated rats may be in part due to the excessive neuronal stimulation that occurs during the prolonged Soman-induced seizure.

Animals↗
PubMed1983

Soman-induced depression of brain activity in TAB-pretreated rats: 2-deoxyglucose study.

Administration of large doses of Soman (2xLD50) to rats protected with TAB, a mixture of trimedoxime (TMB-4), atropine and benactyzine, results in approximately 2-fold reductions of local cerebral glucose utilization (LCGU) in most brain regions. This is in contrast to the marked increase in LCGU that is observed in conjunction with the seizures associated with an LD50 dose of Soman given to unprotected rats. This study reveals that TAB is effective in protecting against Soman-induced seizures, but only at the expense of a severe decrease in LCGU after Soman exposure.

Animals↗
PubMed1982

Kainic acid alters cholinergic responses in the rat retina: a 2-deoxyglucose study.

Intraocular injections of the neuroexcitatory toxin, kainic acid, did not alter the output of the retinal ganglion cells, as determined by the rate of glucose use in the stratum griseum superficialis of the superior colliculus. However, significant differences were observed in cholinergic interactions of the ganglion cells after kainic acid treatment. Intraocular injection of kainic acid prevented the increase in the stratum griseum superficialis activity typically produced by systemic injection of the acetylcholinesterase inhibitor diisopropylfluorophosphate (DFP). In addition, the retinal ganglion cells were strikingly sensitive to intraocular injections of acetylcholine 1 week after exposure to kainic acid, as reflected in the marked increased glucose utilization in the stratum griseum superficialis. This responsiveness to acetylcholine may be entirely due to the 80% decrease in acetylcholinesterase in the retina observed 1 week after kainic acid exposure or in part to a supersensitivity of the ganglion cells following the period of acetylcholine depletion.

Acetylcholine↗
PubMed1982

Effects of various secretagogues and human carcinoid serum on lymph flow in the cat ileum.

Previous studies from our laboratory indicate that the lymph flow response of the cat ileum to net volume secretion is dependent upon the mechanism involved in the secretory process, i.e, active secretion (cholera toxin) decreases lymph flow while passive fluid secretion (increased portal pressure, plasma dilution) is associated with a rise in lymph flow. In the present study, we examined the effects of ricinoleic acid, vasoactive intestinal polypeptide, theophylline, histamine, and human carcinoid serum on lymph flow in autoperfused segments of cat ileum. Local intraarterial infusion of theophylline, vasoactive intestinal polypeptide, or human carcinoid serum caused lymph flow to decrease. However, intraluminal placement of ricinoleic acid or intraarterial infusion of histamine produced significant increases in lymph flow. The results indicate that the fluid secretion associated with vasoactive intestinal polypeptide, theophylline, and carcinoid serum are consistent with an active process while ricinoleic acid and histamine secretions are associated with a passive component.

Animals↗
PubMed1979

Jejunal monilial bezoar following total gastrectomy.

A case is reported of monilial bezoar involving the jejunum following total gastrectomy in a patient who was neither severely debilitated nor immunosuppressed. This condition should be differentiated from the more commonly occurring postgastrectomy phytobezoar.

Adult↗
PubMed1979

HLA patterns in Australian patients with insulin dependent diabetes mellitus (IDDM).

HLA antigens were determined in 169 Australian patients with insulin dependent diabetes mellitus (IDDM). HLA-B8 (47.9% v. 23.8%) and B15 (18.9% v. 8.2%) were significantly more frequent in the IDDM patients than in 1460 controls. The relative risks for developing IDDM in people carrying these antigens were 2.94 and 2.59 respectively. Carriers of the B8/B15 genotype had a relative risk of 5.48. These HLA associations in Australian IDDM patients are similar to those reported in other predominantly Caucasian populations.

Adolescent↗
PubMed1978

Multiple aneurysm formation as a complication of interventive angiography.

The authors describe a case in which transcatheter embolization was used to treat a large arteriovenous malformation of the scalp (cirsoid aneurysm), with subsequent development of multiple aneurysms at the embolization sites. This previously unreported complication may have far reaching implications in treatment modality selection.

Arteriovenous Fistula↗
PubMedDate not supplied

HLA antigens in four Pacific populations with non-insulin-dependent diabetes mellitus.

HLA antigen distributions in persons with normal and abnormal glucose tolerance were compared in four Pacific populations. The populations included Melanesians from the Fijian Islands, Loyalty Islands and mainland New Caledonia and Polynesians from the Wallis Islands. HLA-DR results are provided for the first time for Pacific groups. In Polynesians, HLA-B22 was increased in frequency in patients with non-insulin-dependent diabetes mellitus and also in persons with impaired glucose tolerance. However, the association was not statistically significant when corrected for the number of antigens tested. A similar increase in HLA-B22, although not significant, was seen in each of the three Melanesian populations with abnormal glucose tolerance. No other consistent increase in any HLA antigen occurred in persons with abnormal plasma glucose concentrations.

Diabetes Mellitus↗