Effects of chlorobenzenes and their methyl sulfone metabolites on microsomal enzymes associated with drug metabolism in rat liver

The effects of m- and o-dichlorobenzenes (DCBs), 1,2,4-trichlorobenzene (TCB) and their methylsulfonyl metabolites on the activities of hepatic microsomal reduced nicotinamide adenine dinucleotide phosphate (NADPH)-cytochrome c reductase, reduced nicotinamide adenine dinucleotide (NADH)-cytochrome b5 reductase and uridine diphosphate (UDP)-glucuronyltransferase (UDPGT) were studied. The treatment of rats with m-DCB, 1,2,4-TCB, 2,4-, 3,5- or 3,4-dichlorophenyl methyl sulfone (DCPSO2Me) or 2,4,5-trichlorophenyl methyl sulfone (TCPSO2Me) significantly increased NADPH-cytochrome c reductase activity, but o-DCB had no effect on this enzyme activity. All three chlorinated benzenes slightly reduced NADH-cytochrome b5 reductase activity, whereas the methylsulfonyl compounds elicited no change in the enzyme activity. Treatments with m- and o-DCBs, 1,2,4-TCB and 2,4,5-TCPSO2Me enhanced UDPGT activities toward both chloramphenicol (CP) and p-nitrophenol (NP). 2,4-, 3,5- and 3,4-DCPSO2Mes increased the activity of UDPGT toward CP but not toward p-NP. These findings concerning the effects of 2,4-, 3,5- and 3,4-DCPSO2Mes on the activities of NADPH-cytochrome c reductase and UDPGT support our hypothesis that the methylsulfonyl metabolites derived from m- and o-DCBs are phenobarbital-type inducers of the hepatic microsomal drug-metabolizing enzymes. It is concluded that the methyl sulfone derivatives of m- and o-DCBs and 1,2,4-TCB are inducers of phase I reactions in hepatic microsomal drug metabolism, and they have increasing effects on the phase II enzyme activities, such as UDPGT. Thus, the methyl sulfones seem to play an important role in the inducing effects of their parent compounds, m- and o-DCBs and 1,2,4-TCB, on the drug-metabolizing enzyme systems.

Mechanisms of absorption of inorganic mercury from rat small intestine. II. Composite effects of pH and halide ions on transport of mercuric chloride into isolated brush border membrane vesicles in rats

Composite effects of pH and halide ions on the transport of HgCl2 into brush border membrane vesicles (BBMV) were investigated in rats. BBMV were incubated for 10 min. in buffer solution at different pH containing 10(-4) M HgCl2. The increase in pH increased the uptake of Hg by BBMV as a result of the increase in transport of Hg into intravesicular space and decrease in binding of Hg to BBMV. The isotonic displacement of NaCl in the buffer solution by LiCl or KCl did not change the uptake of Hg at each pH. The displacement of NaCl by mannitol increased the uptake of Hg at each pH, while the displacement by NaBr or NaI decreased the uptake and diminished the increasing effect of pH on the uptake of Hg. These changes in uptake of Hg due to the displacement were mainly ascribed to the changes in transport of Hg. These results suggest that the increase in pH mainly increases the transport of HgCl2 as a result of the conversion to hydroxide forms of Hg such as Hg(OH)Cl and Hg(OH)2, and Cl- Br- and I- act as the competing ions with OH- and decrease the transport of Hg.

Myocardial depression in hyperdynamic endotoxemia

The presence of myocardial depression is difficult to assess in most animal models of septic shock caused by hypovolemia. We studied endotoxemia in fluid-resuscitated conscious sheep. They underwent chronic instrumentation with pulmonary artery, arterial, and left atrial catheters. After 1 week of recovery, 1.5 micrograms/kg of endotoxin (LPS) was administered intravenously over a period of 30 min. One group of nine sheep stayed on baseline fluids (2 ml/kg/h of Ringer's lactate), while a second group (n = 6) was resuscitated with 7 ml/kg/h Ringer's lactate solution over the 24-h study period. Both groups were compared with controls. Eight hours after LPS, left ventricular stroke work index was depressed in both groups. In the group resuscitated with 7 ml/kg Ringer's lactate this depression associated with a normal left atrial pressure and a constant peripheral resistance indicated a shift in the Starling work curve downward and to the right evidencing myocardial depression.

Long-term observations in cases with spontaneous carotid-cavernous fistulas

Twenty-six cases with spontaneous carotid-cavernous fistulas were followed up for periods ranging between 4 months and 9 years 8 months. A complete regression of symptoms without reappearance for more than 6 months was noted in 19 cases, a marked improvement in 2 cases, and a moderate regression in 3 cases. In 2 cases, symptoms have continued for 9 years 8 months and for 1 year. The regression of symptoms was usually delayed in patients less than 60 years old, in cases in which the symptoms developed slowly, and in cases with multiple draining veins. According to our observations a regression of symptoms may occur after very slight changes of haemodynamics. Compression of the cervical carotid artery for a short time or a temporary occlusion of the carotid artery by a balloon catheter should be considered as the treatment of choice in the first instance in cases with spontaneous carotid-cavernous fistulas showing relatively low pressure and low flow shunt.

Effect of preexisting inhalation injury on response to bacteremia in sheep

Inhalation injury increases the likelihood of sepsis. We tested the hypothesis that preexisting inhalation injury would diminish bacterial clearance across the pulmonary vasculature and induce greater hemodynamic response. Live Pseudomonas aeruginosa were infused centrally for one hour in three groups of awake sheep. Inh + Ps (n = 10), with a seven to 10-day-old inhalation injury; Ps-LOW (n = 8) both received 10(7) Ps/min; and Ps-HI (n = 9) received 5 x 10(7) Ps/min. for one hour. Pulmonary hypertension was more severe in Ps-HI and Inh + Ps. A hyperdynamic response with high cardiac index and low mean arterial pressure developed in Inh + Ps and Ps-HI from six to 18 hr, while Ps-LOW, only the cardiac index was elevated at six to eight hr. The Inh + Ps and Ps-LOW groups had equivalent pulmonary artery and aortic bacterial levels, while Ps-HI had levels approximately five times higher. All groups removed bacteria efficiently in the lungs. However, preexistent inhalation injury exaggerated the pulmonary and systemic hemodynamic response.

Mechanisms of absorption of inorganic mercury from rat small intestine. I. Solvent drag effect on absorption of inorganic mercury

A correlation of mercury absorption with water absorption was investigated by using the perfusion of rat small intestine with buffers containing 10(-4) M HgCl2. With a decrease in the osmolarity of the buffers or with increases in the sodium ion and urea concentrations in the buffers, absorption of water and mercury and accumulation of mercury in the intestinal tissue increased, and the increases in mercury absorption and accumulation were found to correlate with the increase in water absorption. Both the decrease in osmolarity and the increase in sodium ion concentration increased mercury accumulation in the epithelial cell after the perfusion. But these changes did not alter the mercury distribution in subcellular fractions. The results suggest that the increase in water absorption due to the hyptonicity or the increase in concentration of sodium ion or urea increases the mercury absorption and accumulation in the epithelial cell without change in the distributional pattern of mercury in the cell.

Cardiopulmonary changes with intermittent endotoxin administration in sheep

Chronic sepsis was induced by administering endotoxin (lipopolysaccharide--LPS) at 12-hr intervals to sheep. The animals (n = 7) responded to the first dose of LPS with increased pulmonary arterial pressure (PAP), systemic vascular resistance, plasma and lymph thromboxane B2 (TxB2) concentrations, and lung lymph flow rate concurrent with a reduction in the cardiac index (CI). Subsequent doses of LPS produced an elevation of PAP and TxB2 which was progressively attenuated and eventually disappeared. With LPS the lung lymph flow was markedly elevated and CI increased. This latter was transient and associated with a reduction in systemic vascular resistance. Concomitant with the cardiopulmonary changes prekallikrein levels were not diminished, but there was a statistically significant reduction in C1-esterase inhibitor. The administration of LPS was discontinued after 5 days and the cardiopulmonary variables rapidly returned to baseline levels. Chronic endotoxemia appears to be associated with an elevated pulmonary microvascular permeability and a tendency toward a hyperdynamic circulation but with an appreciable degree of refractoriness associated with regional hemodynamics and eicosanoid biosynthesis.

Cardiopulmonary responses to continuous administration of endotoxin

The cardiopulmonary response to continuous administration of lipopolysaccharide (LPS) was studied in chronically instrumented sheep. LPS was administered in doses of 0 (sham), 6, 9, 12, and 24 ng.kg-1.h-1 for 24 h. No significant changes in the measured variables occurred in the sham group and in the 6 ng.kg-1.h-1-LPS group. With 9, 12, and 24 ng.kg-1.h-1-LPS, cardiac index rose and peripheral resistance fell to the same extent in all three groups. Lung lymph flow (QL) increased with increasing concentration of LPS. These elevations in QL occurred in the presence of only minor increases in the pulmonary artery pressure, which rose to the same extent in the 9, 12, and 24 ng.kg-1.h-1 groups. Consequently, the changes in QL were attributable to changes in fluid conductance of the pulmonary microvasculature rather than variations in hydrostatic pressure. The increase in QL correlated with a decrease in prekallikrein levels (r = 0.97), indicating that the changes in fluid conductance might have been kinin mediated.

Dysplasia of subcommissural organ in congenital hydrocephalus spontaneously occurring in CWS/Idr rats

The subcommissural organ (SCO) of the congenital hydrocephalus spontaneously occurring in CWS/Idr rats was severely reduced in size and displaced at some distance from the anterior end of the cerebral aqueduct. The cerebral aqueduct of the hydrocephalic rats was open throughout its total length during postnatal days 1-20, though it was somewhat narrower at its middle region than in the normal brain.

Increasing duration of smoke exposure induces more severe lung injury in sheep

Eighteen sheep previously prepared for chronic study were divided into three groups of six animals each. These were given graded inhalation injury utilizing smoke obtained from burning cotton-toweling material. Smoke was insufflated into animals with a modified bee smoker at temperatures less than 40 degrees C. Group H, which received 64 breaths of smoke, showed the most pronounced changes in pulmonary function. The changes consisted mainly of a profound increase in lung lymph flow following a reduced P/F ratio (PO2 in arterial blood/inspired O2 fraction) and an elevation in both thermal and gravimetrically measured extravascular lung water. Similar changes were seen in group M (48 breaths of smoke) and group L (32 breaths of smoke). However, the injury was graded based on the changes in gravimetrically measured lung water and lung lymph flow. These were highest in group H and lowest in group L. These studies confirm our ability to accurately quantitate the injury induced by smoke inhalation. In addition, it demonstrates that lung injury associated with the inhalation of smoke can be graded depending on the duration of exposure.

Ibuprofen reduces the lung lymph flow changes associated with inhalation injury

Inhalation injury was produced in sheep which were chronically prepared for study. The injury was induced by insufflating them with smoke from burning cotton cloth. One group of animals was treated with the cyclooxygenase inhibitor ibuprofen and another group was untreated. Eight hr following the administration of smoke, there was an elevation of lung lymph flow in both groups. These changes were not as severe in the animals which were treated with ibuprofen. The pulmonary changes which occur following smoke inhalation injury are associated with elevations of the metabolites of arachidonic acid, especially those generated by the cyclooxygenase pathway. These metabolites in some way contribute to the pathophysiological changes induced by the inhalation of smoke, since they are reduced by the administration of a cyclooxygenase inhibitor.

Pulmonary microvascular changes following fluid resuscitation in an ovine model of endotoxemia

Fluid resuscitation is complicated in hypotensive septic patients by their susceptibility to pulmonary edema. This problem was evaluated in the ovine model of endotoxemia with a chronic lung lymph fistula. Escherichia coli endotoxin (lipopolysaccharide, 1.5 micrograms/kg) was given intravenously over 30 minutes. Group M (n = 9) continued to receive baseline fluids (2 mL/kg/h), while group R (n = 6) received 7 mL/kg/h of Ringer's lactate. After an initial drop in cardiac index, animals in both groups developed a hyperdynamic state. The fall in mean arterial pressure seen in group M was absent from group R. The higher fluid volume resulted in a rise in left atrial pressure and pulmonary microvascular pressure. The lung lymph flow and permeability index were elevated in both groups but were higher in group R. The calculated filtration coefficient showed a threefold increase in both groups. Augmented fluid resuscitation during endotoxemia resulted in an elevated interstitial fluid flux and permeability index secondary to an increase in pulmonary microvascular pressure and greater surface area of the injured microvascular beds being perfused.

Bioethics as a prescription for civic action: the Japanese interpretation

This paper reports on recent developments in the rise of bioethics in Japan. Much of the recent interest in bioethics in Japan is seen as a response to various civic movements. The women's liberation movement, access to equal opportunity, and the recognition of patients' rights and the importance of informed consent are among some of the movements influencing the development of bioethics in Japan. The author argues that this movement is to be encouraged and fostered by health care professionals, public policy makers, as well as lay persons in Japan.

Absence of subcommissural organ in the cerebral aqueduct of congenital hydrocephalus spontaneously occurring in MT/HokIdr mice

The midbrains of pups with congenital hydrocephalus spontaneously occurring in MT/HokIdr mice were histologically examined. The subcommissural organ (SCO) and the posterior commissure were completely absent in the hydrocephalic brain. The cerebral aqueduct in the hydrocephalic brain was never completely stenosed, though it was somewhat narrowed in its middle region as compared with that in the normal brain. A possible interrelationship between an absence of SCO and a cause of congenital hydrocephalus is discussed.