Effects of ethanol and hepatic vitamin A on the proliferation of lipocytes in regenerating rat liver

The effects of ethanol and hepatic vitamin A on lipocyte proliferation were studied in regenerating rat livers. Positive identification of proliferating lipocytes was achieved by a double immunostaining sequence for cytoplasmic desmin and bromodeoxyuridine-labelled nuclei. Ethanol administration caused a 76 and 36% reduction in labelling indices of lipocytes 2 and 3 days after hepatectomy, respectively, thereby delaying the onset of the proliferative peak of lipocytes by 1 day compared to the control. Hepatic vitamin A did not decrease until 4 days after hepatectomy. The relationship between hepatic vitamin A and lipocyte proliferation was further evaluated in rats fed diets containing four different amounts of vitamin A. Despite the striking differences in liver vitamin A levels, the proliferative activity of lipocytes was unaffected, as measured at the peak of lipocyte proliferation 2 days after hepatectomy. These data indicate that ethanol ingestion suppresses the proliferative response of lipocytes to partial hepatectomy but that this ethanol effect is independent of changes of vitamin A levels in the liver.

Relationship between apo[a] isoforms and Lp[a] density in subjects with different apo[a] phenotype: a study before and after a fatty meal

Plasma Lp[a] levels and apo[a] isoform distribution among lipoproteins isolated by density gradient ultracentrifugation were studied in subjects with one-band or two-band apo[a] phenotypes as assessed by gradient gel electrophoresis before and after an oral fat load. There were no significant differences in the ultracentrifugal profile between fasting plasma and postprandial plasma that was freed of triglyceride-rich particles (TRP). One-band phenotypes exhibited a single symmetrical peak in the density gradient, whereas two-band phenotypes exhibited a multi-modal distribution. Low molecular weight apo[a] isoforms were preferentially associated with low density Lp[a] whereas high molecular weight apo[a] isoforms were found with high density Lp[a] particles. Feeding a high fat meal caused no significant increase in the total plasma level of Lp[a]. However, the isolated TRP contained the apoB-100-apo[a] complex in a quantity that represented only about 1% of its total amount in the fasting plasma. In all cases the apo[a] isoforms present in TRP were also present in the fasting plasma; however, in the two-band apo[a] phenotypes the ratio of the slow over the fast migrating band was in all cases about eightfold higher in TRP than in the fasting plasma. These observations indicate that postprandially a small percentage of apoB-100-apo[a] associates with TRP and suggest that this complex may derive from de novo synthesis rather than from a pre-existing Lp[a] plasma pool. The liver would be the source of the complex due to the presence in the latter of apoB-100.

Outbreak of neonatal listeriosis associated with mineral oil

In June, 1989, an outbreak of nosocomial listeriosis occurred in Costa Rica. Listeria monocytogenes was isolated from 9 ill infants 4 to 8 days old who were born after the delivery of an infant with early onset listeriosis. One nosocomial infection was fatal, 2 required mechanical ventilation and 1 resulted in hemiparesis. A higher proportion of cases than other infants born during the outbreak were delivered by cesarean section (55% vs. 24%, P = 0.04). Compared with the mothers of 36 random controls, case mothers were more often primiparous (odds ratio, 6.2, P = 0.03) or received general anesthesia before delivery (odds ratio, 4.4, P = 0.09). All infants were bathed with mineral oil from a multidose container. Culture of the oil by cold enrichment grew L. monocytogenes 4b with the same electrophoretic enzyme type as the outbreak strain. We hypothesize that aspiration of contaminated oil may have resulted in systemic listeriosis. General anesthesia may have increased the risk of aspiration. Lung tissue from the infant who died showed lipid-laden macrophages consistent with oil aspiration and had evidence of L. monocytogenes DNA detected by polymerase chain reaction. This is the first nosocomial outbreak of listeriosis in which a common source suggested epidemiologically was microbiologically confirmed. The high attack rate (greater than 200 times the United States rate of perinatal listeriosis) emphasizes the susceptibility of healthy neonates to L. monocytogenes. The results of our study led to the discontinuation of the use of mineral oil for bathing neonates in Costa Rica.

Spontaneous saccular cerebral aneurysm in a rat

A saccular cerebral aneurysm was incidentally found at the bifurcation of a fenestrated anterior cerebral artery of 35-week-old Sprague-Dawley rat. The animal had been fed a normal laboratory diet. The internal lamina extended for a short distance into the neck of the aneurysm and then suddenly disappeared. The medial layer ended abruptly at the neck of the aneurysm. The aneurysmal wall consisted mainly of connective tissue, and of some poorly stained fragments of elastic lamina. No evidence of polyarteritis nodosa or any other inflammatory reaction was obtained. These findings were the same as those observed in man. Therefore, this aneurysm proved to be of truly spontaneous origin. In contrast to experimental aneurysms in rats and in monkeys, in which aneurysms are observed very often, degenerative changes of the elastic lamina in spontaneous aneurysm in the rat were confined to the neck of the aneurysm. This fact may explain partly the difference in frequency between spontaneous and experimental aneurysms in animals. The present study indicates that degenerative changes of the elastic lamina play a very important role in the development of saccular cerebral aneurysms.

Angiographic study of induced cerebral aneurysms in primates

Five cynomolgus monkeys treated with unilateral carotid ligation, renal hypertension, and beta-aminopropionitrile feeding were studied repeatedly by cerebral angiography to clarify the growth process of saccular cerebral aneurysms. Repeated angiography demonstrated saccular cerebral aneurysms in three of five monkeys; two aneurysms were found 15 months and a third 12 months after the operation. At autopsy, one saccular aneurysm was found to be bilocular in shape, and the others were unilocular. Fusiform aneurysms were also observed in four monkeys. Microscopic studies revealed the walls of the saccular aneurysms were very thin and consisted of fibrous tissue. In one aneurysm, the aneurysmal sac was almost obstructed by a well-organized thrombus. No evidence of intramural hemorrhage was found in any of the saccular cerebral aneurysms. The conversion of early aneurysmal changes into saccular aneurysms was found to occur abruptly, and no consistent growth rate was noted. The multiloculation of saccular aneurysms was closely related to the size of an aneurysm. The present study indicates that a saccular cerebral aneurysm may grow abruptly from one of several different kinds of early aneurysmal changes.

Effect of ethanol on brain catecholamines in rat lines developed for differential ethanol-induced motor impairment

The importance of the central catecholamines, with the emphasis on the noradrenergic neurons in the differential sensitivity to ethanol between the AT (alcohol-tolerant) rats selected for low and the ANT (alcohol-nontolerant) rats selected for high sensitivity to ethanol-induced (2 g/kg) motor impairment, was clarified by studying the effects of ethanol (2 and 4 g/kg, IP) on the utilization of norepinephrine (NA) and dopamine (DA), and on the metabolism of NA. The utilization of the catecholamines was estimated from the disappearance of the amines after inhibition of the brain tyrosine hydroxylase by alpha-methyl-p-tyrosine (200 mg/kg, IP), given 15 min after the administration of ethanol. The formation of 3-methoxy-4-hydroxy-phenylglycol (MHPG) was used as an estimate of NA metabolism, and was measured 30 min after the administration of ethanol. The basal utilization rate of NA and DA was similar between the two rat lines, but the increased formation of MHPG suggested that the naive AT rats had a higher noradrenergic activity in the limbic forebrain, hypothalamus, and cerebellum than did ANT rats. In the brain of both lines, ethanol accelerated the utilization and metabolism of NA in the same manner. Ethanol also increased the utilization of DA in the limbic forebrain of the AT and ANT rats. The higher sensitivity of the ANT rats' DA neurons to ethanol in the limbic forebrain and striatum was revealed by the significant rat line X ethanol interaction. The present findings suggest that the AT and ANT rats differ in the dopaminergic, but not in the noradrenergic responses to ethanol.

Restriction fragment length polymorphisms among uropathogenic Escherichia coli isolates: pap-related sequences compared with rrn operons

Among the adhesin-encoding virulence operons associated with uropathogenic Escherichia coli, only pap (pyelonephritis-associated pilus)-related gene clusters typically exhibit variation in their structure and chromosomal copy number. To access further such variability, we compared pap restriction fragment length polymorphisms (RFLPs) with those detected among rRNA (rrn) operons, which encode an essential host function unrelated to virulence. To place such findings in a phylogenetic perspective, the E. coli isolates were also characterized by using multilocus enzyme electrophoresis. Variation in the rrn RFLP profiles correlated with evolutionary divergence resolved by multilocus enzyme electrophoresis; isolates with identical rrn profiles represented the same or closely related electrophoretic types. In contrast, such isolates frequently had different pap-related RFLPs, indicating that these genetic variations have developed recently relative to the changes associated with essential rrn operons or metabolic enzymes. Despite such fluctuations, two lines of evidence indicate conditions under which the pap-related RFLPs can be stably maintained. First, for each of 20 patients with urosepsis, both the primary urinary tract isolate and the concurrent blood isolate were identical. Second, although obtained from different patients, some isolates representing the same electrophoretic type also had identical pap-related RFLPs. Thus, the genotypic diversity of this virulence adhesin operon was not generated during the course of acute infection or during laboratory manipulations. Since fecal E. coli isolates frequently carry chromosomally encoded pap-related gene clusters, these findings suggest that the intra- and interchromosomal recombination events generating the polymorphisms associated with the pap-related sequences likely occur among the E. coli of the commensal reservoir.

Resolution of recent evolutionary divergence among Escherichia coli from related lineages: the application of pulsed field electrophoresis to molecular epidemiology

Escherichia coli infecting the urinary tract and other extraintestinal sites are often identical in many phenotypic and genotypic characteristics. To discriminate among pathogenic E. coli isolates, chromosomal DNA was digested with restriction endonucleases that recognize eight base pair sequences and the resulting 20-25 fragments were resolved by pulsed field gel electrophoresis (PFGE). Different restriction fragment profiles were detected for isolates obtained from different patients, including isolates of the same evolutionary lineage that were identical in electrophoretic type, serotype, and antibiotic sensitivities. In contrast, isolates obtained from separate sites of infection within the same patient had identical restriction profiles. These results indicate that PFGE can resolve recent evolutionary divergence within E.coli lineages and, consequently, offers a powerful new means for precisely performing molecular epidemiology. In addition, these studies provide genetic evidence that E. coli urinary tract infection within a given patient is typically due to the expansion of a single bacterial clone.

Measurement of methionine enkephalin and leucine enkephalin in rat brain regions by high-performance liquid chromatography with coulometric electrochemical detection

A method is described for the determination of two pentapeptides, methionine enkephalin (H-Tyr-Gly-Gly-Phe-Met-OH) (ME) and leucine enkephalin (H-Tyr-Gly-Gly-Phe-Leu-OH) (LE) in discrete rat brain regions. Separation and quantitation were performed by reversed-phase high-performance liquid chromatography with coulometric detection. Perchloric acid extracts of the tissue after enzyme inactivation by heat treatment were passed through a normal-phase solid-phase extraction diol (COHCOH) column, and endogenous ME and LE were subsequently eluted with methanol. The mobile phase was 1-propanol-phosphate buffer (pH 5.5) (9:91). Eluted samples were detected electrochemically using dual coulometric electrodes operated in screen mode. Each of these enkephalins gave a linear response over the range 40-160 ng/ml cerebellar homogenate (0.8-3.2 ng absolute amount on column). Analytical recoveries of synthetic ME and LE, added to the homogenates, were 70 +/- 3 and 70 +/- 10%, respectively, when compared with enkephalins dissolved in water. The mean between-assay coefficients of variation for synthetic ME and LE were lower than 10.7 and 7.4%, respectively, over the concentration range studied. The within-assay coefficients of variation for synthetic ME and LE were 11.4 and 9.5%, respectively, at the lowest concentration. The present method has been applied to a study determining the levels of endogenous ME and LE in discrete rat brain regions.

Establishment of the experimental conditions for inducing saccular cerebral aneurysms in primates with special reference to hypertension

To find out the optimum experimental conditions for the induction of saccular cerebral aneurysms in primates, various procedures for inducing renal hypertension were used in cynomolgus monkeys treated with ligation of unilateral carotid artery and beta-amino-propionitrile feeding. Animals were divided into four groups. In the first group, both kidneys were simultaneously compressed with a figure-eight ligation. In the second group, the kidneys were ligated at an interval of one week. In the third and fourth groups, posterior branches of both renal arteries were ligated at the same time, or at an interval of one week, respectively. Hypertension about 200 mmHg was produced only in the last group and aneurysms were noted in more than half of these hypertensive animals. The best procedure for renal hypertension to induce cerebral aneurysms was proved to be ligation of the posterior branches of both renal arteries at an interval of one week. We can conclude that lasting severe hypertension is essential for inducing cerebral aneurysms in monkeys.

Histopathological study of induced cerebral aneurysms in primates

Experimental cerebral aneurysms in monkeys induced by treating them with unilateral carotid ligation, renal hypertension, and beta-aminopropionitrile feeding were studied macroscopically and with light microscopy. Macroscopically, 13 cerebral aneurysms were observed in six of seven monkeys. Microscopically, the elastic lamina and the media ended around the beginning of the aneurysms. The thin aneurysmal walls consisted of fibrous connective tissues. All findings were generally in accordance with spontaneous lesions in humans. The induced cerebral aneurysms in primates are thought to be a suitable experimental model to clarify the pathogenesis of the disease.

Characterization of natural and total artificial heart acceleration

The pulsatile nature of an implanted total artificial heart (TAH) may have several deleterious effects. To define the level of TAH impact, acceleration was measured and compared with that of the natural heart in a series of in vivo and in vitro experiments. In TAH implantations in calves, miniature accelerometers were incorporated onto the housing of a Utah-100 left ventricle. Identical accelerometers were glued to felt pledgets to obtain measurement of radial cardiac acceleration when sewn to the epicardial surface of the natural heart. Measurement of natural and artificial heart acceleration was made both intraoperatively and postoperatively in several animals. Many pumping conditions were also investigated with a similarly instrumented UVAD 85 left ventricle during in vitro testing. The peak natural heart acceleration measured was nearly 2 g both intraoperatively and at rest. Treadmill exercise or epinephrine infusion produced twice the resting peak acceleration value of the natural heart. Artificial heart peak acceleration as great as +/- 100 g was found intraoperatively and postoperatively. Peak TAH acceleration could be reduced by allowing the ventricle to fill fully prior to the start of the next systole, by allowing the ventricle to fully eject prior to the next diastole, or by using a ventricular pressurization waveform that has a smooth contour with a sinusoidal-like profile. The ability to lower TAH acceleration may lead to a reduction in undesirable consequences of TAH implantation.

Molecular epidemiology of adhesin and hemolysin virulence factors among uropathogenic Escherichia coli

The pap, prs, pil, and hly operons of the pyelonephritic Escherichia coli isolate J96 code for the expression of P, F, and type 1 adhesins and the production of hemolysin, respectively; the afaI operon of the pyelonephritic E. coli KS52 encodes an X adhesin. Using different segments of these operons as probes, colony hybridizations were performed on 97 E. coli urinary tract and 40 fecal clinical isolates to determine (i) the presence in the infecting bacteria of nucleotide sequences related to virulence operons, and (ii) the phenotypic properties associated with such sequences. Coexpression of P and F adhesins encoded by pap-related sequences was detected more frequently among isolates from patients with pyelonephritis (32 of 49, 65%) than among those with cystitis (11 of 48, 23%; P less than 0.0001) or from fecal specimens (6 of 40, 15%; P less than 0.0001). Therefore, the expression of both adhesins appears to be critical in the colonization of the upper urinary tract. In contrast, afaI-related sequences were detected significantly more frequently among isolates from patients with cystitis, suggesting that this class of X adhesin may have a role in lower urinary tract infections. Urinary tract isolates differed from fecal isolates by a low incidence of type 1 adhesin expression among pil probe-positive isolates. hly-related sequences were only detected in pap probe-positive isolates. The frequency of hemolysin production among pap probe-positive isolates was not associated with a particular pattern of infection. The distribution of these virulence factors was similar in the presence or absence of reflux, indicating that structural abnormalities of the urinary tract did not facilitate colonization by adhesin-negative isolates.

Structure and copy number of gene clusters related to the pap P-adhesin operon of uropathogenic Escherichia coli

The structurally related pap and prs operons of the uropathogenic Escherichia coli isolate J96 encode a P and an F adhesin that mediate bacterial attachment to the human P blood group antigen and the Forssman antigen, respectively. Using probes prepared from different segments of the pap operon, Southern blot hybridizations were performed to characterize pap-related sequences of 30 E. coli clinical isolates expressing different adhesin phenotypes. Gene clusters encoding P and F adhesins displayed no restriction site polymorphism in sequences homologous to the papH, papC, and papD genes that encode proteins essential to the transport and polymerization of the subunits of the P-pilus adhesin. In contrast, pap-related genetic elements associated with a null phenotype either lacked homology to the papH, papC, and papD genes or displayed a restriction site polymorphism in this region. Sequences within and surrounding the J96 papG and prsG adhesin genes that determine the binding specificities to the P and F antigens, respectively, were not conserved. However, gene clusters encoding different binding specificities could not be distinguished based on such restriction site polymorphisms. The majority of clinical isolates had more than one copy of pap-related sequences that involved gene clusters similar to the J96 pap operon, as well as genetic elements that were related only to a part of this operon. The implications of this unexpected copy number polymorphism with respect to possible recombination events involving pap-related sequences are discussed.

Burn injury to trunk of rat causes denervation-like responses in the gastrocnemius muscle

Thermal injury results in dystropic changes in skeletal muscle and abnormal pharmacological responses to neuromuscular relaxants, each of which suggests a denervation-like phenomenon. In the rat thermal injury model we examined whether, as in denervation states, increases in nicotinic acetylcholine receptors (AChR) and hyposensitivity to d-tubocurarine (dTc) are found. While anesthetized, thermal injury was imposed to trunk only. At 10, 14, and 21 days after injury the effective doses of dTc for left gastrocnemius tension suppression to 95% of control tension (ED95) were 0.213 +/- 0.039, 0.305 +/- 0.070, and 0.214 +/- 0.032 mg/kg, respectively. These values were significantly higher (P less than 0.05) than control values (0.155 +/- 0.006 mg/kg). The AChR concentrations in the left gastrocnemius, quantitated by 125I-alpha-bungarotoxin binding, increased at 10, 14, and 21 days to 182 +/- 20% (P less than 0.001), 166 +/- 22% (P less than 0.03), and 164 +/- 18% (P less than 0.001) of control, respectively. AChR concentrations in the right gastrocnemius also increased subsequent to thermal injury. Changes in effective dose of dTc for 50 and 95% twitch suppression in the left gastrocnemius correlated significantly with changes in AChR concentrations for the same muscle (r = 0.73 and 0.81, P less than 0.001, respectively). This study confirms the hypothesis that the systemic effects of thermal injury include an increase in AChR at sites distant from thermal injury, which may account for the skeletal muscle dysfunction and aberrant responses to neuromuscular relaxants.

Involvement of internal elastic lamina in development of induced cerebral aneurysms in rats

To elucidate the role of the internal elastic lamina in the development of cerebral aneurysm, the bifurcation of the anterior cerebral artery and olfactory artery was histologically studied in control and experimental rats treated with unilateral carotid ligation and renal hypertension. Various stages of aneurysm formation were compared, and it was found that early aneurysmal changes were always present just distal to the apical intimal pad on the anterior cerebral artery side. The internal elastic lamina was thinned and fragmented just distal to the pad even in the very early stage of aneurysm formation when the medial layer was still present. In control rats, the internal elastic lamina had a tendency to thin and fragment at the site where aneurysms would develop in experimental rats. Our study shows that changes of the internal elastic lamina were present just distal to the pad even in control rats, which never develop cerebral aneurysms. Under hemodynamic stress augmented by experimental treatments, further degenerative changes of the internal elastic lamina and involvement of the medial layer are considered to occur and result in aneurysm formation there.

Burn injury to rat increases nicotinic acetylcholine receptors in the diaphragm

Thermal injury induces aberrant responses to neuromuscular (NM) blocking drugs, and it has been speculated that an increase in nicotinic acetylcholine receptors (AchR) may contribute to the altered response. Using the diaphragmatic muscle as a representative of skeletal muscle, the changes in AchR were examined. The diaphragm, rather than limb muscles, was chosen to avoid the effects of wound contracture-induced immobilization and denervation of limb, which can also increase AchR in skeletal muscle. Study of changes in diaphragm also tested the hypothesis that increase in AchR are the result of a generalized systemic effect, and not limited to area of burn. Following a 45-55% body surface area thermal injury to the trunk (not limbs) of rats, AchR changes in the diaphragm were studied at 10, 14, 21, and 28 days after injury and compared to uninjured (control) rats. The AchR changes in the diaphragmatic muscle was assayed using 125I-alpha-bungarotoxin as the specific ligand. At 10, 14, and 21 days after thermal injury, the animals had an arrest in weight growth and the AchR concentration was increased to (mean +/- SE) 155 +/- 15% (P less than 0.02), 160 +/- 16% (P less than 0.003), and 141 +/- 16% (0.05 less than P less than 0.1), respectively, compared to control. At 28 days, probably because of wound healing and burn wound contracture, the size of thermally injured area was significantly (P less than 0.001) reduced to 19 +/- 4% of body surface area, and weight increased (P less than 0.001) compared to preburn weight.(ABSTRACT TRUNCATED AT 250 WORDS)

Experimental induction of cerebral aneurysms in monkeys

Saccular cerebral aneurysms were successfully induced in two monkeys treated with ligation of the common carotid artery, experimental hypertension, and beta-aminopropionitrile feeding. The cerebral aneurysms developed on the large arteries at the base of the brain, such as the anterior communicating artery and the internal carotid artery at the origin of the posterior communicating artery. Because of the similarity of the monkey to man as a species, the present results strongly suggest the significance of postnatal aggravating factors in the development of cerebral aneurysms in man.

Distribution of uranium in human lungs

Several human lung samples were dissected into lobes and uranium and silicon contents in each lobe were determined by the fission track method and the inductively coupled plasma-atomic emission spectrometry (ICP-AES), respectively. It was found that both uranium and silicon concentrations were high in the upper lobe compared with those in the lower one. Though the tendency may be mainly interpreted by the deposition way of airborne dust in the lung, the higher U/Si concentration ratio in the upper part than that in the lower part of lungs may suggest the partial removal of uranium deposited in the lower part of the tissue.

Duodenal neoplasms: role of CT

In a retrospective study of 14 cases of duodenal neoplasms evaluated by computed tomography (CT), there were four primary adenocarcinomas of the duodenum, one lymphoma, five metastatic carcinomas, two duodenal lipomas, one villous adenoma, and one leiomyoma. The CT findings were diagnostic in patients with duodenal lipomas. In 11 cases, a primary origin of the mass was clearly identifiable in the duodenum. Thickening of the bowel wall, tumor necrosis, ulceration, and intraluminal defects were common. The relationship of the masses to adjacent structures was clearly shown on CT scans. Extraluminal extent of the lesion was noted on CT scans in seven patients; however, at surgery only four of six were found to have extramural disease. The presence of adenopathy, liver metastases, and vascular and mesenteric invasion were also demonstrated on CT scans. Twelve patients underwent upper gastrointestinal tract series. A duodenal abnormality was seen in all 12 patients, but the extramural extent and distant metastatic involvement could not be seen on these examinations. CT scans allowed the accurate staging of eight of ten malignant lesions and thus helped in the management of duodenal tumors.

Rapid and sensitive method for measuring norepinephrine, dopamine, 5-hydroxytryptamine and their major metabolites in rat brain by high-performance liquid chromatography. Differential effect of probenecid, haloperidol and yohimbine on the concentrations of biogenic amines and metabolites in various regions of rat brain

A rapid and sensitive method has been developed for the simultaneous determination of norepinephrine, dopamine, 5-hydroxytryptamine and their respectively metabolites 3-methoxy-4-hydroxyphenylglycol, homovanillic acid, 3,4-dihydroxyphenylacetic acid, and 5-hydroxyindoleacetic acid in discrete brain regions of rats. The supernatants of tissue homogenates were injected directly into a reversed-phase liquid chromatography system, coupled with electrochemical detection. Each of these compounds gave a linear response over the range 5.5-200 ng/ml cerebellar homogenate (0.11-4.0 ng on column). Analytical recoveries of these compounds, added to the homogenate, were essentially complete when compared with standards dissolved in perchloric acid. The average between-assay coefficients of variation for all these compounds were lower than 6.9% over the range 5.5-200 ng/ml. The within-assay coefficients of variation were lower than 9.7%, measured at 5.5 or 23.6 ng/ml. With the present test parameters and mobile phase conditions, all compounds were readily oxidized at 0.8 V vs. a Ag/AgCl reference electrode. The method was applied to an analysis of the differential activity of biogenic amines in the rat striatum, hypothalamus, and hippocampus, produced by probenecid, haloperidol and yohimbine.

Tolerance to hyperthermia produced by morphine in rat

The present study addressed the prevailing notion that the rat develops tolerance only to the hypothermic effect of morphine and not to its hyperthermic effect. Rectal temperatures were measured at different intervals after various test doses of morphine in rats that had been rendered tolerant to morphine antinociception, by daily intraperitoneal injections of 0, 20, or 200 mg/kg morphine, and dependent, as seen by naloxone-produced loss of body weight. The well-known tolerance to the hypothermic effect was confirmed by changes in the dose-response curves for latency to peak hyperthermic response. In the falling arm of the test dose time/effect curve, consistent, clear decreases in morphine hyperthermia were seen. These decreases were proportional to the chronic treatment dose, and occurred in a normal test environment, where acute hypothermic effects were produced by morphine at short test intervals, and in a warm test environment, where no hypothermia was seen. Similar effects were noted when the data were analyzed in terms of area under the time/effect curve for hyperthermia. In the morphine-treated animals, decreased hyperthermia was seen despite serum morphine levels at the time of testing being up to twice as high as those in control rats. It was concluded that substantial tolerance develops to hyperthermia produced by opiates in rats. The previous difficulty in seeing this effect is discussed in regard to the probability that, in naive rats, the effect of morphine shortly after administration of a test dose reflects a summation of two opposing, acute thermic effects. The findings challenge the view that tolerance develops only to the depressant, and not to the excitatory, effects of opiates.

Intoxicating effects of lorazepam and barbital in rat lines selected for differential sensitivity to ethanol

The motor impairing effects and plasma concentrations of barbital and lorazepam were studied in the alcohol tolerant (AT) and alcohol non-tolerant (ANT) rat lines developed for low and high sensitivity to motor impairment from ethanol. The mixed (M) line, from which the AT and ANT rats were derived, was also included in the study. Like ethanol, barbital and lorazepam impaired the performance of the ANT rats more than that of the AT rats. The motor performance of the M rats was relatively more impaired after barbital than after lorazepam administration at the same dose used in the AT and ANT rats. At the two latter time points (2.5 and 3.5 h) the sensitive ANT rats had significantly higher serum barbital concentrations than the AT rats. The serum barbital concentrations of the AT and ANT rats did not differ, however, at the two first time points (0.5 and 1.5 h) of the tilting plane tests, although the ANT rats were significantly more intoxicated. The concentrations of lorazepam in plasma do not explain the differential motor impairment either, since the sensitive ANT rats had lower plasma concentrations than the insensitive AT rats. The results, thus, suggest that the selection involved in the development of the AT and ANT lines has not been specific for ethanol. The results also support the idea that ethanol, barbiturates and benzodiazepines have some modes of action in common.

Simultaneous determination of biogenic amines and morphine in discrete rat brain regions by high-performance liquid chromatography with electrochemical detection

A simple and sensitive method has been developed for the simultaneous determination of norepinephrine, epinephrine, dopamine, 5-hydroxytryptamine, 5-hydroxyindoleacetic acid, and morphine in discrete rat brain regions by reversed-phase high-performance liquid chromatography with electrochemical detection. Perchloric acid extracts of the tissue were directly injected into the chromatographic system. Each of these compounds gave a linear response over the range of 20-160 ng/ml cerebellar homogenate (0.4-3.2 ng on column). Recoveries of these compounds, added to the homogenates, were complete when compared with standards dissolved in perchloric acid. The average between-run coefficients of variation for all these compounds were lower than 7.4% over the range of 20-160 ng/ml, and the within-run coefficients of variation at 20 ng/ml were lower than 8.7%. The present method has been applied to a study of the effects of intraperitoneal administration of morphine on biogenic amines in several discrete rat brain regions.

Increased vitamin A in esophagus and other extrahepatic tissues after chronic ethanol consumption in the rat

In rats fed ethanol (36% of total energy) for 1 month, vitamin A content of the esophageal mucosa was found to be increased 5-fold, compared to animals pair-fed an isocaloric control diet containing the same amount of vitamin A. Similar results were observed with diets of either lower vitamin A content or zinc supplementation. Significant increases of retinoids were also found in lungs, trachea, kidneys, and testes, but not in the eyes. These increases in extrahepatic tissues contrasted strikingly with the concomitant decrease in the liver and suggests that chronic ethanol consumption may be associated with some mobilization of vitamin A from the liver to other organs.

Early changes of experimentally induced cerebral aneurysms in rats: scanning electron microscopic study

To obtain information about the early changes of experimentally induced cerebral aneurysms in rats, the luminal surface of branching areas of their cerebral arteries was examined with a scanning electron microscope. At the branching sites of major cerebral arteries in the control animals, the intima just distal to the apex markedly protruded into the lumen forming a linear bank-like intimal pad. Along and distal to this pad, there was a shallow long groove (juxta-apical groove). Such grooves were much deeper and wider in experimental animals than those in the control rats. By studying various stages of early aneurysmal changes, cerebral aneurysms were proven to develop from such grooves. In deep juxta-apical grooves and small aneurysms, round regenerated endothelial cells with a large number of microvilli were diffusely present. Degenerated cells with balloons and craters were observed intermingled with such regenerated cells. Interendothelial gaps were also seen. The present study showed the complex structure of the apex of arterial bifurcation in rats, including bank-like intimal pads. Such complex structures of the branching sites were considered to be responsible for the initiation of cerebral aneurysms due to endothelial injury possibly caused by turbulent flow there.

Early changes of experimentally induced cerebral aneurysms in rats. Light-microscopic study

The changes of the anterior cerebral artery/olfactory artery junction, one of the favorite sites of aneurysm formation, in rats treated with unilateral ligation of the common carotid artery and renal hypertension were investigated by light microscopy. The initial changes of aneurysm occurred not at the apex itself, but on the distal side of the major branch adjacent to the apex, at the intimal pad and the neighboring distal portion. Here the internal elastic lamina showed various degenerative changes and disappearance. The neighboring distal portion adjacent to the intimal pad showed a shallow depression associated with a thinning of the media due to a decrease of medial smooth muscle cells in number even in some control animals. Such degenerative changes of the internal elastic lamina and medial smooth muscle cells caused by hemodynamic stress due to branching structure, including intimal pads, augmented by the experimental treatment, are supposed to be the basis for aneurysm formation.

Studies on avian erythrocyte metabolism. XIV. Effect of CO2 and pH on P50 in the chicken

The O2 affinity (P50) of erythrocyte suspensions from 18-day chick embryos, from 2-, 5-, 8-, and 14-day chicks, and from mature chickens decreased with increasing concentrations of either CO2 or H+, particularly at a pH near 7.4 and at 37 degrees C. A greater effect on delta P50's was observed from increasing H+ concentration from pH 8.0 to 6.8 in cell suspensions from 18-day embryos (28.8 Torr at 0% CO2) and adult chickens (55.1 Torr at 0% CO2) than from increases in CO2 concentration at any given pH. The Bohr effect (delta log P50/delta pH) in the absence of CO2 was -0.508 and -0.479 for cell suspensions from 18-day chick embryos and adult birds, respectively. The specific effect of CO2 on the Bohr effect, regardless of the CO2 concentration, indicates that the delta P50/0.1 pH is approximately 1.35 and 2.45 Torr for the embryo and adult chicken blood. These results indicate that increasing H+ and CO2 concentrations markedly affect the P50 of chicken blood and that even subtle changes in either could play a significant role physiologically in regulating blood P50 in birds.

Differential sensitivity to ethanol, pentobarbital, and barbital in spontaneously hypertensive and normotensive Wistar-Kyoto rats

Ethanol, pentobarbital, and barbital sleep times and blood levels on awakening were determined in female spontaneously hypertensive (SH) and normotensive Wistar-Kyoto (WK) rats. Ethanol-induced sleep times were significantly longer for SH than for WK and blood ethanol concentrations on awakening were significantly lower in SH than in WK rats. By contrast, pentobarbital and barbital sleep times for SH rats were significantly less than for WK rats and barbiturate blood levels at awakening were significantly higher in SH than in WK rats. No differences were observed between SH and WK rats with respect to the disappearance of ethanol, pentobarbital, and barbital from blood and in the apparent volume of distribution of these drugs. These observations suggest differential CNS sensitivity of the SH and WK rats to ethanol and barbiturates and provide additional support for the notion that there exist differences in the modes of acute action of these drugs.

Familial osteodysplasia associated with trigeminal neuralgia: case report

A 24-year-old woman suffering from left trigeminal neuralgia presented with the familial occurrence of skeletal anomalies simulating Hajdu-Cheney syndrome. She was of a short stature and had low-set ears, protrusion of the bilateral temporal and occipital bones, platybasia, basilar impression, and dental anomaly. Vertebral angiography disclosed marked displacement to the left and dorsally of the basilar artery, which was confirmed during the operation to have compressed the left trigeminal nerve in the cerebellopontine angle narrowed by the unusually protruded bony structure. Cases of Hajdu-Cheney syndrome have occasionally been reported, a few combined with facial spasm, but Hajdu-Cheney syndrome with trigeminal neuralgia is very rare. The patient's family members were surveyed. The possible cause of the neuralgia with its relation to the osteodysplasia is briefly discussed.

Rapid and sensitive analysis of morphine in serum by reversed-phase high performance liquid chromatography with electrochemical detection

A method is described for the determination of morphine in serum. Separation and quantitation are performed by reversed-phase high performance liquid chromatography with electrochemical detection. A sample size of 100 microL or less is required for detection of concentrations as low as 1 to 2 ng/mL. In trials with standard solutions, recovery was 75%. The between-run and within-run coefficients of variation were 7.3% (over the range of 5 to 200 ng/mL) and 9.1% (at 5 ng/mL), respectively.

Determination of picogram levels of brain catecholamines and indoles by a simplified liquid chromatographic electrochemical detection method

A simple and rapid method for the simultaneous determination of norepinephrine, epinephrine, dopamine, 5-hydroxytryptamine and 5-hydroxyindoleacetic acid in rat brain regions by high-performance liquid chromatography (HPLC) with electrochemical detection has been developed. Perchloric acid extracts of the tissue were directly analyzed in the HPLC system. Each of these compounds gave a linear response over the range of 10-320 ng/ml cerebellar homogenate (0.2-6.4 ng on column). Analytical recoveries of these compounds added to the homogenates were complete when compared with standards dissolved in perchloric acid. The average between-run coefficients of variation for all these compounds were lower than 6.7%, over the range of 10-320 ng/ml, whereas the within-run coefficients of variation at 10 ng/ml were lower than 6.9%. Under the present instrumental and mobile phase conditions, all compounds were readily oxidized at 0.72 V vs. a Ag/AgCl reference electrode. The present method has been applied to a study determining the basal levels of these compounds in several rat brain regions as well as levels after medium raphe lesions.

Isolation of a tetracycline-resistance plasmid excised from a chromosomal DNA sequence in Bacillus subtilis

When Bacillus subtilis GSY908 (recE4-) (H. C. Spatz and T. A. Trautner, 1971, Mol. Gen. Genet. 113, 174-190) protoplasts were infected with Staphylococcus aureus plasmid pNS1 specifying tetracycline resistance (Tcr) (N. Noguchi et al., 1983, Gene 21, 105-112), which was modified such that it either could not replicate or did not carry a functional Tcr gene, a plasmid with a molecular weight of 3.1 X 10(6) (4.9 kb) was generated in Tcr phenotypes. This plasmid, named Tcr pNS1981, exhibited completely different restriction endonuclease cleavage patterns to pNS1 and showed only negligible sequence homology in hybridization experiments. Southern hybridization experiments revealed that pNS1981 arises by excision of a B. subtilis chromosomal DNA sequence. No sequence corresponding to pNS1 was detectable on the chromosome of pNS1981-maintaining B. subtilis. The production of pNS1981 was also observed in B. subtilis RM125 (r-Mm-Mrec+) (T. Uozumi et al., 1977, Mol. Gen. Genet. 152, 65-69.) with almost the same frequency as B. subtilis GSY908. Since the recipient B. subtilis Marburg 168 derivatives stated above are sensitive to Tc, the results indicate that information essential for Tcr is under negative regulatory control in the integrated state on the chromosome. Restriction endonuclease analysis suggested that pNS1981 is essentially the same as pBC16, formerly found in B. cereus (K. Bernhard, H. Schrempf, and W. Goebel, 1978, J. Bacteriol. 133, 897-903).

Roughness-Induced Dynamic Loading at Dry and Boundary-Lubricated Sliding Contacts

Measurements of instantaneous normal and frictional forces have been made at smoothly sliding hemispherical steel contacts under nominally dry and boundary-lubricated conditions. Normalized contact force fluctuations generated by surface irregularities are presented. Instantaneous frictional relations are characterized by performing spectral and transfer function computations on the measured signals. The qualitative dynamic frictional behavior is shown to be similar at dry and boundary-lubricated contacts. However, the magnitude of the dynamic loading is considerably reduced in the presence of lubrication. In both cases, an apparent time-varying frictional behavior is found to exist.