Rheumatoid-like joint lesions in rabbits injected intravenously with bovine serum

Rheumatoid-like synovial lesions have been produced experimentally in 21% of rabbits receiving intravenous injections of bovine serum by various regimens. They were characterized by lining cell hyperplasia, accumulations, often follicular, of lymphocytes and plasma cells just under the lining layer, sometimes with extensive fibroplasia and pannus formation with cartilage erosion.     

Reduced surface tension in lungs of fetal rabbits injected with pilocarpine

The kinetics of glucokinase from rat liver were studied over wide ranges of glucose and MgATP2- concentrations. The initial rate shows a co-operative dependence on the glucose concentration, with Hill coefficients in the range 1.2-1.5. The degree of glucose co-operativity increases with the MgATP2- concentration, but no co-operativity was detected for the dependence of the rate on the MgATP2- concentration. The effects observed occur at physiologically reasonable concentrations of glucose and MgATP2- and are consistent with the presumed function of glucokinase in maintaining a constant concentration of glucose in the blood.     

The qualitative evaluation of the pharmacokinetics of subconjunctivally injected antifungal agents in rabbits

Dutch-belted rabbits with corneal epithelium either intact or debrided were injected subconjunctivally with 300 microliters of one of six antifungal agents: 10 mg/ml miconazole, 5 mg/ml fluconazole, 5 mg/ml ketoconazole, 2.5 mg/ml itraconazole, and 5 mg/ml amphotericin B. At intervals of 10 min to 96 h after injection, animals were killed and corneas removed at the limbus. Three vertical strips from the right cornea and four contiguous 3-mm disks trephined from the central vertical axis of the left cornea were placed on agar plates seeded with an appropriate indicator organism. After 24 h of incubation, the zones of inhibition were measured. For itraconazole, miconazole, fluconazole, saperconazole, and ketoconazole, central corneal levels peaked by 2 h in normal and debrided corneas. Little or no drug was detectable after 4-8 h, except for itraconazole, which persisted in the cornea for at least 24 h in both normal and debrided corneas. Peak levels of amphotericin B in the central cornea were achieved after 2 h in rabbits with debrided corneas, with no drug activity measured after 8 h. There were no detectable levels of drug found in the central corneas of rabbits with intact corneal epithelium. On the basis of this pilot study, the method offers a rapid approach to the screening of antifungal agents for possible use by subconjunctival injection.     

The effects of experimental malnutrition on albumin metabolism and distribution in rabbits

In order to determine the extent to which the concentration of albumin in plasma is maintained at the expense of the extravascular pool during protein-energy malnutrition, the rates of exchange between albumin in plasma (IA) and the extravascular pool (EA) and consequently the distribution of albumin between intravascular and extravascular pools (expressed as EA:IA) were measured in protein-energy-depleted and control rabbits. The fractional rates of synthesis (FSR) and catabolism (FCR), the concentration of albumin and the plasma volume (PV) were also measured. In animals in which protein-energy intake was reduced by 58% the concentration of albumin in plasma remained unchanged, whereas FCR decreased by 38% and FSR by 30%. No significant changes in EA:IA or PV were found. We conclude that albumin concentration during protein-energy depletion is not maintained at the expense of extravascular albumin, but by parallel changes in the rates of catabolism and synthesis.     

Studies on metabolism of trazodone. IV. Intestinal absorption in rats and rabbits

The absorption rates are the same in rats and rabbits when [14C]trazodone HCl is injected into the duodenum of animals with pyloric vein cannulation. 2. The absorption of trazodone from the duodenum of rats is rapid in comparison with that of imipramine. 3. The residual food content of the rabbit stomach after fasting delay the overall rate of trazodone absorption by markedly decreasing transit rate from the stomach to the small intestine.     

Basal metabolism of weight-stable chronically undernourished men and women: lack of metabolic adaptation and ethnic differences

The purpose of this study was to investigate whether weight-stable chronically energy-deficient subjects exhibit evidence of metabolic adaptation and to establish whether international predictive equations overestimate the basal metabolic rate (BMR) of tropical populations. BMR, body weight, height, and fat-free mass (FFM) by underwater weighing were measured in healthy, physically active urban dwellers of low socioeconomic status (178 men and women aged 22-38 y) in Bangalore, Southern India. Subjects were selected on the basis of body mass index (BMI; in kg/m2) and classified in three groups: severely undernourished (BMI < 17.0; n = 30 men, n = 25 women), marginally undernourished (BMI = 17.0-18.5; n = 31 men, n = 30 women), and well nourished (BMI > 18.5; n = 27 men, n = 35 women). The BMR of the well-nourished group, expressed in absolute terms (6.20 and 5.18 MJ/d for men and women, respectively), was significantly higher (P < 0.000) than that of the severely undernourished group (5.72 and 4.64 MJ/d for men and women, respectively). Normalizing BMR for either body weight or FFM by analysis of covariance abolished all differences. The mean BMR of the low-BMI study group was substantially higher (11-14%) than reported previously for undernourished Indian adults. The BMR of both men and women, regardless of their nutritional status, was accurately estimated by age- and sex-specific FAO/WHO/UNU equations. These findings suggest the absence of an enhanced metabolic response in weight-stable chronically undernourished adults. This is in contrast with earlier reports, and supports more recent views. The study also provides evidence of the absence of ethnic-specific energy turnover in Indians.     

Overexpression of human lecithin:cholesterol acyltransferase in cholesterol-fed rabbits: LDL metabolism and HDL metabolism are affected in a gene dose-dependent manner

Lecithin:cholesterol acyltransferase (LCAT) is an enzyme well known for its involvement in the intravascular metabolism of high density lipoproteins; however, its role in the regulation of apolipoprotein (apo) B-containing lipoproteins remains elusive. The present study was designed to investigate the metabolic mechanisms responsible for the differential lipoprotein response observed between cholesterol-fed hLCAT transgenic and control rabbits. 131I-labeled HDL apoA-I and 125I-labeled LDL kinetics were assessed in age- and sex-matched groups of rabbits with high (HE), low (LE), or no hLCAT expression after 6 weeks on a 0.3% cholesterol diet. In HE, the mean total cholesterol concentration on this diet, mg/dl (230 +/- 50), was not significantly different from that of either LE (313 +/- 46) or controls (332 +/- 52) due to the elevated level of HDL-C observed in HE (127 +/- 19), as compared with both LE (100 +/- 33) and controls (31 +/- 4). In contrast, the mean nonHDL-C concentration for HE (103 +/- 33) was much lower than that for either LE (213 +/- 39) or controls (301 +/- 55). FPLC analysis of plasma confirmed that HDL was the predominant lipoprotein class in HE on the cholesterol diet, whereas cholesteryl ester-rich, apoB-containing lipoproteins characterized the plasma of LE and, most notably, of controls. In vivo kinetic experiments demonstrated that the differences in HDL levels noted between the three groups were attributable to distinctive rates of apoA-I catabolism, with the mean fractional catabolic rate (FCR, d-1) of apoA-I slowest in HE (0.282 +/- 0.03), followed by LE (0.340 +/- 0.01) and controls (0.496 +/- 0.04). A similar, but opposite, pattern was observed for nonHDL-C levels and LDL metabolism (h-1), such that HE had the lowest nonHDL-C levels with the fastest rate of clearance (0.131 +/- 0.027), followed by LE (0.057 +/- 0.009) and controls (0.031 +/- 0.001). Strong correlations were noted between LCAT activity and both apoA-I (r= -0.868, P < 0.01) and LDL (r = 0.670, P = 0.06) FCR, indicating that LCAT activity played a major role in the mediation of lipoprotein metabolism. In summary, these data are the first to show that LCAT overexpression can regulate both LDL and HDL metabolism in cholesterol-fed rabbits and provide a potential explanation for the prevention of diet-induced atherosclerosis observed in our previous study.     

Sex hormones and metabolism of glycosaminoglycans. I. Effect of orchidectomy and administration of testosterone in rabbits

The effect of orchidectomy in male rabbits and administration of testosterone to orchidectomized animals on the metabolism of glycosaminoglycans (GAG) has been studied. The response of the different GAG fractions in the aorta varies with the nature of the GAG, and in some cases is different in different segments of the aorta. Orchidectomy produced an increase in hyaluronic acid fraction, decrease in heparin sulphate fraction, and no response in the chondroitin sulphate A fraction in the aortic arch, thoracic aorta, and abdominal aorta. Chondroitin sulphate C and chondroitin sulphate B fractions decreased only in the abdominal aorta and were not significantly altered in the other two segments, while heparin fraction decreased only in the thoracic aorta and was not affected in the other segments. Administration of testosterone to the orchidectomized animals counteracted these changes in the aortic GAG fractures. The enzymes concerned with the synthesis of precursors of GAG--L-glutamine:D-fructose-6-phosphate aminotransferase, UDPG dehydrogenase, and UDPG pyrophosphorylase-- all decreased in the orchidectomized animals; testosterone administration increased their activity in the orchidectomized animals. Enzymes concerned with degradation of GAG--beta-glucuronidase, beta-hexosaminidase, aryl sulphatase, cathepsin, and hyaluronidase--increased in the orchidectomized and decreased on administration of testosterone. Concentration of PAPS and activity of sulphate-activating system and sulphotransferase also decreased in the orchidectomized animals, and testosterone administration tended to restore this decrease to normal levels.     

Contents of erythorbic acid in the tissues of guinea pigs intraperitoneally administered erythorbic acid

The peripheral distribution of Sertoli cell F-actin, a cytoskeletal protein found in Sertoli cell ectoplasmic specializations, is associated with enhanced spermatid binding to the Sertoli cell and, as such, serves as a functional marker for its acquisition of binding competency. Previous studies suggest that the peripheral distribution of actin is dependent on follicle-stimulating hormone (FSH). To investigate the developmental pattern of Sertoli cell actin distribution in relation to peripubertal FSH and testosterone levels, we examined epithelial sheets from 2-8 week-old-rats. Tissues were processed for light microscopy and for the visualization of rhodamine-labeled F-actin. At 2 weeks, actin staining was diffuse throughout most of the Sertoli cells and was similar to that observed in binding-incompetent Sertoli cells. By 4 weeks, actin distribution was peripheral, acquiring the same staining pattern as observed in binding-competent Sertoli cells. Serum levels of FSH peaked at 4 weeks and declined to adult levels thereafter. Testosterone levels did not increase significantly until 6 weeks. Results show that Sertoli cell actin undergoes peripheral reorganization concurrent with the peripubertal peak of FSH but prior to the peripubertal rise of testosterone. The study demonstrates a temporal correlation between the peripubertal FSH rise and the actin redistribution in Sertoli cells that is consistent with an induction of this redistribution by FSH. These results suggest that FSH induces binding competency in Sertoli cells.     

In vivo metabolism of alpha-tocopherol in lipoproteins and liver: studies on rabbits in response to acute cholesterol loading

OBJECTIVE: To investigate the transport of alpha-tocopherol in lipoproteins of rabbits under normal diet and under acute loading of cholesterol. DESIGN: Two New Zealand White rabbits were fed 14C-alpha-tocopherol acetate in a single oral dose and the recovery of radiolabel in lipoproteins and plasma was monitored. Low density lipoprotein (LDL) from these animals was obtained and labeled with [3H] cholesteryl ester. Three other rabbits were injected with this double-labeled LDL in the native form; while three other animals received this LDL in the acetylated form. RESULTS: Plasma clearance, liver uptake and levels of radiolabel in high density lipoprotein (HDL) of animals injected with 14C[3H]acetyl LDL were significantly higher than those in animals injected with 14C[3H]native LDL. Larger particles of HDL, rich in apolipoprotein E (apoE) carried significantly higher levels of both labels in rabbits injected with acetylated LDL. CONCLUSION: These results provide evidence for in vivo mechanisms of "reverse alpha-tocopherol transport", analogous to "reverse cholesterol transport".     

Conversion of injected waste plastics in blast furnace

Operation of several blast furnaces proved that waste plastic (WP) injection makes recycling of industrial and municipal organic wastes and coke saving possible. However, the extent and reaction kinetics of plastic conversion are hardly explored yet. Therefore, a comprehensive study on WP characteristics and conversion behaviour under simulated raceway, bird's nest and shaft conditions, as well as on its interaction with coke, has been undertaken. Numerous analytical, laboratory and pilot facilities have been used. It has shown that despite favourable chemistry, it is hardly possible to reach a high conversion degree of plastics under the raceway conditions. Consumption of unburned residues in coke bed and in shaft is possible. The effect of this phenomenon on coke reactivity has to be considered as well.     

High oxygen delivery and extraction by perfluorocarbon-primed extracorporeal membrane oxygenation do not prevent anaerobic metabolism in rabbits

BACKGROUND: The development of endocrine tumours of the duodenopancreatic area (ETDP) is thought to be slow, but their natural history is not well known. The aim of this study was to determine the factors that influence survival of patients with ETDP. PATIENTS/METHODS: Eighty two patients with ETDP (44 non-functioning tumours, 23 gastrinomas, seven calcitonin-secreting tumours, four glucagonomas, three insulinomas, one somatostatinoma) followed from October 1991 to June 1997 were included in the study. The following factors were investigated: primary tumour size, hormonal clinical syndrome, liver metastases, lymph node metastases, extranodular/extrahepatic metastases, progression of liver metastases, local invasion, complete resection of the primary tumour, and degree of tumoral differentiation. The prognostic significance of these factors was investigated by uni- and multi-variate analysis. RESULTS: Twenty eight patients (34%) died within a median of 17 months (range 1-110) from diagnosis. Liver metastases (p = 0.001), lymph node metastases (p = 0.001), progression of liver metastases (p < 0.00001), lack of complete resection of the primary tumour (p = 0.001), extranodular/extrahepatic metastases (p = 0.001), local invasion (p = 0.001), primary tumour size > or = 3 cm (p = 0.001), non-functioning tumours (p = 0.02), and poor tumoral differentiation (p = 0.006) were associated with an unfavourable outcome by univariate analysis. Multivariate analysis identified only liver metastases (risk ratio (RR) = 8.3; p < 0.0001), poor tumoral cell differentiation (RR = 8.1; p = 0.0001), and lack of complete resection of the primary tumour (RR = 4.8; p = 0.0007) as independent risk factors. Five year survival rates were 40 and 100% in patients with and without liver metastases, 85 and 42% in patients with and without complete resection of primary tumour, and 17 and 71% in patients with poor and good tumour cell differentiation respectively. CONCLUSION: Liver metastases are a major prognostic factor in patients with ETDP. Progression of liver metastases is also an important factor which must be taken into account when deciding on the therapeutic approach. The only other independent prognostic factors are tumoral cell differentiation and complete resection of the primary tumour.     

Basal Stability Analysis of Braced Cuts in Clay

The evaluation of basal stability is important in the design of braced excavations in clay. Limitations exist in two common methods of analysis—Terzaghi's method and Bjerrum and Eide's—and their results vary. Two improved methods of analysis, one a direct modification of Terzaghi's and the other based on limit analysis, have been proposed. The modified Terzaghi method provides factors of safety that are close to Bejerrum and Eide's solutions. The factors of safety as obtained from limit analysis are the lowest and are consistent with field observations of classical braced cuts in clay.     

Pulsatile versus nonpulsatile flow. No difference in cerebral blood flow or metabolism during normothermic cardiopulmonary bypass in rabbits

BACKGROUND: Although pulsatile and nonpulsatile cardiopulmonary bypass (CPB) do not differentially affect cerebral blood flow (CBF) or metabolism during hypothermia, studies suggest pulsatile CPB may result in greater CBF than nonpulsatile CPB under normothermic conditions. Consequently, nonpulsatile flow may contribute to poorer neurologic outcome observed in some studies of normothermic CPB. This study compared CBF and cerebral metabolic rate for oxygen (CMRO2) between pulsatile and nonpulsatile CPB at 37 degrees C. METHODS: In experiment A, 16 anesthetized New Zealand white rabbits were randomized to one of two pulsatile CPB groups based on pump systolic ejection period (100 and 140 ms, respectively). Each animal was perfused at 37 degrees C for 30 min at each of two pulse rates (150 and 250 pulse/min, respectively). This scheme created four different arterial pressure waveforms. At the end of each perfusion period, arterial pressure waveform, arterial and cerebral venous oxygen content, CBF (microspheres), and CMRO2 (Fick) were measured. In experiment B, 22 rabbits were randomized to pulsatile (100-ms ejection period, 250 pulse/min) or nonpulsatile CPB at 37 degrees C. At 30 and 60 min of CPB, physiologic measurements were made as before. RESULTS: In experiment A, CBF and CMRO2 were independent of ejection period and pulse rate. Thus, all four waveforms were physiologically equivalent. In experiment B, CBF did not differ between pulsatile and nonpulsatile CPB (72 +/- 6 vs. 77 +/- 9 ml.100 g-1.min-1, respectively (median +/- quartile deviation)). CMRO2 did not differ between pulsatile and nonpulsatile CPB (4.7 +/- 0.5 vs. 4.1 +/- 0.6 ml O2.100 g-1.min-1, respectively) and decreased slightly (0.4 +/- 0.4 ml O2.100 g-1.min-1) between measurements. CONCLUSIONS: During CPB in rabbits at 37 degrees C, neither CBF nor CMRO2 is affected by arterial pulsation. The absence of pulsation per se is not responsible for the small decreases in CMRO2 observed during CPB.     

Regularities of interaction of zinc sulfide with the arsenate ion in sulfuric acid solutions

Regularities of interaction of zinc sulfide with the arsenate ion in a sulfuric acid medium are investigated. The rates of dissolution of zinc sulfide and precipitation of arsenic increase proportionally to an increase in the concentration of sulfuric acid. However, on attaining the critical value (～0.1 mol), they vary insignificantly. The experimental activation energies of dissolution of zinc sulfide and precipitation of arsenic are 9.7 and 16.5 kJ/mol, respectively. Based on the investigations carried out, it is concluded that the limiting stage of interaction is the diffusion of reagents and reaction products through a gas veil consisting of hydrogen sulfide bubbles that is formed on the surface of zinc sulfide particles.