Feeding studies in rats with mineral hydrocarbon food grade white oils

This investigation compared the effects of feeding rats diets containing food grade white oil processed by either conventional oleum treatment or the more modern method of catalytic hydrogenation. In two separate experiments, male or female Fischer-344 rats were given free access for 90 days to diets containing 0, 10, 100, 500, 5,000, 10,000, or 20,000 ppm of either oleum-treated white oil (OTWO) or hydrotreated white oil (HTWO). There were no mortalities and no adverse clinical signs associated with feeding either white oil. Treatment-related effects evidenced by hematological, clinical chemical, and pathological changes were generally dose-related and more marked in female than in male rats, and the OTWO caused a greater pathological response than the HTWO. Tissue residues of saturated hydrocarbons were up to 5.2 times higher in female rats than in males. Rats fed 5,000 ppm or more of either white oil showed dose-related alterations in several hematological and clinical chemistry variates associated mainly with hepatic damage or functional alteration. At necropsy, mesenteric lymph nodes were enlarged, and increases in weight of liver, kidney, and spleen were significant. Microscopic changes were characterized by multifocal lipogranulomata in mesenteric lymph node and liver. No changes were observed in rats fed OTWO or HTWO for 90 days at dietary concentrations of 10 or 100 ppm, equivalent to a minimum intake of 0.65 and 6.4 mg/kg/day, respectively. Differences in degree of pathological response associated with each oil may have been due to their differences in specification rather than processing method.

Kynurenic acid analogues with improved affinity and selectivity for the glycine site on the N-methyl-D-aspartate receptor from rat brain

The glycine site on the N-methyl-D-aspartate (NMDA) subtype of receptors for the excitatory neurotransmitter glutamate is a potential target for the development of neuroprotective drugs. We report here two chemical series of glycine site antagonists derived from kynurenic acid (KYNA), with greatly improved potency and selectivity. Disubstitution with chlorine or bromine in the 5- and 7-positions of KYNA increased affinity for [3H]glycine binding sites in rat cortex/hippocampus P2 membranes, with a parallel increase of potency for antagonism of NMDA-evoked responses in the rat cortical wedge preparation. The optimal compound was 5-I,7-Cl-KYNA, with an IC50 for [3H]glycine binding of 29 nM and an apparent Kb in the cortical wedge preparation of 0.41 microM. Reduction of the right-hand ring of 5,7-diCl-KYNA reduced affinity by 10-fold, but this was restored by substitution in the 4-position with the trans-phenylamide and further improved in the trans-benzylamide. The optimal compound was the transphenylurea (L-689,560), with an IC50 of 7.4 nM and an apparent Kb of 0.13 microM. Both series of compounds displayed a high degree of selectivity for the glycine site, having IC50 values of greater than 10 microM versus radioligand binding to the glutamate recognition sites of NMDA, alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA), and kainate receptors and the strychnine-sensitive glycine receptor. Selectivity versus AMPA receptor-mediated responses was also apparent in the rat cortical wedge and in patch-clamp recordings of cortical neurons in culture. Experiments using [3H]dizocilpine (MK-801) binding indicated that 5,7-diBr-KYNA, 5,7-diCl-KYNA, 5-I,7-Cl-KYNA, and L-689,560 all behaved as full antagonists and were competitive with glycine. Patch-clamp recordings of cortical neurons in culture also indicated that NMDA-induced currents were antagonized by competition for the glycine site, and gave no evidence for partial agonist activity. pKi values for 5,7-diBr-KYNA and L-689,560 in these experiments were 7.2 and 7.98, respectively, similar to the affinities of these compounds in the glycine binding assay. The high affinity and selectivity of these new derivatives make them useful tools to investigate the function of the glycine site on the NMDA receptor.

Reversible renal failure in the nephrotic syndrome

Acute, usually reversible, renal failure has been observed in patients with normal or minimally altered glomeruli on renal biopsy. This review aims to examine the clinical features of acute renal failure in these patients and to evaluate factors that may contribute to the reduction in glomerular filtration rate (GFR). In an analysis of 79 cases affecting 75 patients reported in the English literature since 1966, with acute renal failure associated with minimal change disease or mild histopathological changes in glomeruli, the average age was 58 +/- 2 years (mean +/- 5 SEM), urine protein excretion 11.6 +/- 0.6 g/d, and serum albumin level 19 +/- 1 g/L (1.9 +/- 0.1 g/dL). Acute renal failure was documented an average of 29 +/- 5 days after onset of nephrotic syndrome, and persisted for 7 weeks in 62 episodes in the 58 patients in whom recovery of renal function occurred. Fourteen patients died of uremia or required chronic dialysis, and 3 were lost to follow-up. Although plasma volume depletion was sometimes cited as the cause of renal failure, objective signs of hypovolemia were not documented and most patients did not improve after treatment designed to correct volume deficits. In contrast, histopathological changes consistent with acute tubular necrosis (ATN) were observed in at least 60% of cases. Since the pathogenesis of acute renal failure in minimal change nephrotic syndrome is unknown, we evaluated hemodynamic determinants of GFR in patients with minimal change disease with normal or near-normal renal function, and in relevant animal models, to obtain insights into the effect of nephrotic syndrome on GFR. Although acute renal failure is uncommon, GFR is reduced concurrently with nephrotic syndrome in approximately 30% of children and adults. Absolute and effective blood volume and renal plasma flow are relatively well preserved. However, clinical and experimental observations suggest that the glomerular ultrafiltration coefficient may be reduced by as much as 50%. These findings, together with renal biopsy changes in cases with acute renal failure, suggest that severe reductions in GFR in some patients with minimal change nephrotic syndrome may result from an interaction between acute ischemic tissue injury and preexisting intrinsic renal abnormalities.

Disparate interaction of peptide ligand with nascent versus mature class I major histocompatibility complex molecules: comparisons of peptide binding to alternative forms of Ld in cell lysates and the cell surface

To determine the mechanism and structural consequences of peptide binding to class I molecules, we have studied the Ld molecule of the mouse. Previous studies have shown that a significant proportion of surface and intracellular Ld molecules can be detected in an alternative conformation designated Ldalt. Ldalt molecules are non-ligand associated and show weak if any beta 2-microglobulin (beta 2m) association. We report here that Ld molecules have a relatively rapid surface turnover compared with other class I molecules and that exogenous peptide dramatically prolongs Ld surface half-life. By contrast, Ldalt molecules are stably expressed on the surface and their half-life is unaffected by exogenous peptide. To study the surface interaction of peptide with Ld, live cells were incubated with iodinated peptides and Ld molecules were precipitated from cells precoated with monoclonal antibody before lysis. Using this assay, peptide binding to surface Ld molecules was found not to depend upon exchange with exogenous beta 2m, but did correlate with the level of beta 2m association. To study the intracellular interaction of peptide with Ld, cell lysates were used. In cell lysates, peptide was found to convert Ldalt molecules to properly folded Ld. This peptide-induced folding was almost complete at earlier but not later time points in pulse-chase analyses. Furthermore, conversion of Ldalt to Ld was found to affect almost exclusively immature (Endo Hs) class I molecules. Thus intrinsic properties of immature Ldalt molecules or their associated chaperonins are maintained in cell lysates that allow them to undergo de novo folding in vitro. These combined results demonstrate that immature Ldalt molecules are precursors awaiting constituents such as peptide and beta 2m that influence folding, whereas surface Ldalt molecules appear refractory to association with peptide, beta 2m, and consequent folding.

Treatment outcomes of impaired physicians in Oklahoma

Data on one hundred twenty impaired physicians were analyzed to determine treatment outcomes from three differing types of chemical dependency treatment. The data showed that long-term (three to four months) treatment geared specifically to health care professionals was the most effective treatment modality, showing higher rates of favorable treatment outcomes measured by abstinence from alcohol and other drugs.

Binding of substituted and conformationally restricted derivatives of N-(3-phenyl-n-propyl)-1-phenyl-2-aminopropane at sigma-receptors

Certain benzomorphans, such as N-allylnormetazocine, are classical "sigma-opiates" that bind both at sigma and phencyclidine (PCP) binding sites with modest affinity. Recently, we identified N-substituted 2-phenylaminoethane as being the primary sigma-pharmacophore of the benzomorphans and demonstrated that 1-phenyl-2-aminopropane (2) derivatives, depending upon their terminal amine substituents, constitute a novel class of high-affinity sigma-selective agents. With this pharmacophore, it is shown in the present investigation that the aromatic hydroxyl group (a prime feature of all the sigma-opiates) contributes little to the binding of 2 at sigma-sites. It is also demonstrated that an N-substituted aminotetralin moiety (such as 17, a conformationally restricted analogue of 2) may also be considered a sigma-opiate pharmacophore. Unlike the sigma-opiates, derivatives of 2 and 17 display no affinity for PCP sites and must consequently lack those structural features important for the binding of benzomorphans at PCP sites. Because 3-phenylpiperidines and related sigma-ligands also possess a phenylalkylamine imbedded within their structures, we propose that the 2-phenylaminoethane moiety is a common sigma-pharmacophore for derivatives of 2, the 3-phenylpiperidines, and the sigma-opiates.

Identification and exploitation of the sigma-opiate pharmacophore

Certain benzomorphan "sigma-opiates" such as N-allylnormetazocine (NANM) bind at sigma receptors with modest affinity and with little selectivity (i.e., they also bind at phencyclidine or PCP sites). In order to identify the primary pharmacophore of the benzomorphans, we prepared several amine-substituted derivatives of 1-phenyl-2-aminopropane. Several simple alkyl-substituted analogues were shown to bind at sigma sites with affinities comparable to that of NANM itself; among these was the N-benzyl derivative 9 (Ki = 117 nM). Lengthening the spacer between the terminal amine and the phenyl group from one to five methylene units resulted in a significant increase in affinity (e.g. 15, Ki = 6.3 nM). In addition, unlike the benzomorphans, these phenalkylamines do not bind at PCP sites. The results of the present study reveal that (a) the 1-phenyl-2-aminopropane nucleus of the benzomorphans is sufficient for binding at sigma sites provided that the terminal amine is not a primary amine and that (b) introduction of (phenylalkyl)amine substituents affords compounds that represent a new class of high-affinity sigma-selective agents.

Effect of movement and position on muscle activity in tension headache sufferers during and between headaches

This paper presents the results of two studies. In the first, 20 tension headache subjects were evaluated in both a headache and non-headache state on bilateral trapezius and unilateral frontalis electromyographic activity during six positions: standing, bending from the waist, rising, sitting with back unsupported, sitting with back supported, and prone. Results indicated no effect of headache state on either measure. In a second study, 11 of the tension headache sufferers in Study One and 11 age-matched controls were compared on the same measures (controls were assessed two times, with a one-week duration separating evaluations). Results indicated a diagnosis by position interaction, with post-hoc tests revealing the muscle activity of tension headache sufferers to be considerably higher during the prone position than that of non-headache controls. Non-significant trends were found when examining the data for clinically significant abnormalities (90% of the headache sufferers were found to have significant clinical abnormalities).

Cerebral-blood-flow-velocity measurements in neonates: technique and interobserver reliability

The interobserver reliability for absolute cerebral-blood-flow-velocity measurements by colour and duplex Doppler sonography was tested in 32 neonates with a mean birth weight of 1489 (SD 644) g, and a gestational age of 29.9 (SD 3.5) weeks. Using standardized technique, two observers recorded on videotape, the Doppler spectrum of the anterior cerebral artery, the intracranial internal carotid artery and the middle cerebral artery. Peak systolic flow, end diastolic flow, mean flow velocity, resistive index and pulsatility index were computed from 3 consecutive waveforms by each observer. The estimates of interobserver reliability using the intraclass correlation coefficient of the examiners varied from 0.95 to 1.00. Therefore, cerebral blood flow velocity can be reliably measured in premature infants.

Effect of the methylation inhibitors 3-deazaadenosine and 3-deazaaristeromycin on phosphatidylcholine formation in Tetrahymena

The methylation inhibitors 3-deazaadenosine and 3-deazaaristeromycin inhibited the methylation pathway for phosphatidylcholine formation in Tetrahymena. At the same time, the phosphatidylcholine levels within the cell were maintained by increased use of the phosphotransferase pathway. Cell growth was not affected at inhibitor concentrations up to 50 microM but was 50% inhibited at inhibitor concentrations of 100 microM. This growth inhibition was not reversed by the addition of choline to the growth medium. The added choline resulted in greater use of the phosphotransferase pathway, even in uninhibited cultures, but there was no effect on phosphatidylcholine levels, pointing to a much tighter control on phosphatidylcholine formation than exists in animal cells.

(-)PPAP: a new and selective ligand for sigma binding sites

Most agents employed for the investigation of sigma (sigma) binding sites display relatively low affinity for these sites, bind both at sigma sites and at either phencyclidine (PCP) sites or dopamine receptors with similar affinity, and/or produce some dopaminergic activity in vivo. We describe a new agent, (-)PPAP or R(-)-N-(3-phenyl-n-propyl)-1-phenyl-2-aminopropane hydrochloride, that binds with high affinity and selectivity at sigma (IC50 = 24 nM) versus either PCP sites (IC50 greater than 75,000 nM) or D1 and D2 dopamine receptors (IC50 greater than 5,000 nM). The sigma affinity of this agent is comparable to that of the standard ligands (+)-3-PPP and DTG. Furthermore, although (-)PPAP is structurally related to amphetamine, it neither produces nor antagonizes amphetamine-like stimulus effect in rats trained to discriminate 1 mg/kg of S(+)amphetamine from saline.

Accumulation of human apolipoprotein E in the plasma of transgenic mice

Three separate lines of transgenic mice were created with integrated copies of an 11.1-kilobase pair human DNA fragment containing the apolipoprotein (apo) E gene. The endogenous mouse apoE gene is primarily expressed in the liver with varying levels of expression in other tissues. However, in all three transgenic lines high levels of human apoE mRNA were detected only in the kidney, with lower levels found in the liver and other tissues; despite this profile of human apoE mRNA, human apoE was found in the plasma of the transgenic mice at levels comparable to those found in human plasma. All of the human apoE in the plasma of the transgenic mice was associated with lipoproteins. These results suggest that the domain responsible for the high level of apoE expression in liver lies outside of the microinjected DNA fragment and that an ectopic site of expression of an introduced gene may be permissive for the accumulation of its protein in plasma.

Role of hydrogen bonding in ligand interaction with the N-methyl-D-aspartate receptor ion channel

Displacement of [3H]MK-801 (dizocilpine, 1) binding to rat brain membranes has been used to evaluate the affinities of novel dibenzocycloalkenimines related to 1 for the ion channel binding site (also known as the phencyclidine or PCP receptor) on the N-methyl-D-aspartate (NMDA) subtype of excitory amino acid receptor. In common with many other agents having actions in the central nervous system, these compounds contain a hydrophobic aromatic moiety and a basic nitrogen atom. The conformational rigidity of these ligands provides a unique opportunity to evaluate the importance of specific geometrical properties that influence active-site recognition, in particular the role of the nitrogen atom in hydrogen-bonding interactions. The relative affinities (IC50s) of hydrocarbon-substituted analogues of 1 and ring homologated cyclooctenimines illustrate the importance of size-limited hydrophobic binding of both aryl rings and of the quaternary C-5 methyl group. Analysis of the binding of a series of the 10 available structurally rigid dibenzoazabicyclo[x.y.z]alkanes, by using molecular modeling techniques, uncovered a highly significant correlation between affinity and a proposed ligand-active site hydrogen bonding vector (r = 0.950, p less than 0.001). These results are used to generate a pharmacophore of the MK-801 recognition site/PCP receptor, which accounts for the binding of all of the known ligands.

Subglottic cysts in the premature infant

Supraglottic cysts in the newborn are a well-recognized entity, but subglottic cysts have been rarely reported. Over the past 6 years we have observed subglottic cysts in nine patients with relatively long intubations from the neonatal intensive care unit of two university hospitals. Most frequently the patients were extubated and did well for weeks or months, but then they had progressive biphasic stridor. On endoscopy the patients had a subglottic stenosis that was irregular but with a smooth mucosal lining. Usually the cysts were apparent, but in two patients the mucosa was thickened and the patients were treated as a subglottic stenosis with tracheostomy. These subglottic cysts were recognized at the time of laryngotracheoplasty. In six patients the cysts were managed either by marsupialization with cup forceps, endoscopic diathermy, or carbon dioxide laser without recurrence. It is our belief that this condition is most likely due to scarring and obstruction of mucus glands of the subglottic area from prolonged intubation. This entity should be recognized and looked for in the neonate who has an acquired subglottic stenosis and should first be treated conservatively with endoscopic marsupialization.

Recovery of hepatitis A virus from a water supply responsible for a common source outbreak of hepatitis A

An outbreak of hepatitis A occurred in a north Georgia trailer park served by a private well. Of 18 residents who were serosusceptible to hepatitis A virus (HAV), 16 (89%) developed hepatitis A. Well water samples were collected 3 months after illness onset in the index case and 28 days after illness onset in the last trailer park resident. Hepatitis A virus antigen (HAVAg) was detected in the samples by enzyme immunoassay from three of the five cell lines following two 30-day passages and from a fourth cell line following a third passage of 21 days.

A light and electron microscope investigation of the transfer cell region of maize caryopses

The transfer cell zones from 23-day postpollination corn caryopses were examined using light and electron microscopes and X-ray elemental analysis. The transfer cells were sectioned in cross and longitudinal planes and were characterized by having numerous cell-wall extensions in the form of anastomosing lamellae. The most basal transfer cells had more cell-wall extensions than those that were successively deeper in the endosperm. Cytoplasm, rich with mitochondria, filled the interstices of cell-wall extensions, and many vesiculate areas could be found along the plasma membrane. Some transfer cells contained crystals within plastids. The crystals were composed of magnesium, phosphorus, calcium, and zinc. Other cells had large aggregations of endoplasmic reticulum that were often in close association with mitochondria or unidentified, single membrane bounded organelles. When viewed in cross section, the cell-wall extensions of contiguous cells tended to originate from common loci. Plasmodesmata were absent in the bottom parts of the basal transfer cells where they contacted the maternal tissue but were abundant in the upper parts of these cells and in the transfer cells found deeper in the endosperm. The plasmodesmata were found in clusters and alternated with the wall extension areas.

Aesthetic preference and syntactic prototypicality in music: 'tis the gift to be simple

In the dominant aesthetic theory, composers are said to use unpredictable events to tease the listener, and make music optimally challenging and therefore aesthetically pleasing. We tested this claim that events optimally discrepant from a schema will be most pleasing. Experts and novices evaluated harmonic progressions at seven levels of syntactic prototypicality. Four results emerged: (1) even novices were extremely sensitive to syntactic atypicality; (2) all subjects found atypical progressions more interesting and complex; (3) novices and undergraduate music students preferred harmonic prototypes, contrary to most aesthetic theories; (4) only music graduate students preferred atypical progressions. We discuss the striking sensitivity of novices to harmonic syntax. We describe differences between an aesthetic theory based on information and uncertainty, and one based on schemas and schema divergence. We also consider the tonal conservatism of most subjects. This conservatism constrains aesthetic theories, and may have implications for music's stylistic evolution.

Epidemiologic evidence that prior antimicrobial exposure decreases resistance to infection by antimicrobial-sensitive Salmonella

Exposure to antimicrobials is known to increase the risk of infection with antimicrobial-resistant strains of Salmonella, but this effect has not been previously demonstrated with antimicrobial-sensitive strains. The effect of prior antimicrobial exposure was studied during a multistate outbreak of salmonellosis caused by an antimicrobial-sensitive strain of Salmonella havana: 19 (26%) of 72 persons infected had taken an antimicrobial within 30 days before onset of symptoms. Antimicrobial therapy was begun a mean of 15.9 days before and stopped a mean of 7.9 days before onset. In a case-control study, 11 (31%) of 35 case-patients had taken antimicrobials within 30 days of onset compared with 9 (13%) of 70 age- and neighborhood-matched controls (matched odds ratio, 4.3; 95% confidence interval, 1.3, 13.5). The association remained when controlled for the presence of underlying illness or immunosuppression. Prior antimicrobial exposure appears to increase the risk of infection with antimicrobial-sensitive and resistant strains of Salmonella. The delay between antimicrobial use and onset of symptoms suggests that the effect may be due to prolonged alteration of the colonic bacterial flora, resulting in decreased resistance to colonization.