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Biomedical subjects

R Wolf

Publications and source records attributed to R Wolf.

At least 145 records · Page 8Linked to original sources
PubMed1994

Circadian rhythm of serum and lymph apolipoprotein AIV in ad libitum-fed and fasted rats.

The aim of the present study was to determine if there is a circadian rhythm in serum and lymph apolipoprotein (apo) AIV and what factors determine this rhythm. Male Sprague-Dawley rats with chronic right atrial catheter were housed in a room illuminated from 0600 to 1800. With ad libitum feeding, serum apo AIV concentration showed a circadian rhythm concomitant with the feeding pattern. In 24-h fasted rats, the serum apo AIV concentration maintained a circadian rhythm and was high during the dark. With mesenteric lymph diversion, serum apo AIV concentration diminished and the circadian rhythm was abolished. The lymph flow, lymph apo AIV, cholesterol, triacylglycerol, and phospholipid contents all exhibited the same circadian rhythm in fasting, with the levels higher in the dark. These circadian rhythms were abolished after bile diversion. In conclusion, serum apo AIV in ad libitum-fed and fasted rats exhibits a circadian rhythm governed by lymph apo AIV output. Furthermore, bile was an important determinant of the circadian rhythm of lymph flow, lymph apo AIV, triacylglycerol, cholesterol, and phospholipid output.

Animals↗
PubMed1994

An active amide group in the molecule of drugs that induce pemphigus: a casual or causal relationship?

Traditionally, drugs that are capable of inducing pemphigus are divided into two main groups according to their chemical structure, in particular, the existence of a sulfhydryl group in their molecule. Thus, two groups are formed: (1) drugs containing a sulfhydryl radical (thiol drugs or SH drugs) and (2) nonthiol or other drugs. Much emphasis has been put on the role of the sulfhydryl group in the pathogenesis of drug-induced pemphigus. The effects of this group have been extensively studied, and a logical paradigm on the mode of its action has been created. However, no attempt has been made to search for other biochemical radicals which might have an influence on the activation/triggering of this disease. The aim of the present report is to draw attention to a chemical group common to the molecule of several drugs that have been associated with the induction of pemphigus. Careful analysis of the chemical structure of nonthiol drugs known to induce pemphigus revealed that several of them share an active amide group in their molecule. We believe that this group might be responsible for the induction of the disease; thus, a third group of drugs capable of triggering pemphigus can be formed, namely drugs containing an active amide group. Several drugs of this group are discussed.

Amides↗
PubMed1994

Has mildness replaced cleanliness next to godliness?

Over the past 30 years we have witnessed a change in our approach to soaps. The turning point was, in fact, the publication of an article by Frosch and Kligman in 1979, in which they described a new method for assessing the irritancy of soaps. They maintained that the chief weakness of the usage tests in the past was that the reactions under normal usage conditions were weak and did not discriminate adequately between different soaps. They proposed a test, called the soap chamber test, which was conducted under extreme conditions, on people known to have a sensitive skin, thereby resulting in strong reactions that emphasized the slight differences between the various soaps. Frosch and Kligman's work opened up a whole new era in the field of assessment of soap quality. Following their initial studies, many other studies were conducted, including the exaggerated use tests, often in conjunction with instrumental methods of evaluation, such as measurement of transepidermal water loss, electrical conductance, skin color and blood flow, and other tests designed to evaluate the irritation potential of various soaps. All those tests had a common purpose: to achieve extreme conditions which would provide greater sensitivity and discriminating power and would accentuate and emphasize the differences between soaps as much as possible: the greater the discrimination and the differences between the products, the more efficient and useful the test. The introduction and publication of tests such as those completely changed out approach to soaps. The sought-after qualities in a soap became safety, mildness, gentleness, less irritation, less drying--in particular, gentleness and mildness were emphasized.(ABSTRACT TRUNCATED AT 250 WORDS)

Dermatitis, Irritant↗
PubMed1994

Possible nutritional factors in induced pemphigus.

Today it is generally accepted that every drug that possesses an active thiol group in its molecule is capable of inducing pemphigus. Some plants, in particular those belonging to the Allium group, contain several active compounds with stable disulfide and thiol groups in their molecule. The Allium group contains many important vegetables like onion, leek and garlic. Examples of molecules with an active thiol group are: CH2 = CH-CH2-S-S-CH2-CH = CH2 (diallyl disulfide) or CH2 = CH-CH2-S(O)S-CH2-CH = CH2 (allicin). It is suggested that some foods, in particular vegetables of the Allium group that contain active thiol groups in their molecule, could contribute to the induction of pemphigus. In general, nutritional factors should be added to the list of exogenous factors that are capable of inducing pemphigus.

Allium↗
PubMed1994

Modulation of ischemia/reperfusion-induced microvascular dysfunction by nitric oxide.

Leukocyte-endothelial cell adhesion and an altered metabolism of endothelial cell-derived nitric oxide (NO) have been implicated in the microvascular dysfunction associated with ischemia/reperfusion (I/R). The objective of this study was to determine whether NO donors can attenuate the reperfusion-induced increase in venular albumin leakage via an effect on leukocyte-endothelial cell adhesion. Leukocyte adherence and emigration as well as albumin extravasation were monitored in single postcapillary venules in rat mesentery subjected to 20 minutes of ischemia followed by 30 minutes of reperfusion. This I/R protocol elicits significant leukocyte adherence and emigration as well as a profound albumin leakage response. Superfusion of the mesenteric microcirculation with the NO donors sodium nitroprusside, spermine-NO, and SIN1 significantly reduced the I/R-induced leukocyte adherence/emigration and albumin leakage in postcapillary venules, whereas neither spermine nor the NO synthase inhibitor NG-nitro-L-arginine methyl ester affected the I/R-induced responses. Platelet-leukocyte aggregation and mast cell degranulation were also observed in the postischemic mesentery, and the responses were also attenuated by the NO donors. Plasma nitrate/nitrite levels in the superior mesenteric vein were significantly reduced by I/R. The results of this study indicate that I/R-induced microvascular dysfunction (albumin leakage) is attenuated by NO and that the protective effect of NO donors may be related to their ability to reduce leukocyte-endothelial cell and leukocyte-platelet interactions and/or mast cell degranulation.

Animals↗
PubMed1994

Role of H1 receptors and P-selectin in histamine-induced leukocyte rolling and adhesion in postcapillary venules.

The objective of this study was to define the nature, magnitude, and mechanisms of histamine-induced leukocyte-endothelial cell interactions in postcapillary venules of the rat mesentery using intravital microscopic techniques. Superfusion of the mesentery with histamine (10(-7)-10(-5) M) resulted in a dose-related increase in the number of rolling leukocytes, a reduction in rolling velocity, and an increased clearance of FITC-labeled rat albumin from blood to superfusate. The histamine-induced recruitment of rolling leukocytes and increased albumin clearance were prevented by histamine H1 (hydroxyzine, diphenhydramine) but not H2 (cimetidine) receptor antagonists. Because histamine induces expression of the adhesion molecule P-selectin in cultured endothelial cells, a monoclonal antibody directed against rat P-selectin and soluble sialyl-LewisX oligosaccharide (the carbohydrate ligand to P-selectin) were also tested as inhibitors. Both were effective in preventing the histamine-induced recruitment of rolling leukocytes, but neither agent attenuated the increased albumin clearance. These observations suggest that (a) histamine recruits rolling leukocytes and increases albumin leakage in postcapillary venules via H1 receptor activation, (b) histamine-induced recruitment of rolling leukocytes is mediated in part by P-selectin expressed on the endothelial cell surface, and (c) the histamine-induced vascular albumin leakage is unrelated to leukocyte-endothelial cell adhesion. Our results are consistent with the view that histamine may act as a mediator of acute inflammatory reactions.

Animals↗
PubMed1994

Clostridium difficile toxin A-induced microvascular dysfunction. Role of histamine.

Clostridium difficile toxin A (Tx-A) mediates secretion and inflammation in experimental enterocolitis. Intravital video microscopy was used to define the mechanisms that underlie the inflammatory reactions elicited by direct exposure of the microvasculature to Tx-A. Leukocyte adherence and emigration, leukocyte-platelet aggregation, and extravasation of FITC-albumin were monitored in rat mesenteric venules exposed to Tx-A. Significant increases in leukocyte adherence and emigration (LAE) and albumin leakage were noted within 15-30 min of Tx-A exposure. These responses were accompanied by mast cell degranulation and the formation of platelet-leukocyte aggregates. The Tx-A-induced increases in LAE and albumin leakage were significantly attenuated by pretreatment with either monoclonal antibodies (mAbs) directed against the leukocyte adhesion glycoproteins, CD11/CD18, intercellular adhesion molecule-1, and P-selectin (but not E-selectin) or with sialyl Lewis x, a counter-receptor for P-selectin. The mast cell stabilizer, lodoxamide, an H1- (but not an H2-) receptor antagonist, and diamine oxidase (histaminase) were also effective in reducing the LAE and albumin leakage elicited by Tx-A. The platelet-leukocyte aggregation response was blunted by an mAb against P-selectin, sialyl Lewis x, and the H1-receptor antagonist. These observations indicate that Tx-A induces a leukocyte-dependent leakage of albumin from postcapillary venules. Mast cell-derived histamine appears to mediate at least part of the leukocyte-endothelial cell adhesion and platelet-leukocyte aggregation by engaging H1-receptors on endothelial cells and platelets to increase the expression of P-selectin. The adhesion glycoproteins CD11/CD18 and intercellular adhesion molecule-1 also contribute to the inflammatory responses elicited by toxin A.

Animals↗
PubMed1994

Headache, thrombolytic therapy, and chronic subdural hemorrhage--a case report.

Subdural hematomas are well known but infrequent complications of thrombolytic therapy. Although these are usually associated with head trauma, the authors describe a case of a patient who received a particularly aggressive thrombolytic regimen and presented six months later with complaints of nothing more than a headache resistant to medical therapy, without associated neurologic manifestations, which was finally diagnosed as a chronic subdural hematoma by computerized tomography. In the era of thrombolysis, physicians should maintain a heightened index of suspicion for subdural hematoma in patients complaining of headache.

Aged↗
PubMed1994

Leukocytoclastic vasculitis: another coumarin-induced hemorrhagic reaction.

A 67-year-old male developed a hemorrhagic eruption 4 weeks after initiation of coumarin therapy. Examination revealed a well-demarcated, purple patch with a central hemorrhagic bulla on the anterior aspect of the leg, surrounded by small petechiae. Histological examination of the purple plaque revealed leukocytoclastic vasculitis. It is suggested that leukocytoclastic vasculitis be considered in the differential diagnosis of coumarin-induced hemorrhagic reactions.

Aged↗
PubMed1994

The central complex of Drosophila melanogaster is involved in flight control: studies on mutants and mosaics of the gene ellipsoid body open.

Visual flight control is studied in three mutant alleles of the gene ellipsoid body open (ebo) of Drosophila melanogaster. In mutant ebo flies the central complex is disturbed to varying degrees. Defects range from a small opening in the ellipsoid body to the dissociation of the ring into two parts, a cleft in the fan-shaped body and hypoplasia in the protocerebral bridge. Other parts of the brain are not visibly affected. Flight behavior is normal with respect to the amplitude of the optomotor response and to the object response (single rotating stripe). A reduced amplitude in the small random oscillations of the torque trace (yaw torque activity), however, is found in all three alleles. In two of them the frequency of torque spikes is reduced. In the allele ebo678 the dynamics of the optomotor response is altered. Upon reversal of the direction of rotation mutant flies take longer than wild type to shift their yaw torque to the new response level (optomotor reversal time). Finally, these flies also behave abnormally in the flight simulator in which their yaw torque controls the angular velocity of the panorama. Many ebo678 flies fixate a single stripe less persistently than normal flies, some even trying to fly away from it (antifixation). In ebo678 gynandromorphs the four behavioral phenotypes ("yaw torque activity", "torque spike frequency", "on-target fixation" and "optomotor reversal time") are all highly correlated with the phenotype of the ellipsoid body. Yaw torque activity and torque spike frequency in addition are correlated with the phenotype of the thorax suggesting that these behavioral defects are in part caused by mutant influences on the ventral ganglion. The results support the hypothesis that the central complex is involved in the control of flight behavior.

Animals↗
PubMed1994

Effects of Valsalva's manoeuvre on intraocular pressure.

We examined the effects of breath holding against a closed glottis (Valsalva's manoeuvre) on intraocular pressure (IOP) in four groups of volunteer subjects: 37 healthy young control subjects, 10 patients with chronic open-angle glaucoma, 11 age-matched control subjects and 8 glaucoma suspects. IOP was recorded by one person using a Digilab 30R/T Pneuma-Tonometer. Chart recordings of the IOP were measured independently by a second investigator. Recordings were taken before, during and 5 minutes after the seated subject exhaled into an aneroid manometer to a pressure of 25 to 35 cm H2O. There was marked variability in the individual responses to Valsalva's manoeuvre in all four groups, with substantial increases (to +9.5 mm Hg) and decreases (to -4.0 mm Hg) in IOP seen. The mean change in IOP during Valsalva's manoeuvre was a small, statistically insignificant decrease in all four groups. The mean change in IOP following Valsalva's manoeuvre was a larger, but still clinically small, decrease. The clinician should be aware of the individual variability in IOP changes with Valsalva's manoeuvre.

Adult↗
PubMed1994

Psoriasiform eruption induced by anticonvulsants.

We present findings from three patients who experienced a psoriasiform eruption apparently due to the antiepileptic agents sodium valproate and carbamazepine. The causal relationship between the drug and the eruption has been based mainly on circumstantial evidence and is further strengthened by the positive result of one or two in vitro tests: the macrophage migration inhibition (MIF) test and the indirect rat mast cell degranulation (MCD) test. Sodium valproate and carbamazepine, antiepileptic drugs that are associated with a relatively low rate of adverse cutaneous reactions, should be added to the growing list of drugs that produce psoriasiform eruptions. A drug-induced psoriasiform eruption due to these drugs seems to be more common than previously reported. Physicians should be aware of this type of reaction. Early detection of these cases has practical importance since the identification and elimination of the causative drug is essential for therapy success.

Adult↗
PubMed1993

Visual pattern recognition in Drosophila involves retinotopic matching.

Honeybees remember the shapes of flowers and are guided by visual landmarks on their foraging trips. How insects recognize visual patterns is poorly understood. Experiments suggest that they try to match retinotopically the incoming visual pattern with a previously stored memory image. But bees can be conditioned to individual pattern parameters such as orientation of contours, colour or size. These and other results are difficult to reconcile with simple template matching. In such investigations, freely moving animals are observed; their behaviour and visual input, therefore, are not well known. Mostly, processing strategies are inferred from stimulus design. We have studied visual pattern recognition with tethered flies (Drosophila melanogaster) in a flight simulator and report here that flies store visual images at, or together with, fixed retinal positions and can retrieve them from there only. Position invariance, an acknowledged property of human pattern recognition, may not exist as a primary mechanism in insects.

Animals↗
PubMed1993

Influence of partial sleep deprivation on the secretion of thyrotropin, thyroid hormones, growth hormone, prolactin, luteinizing hormone, follicle stimulating hormone, and estradiol in healthy young women.

The influence of partial sleep deprivation during the second half of the night on the secretion of thyroid stimulating hormone (TSH), thyroxin (T4), free T4 (fT4), triiodothyronine (T3), prolactin (PRL), growth hormone (GH), luteinizing hormone (LH), follicle stimulating hormone (FSH), and estradiol (E2) was investigated in 10 healthy young women. Blood samples were drawn at hourly intervals over a 64-hour period (i.e., 3 consecutive days and nights). During night 2, all subjects were awakened at 1:30 a.m. During partial sleep deprivation, TSH concentrations increased significantly and remained elevated throughout the following day. Levels of T4, fT4, and T3 were enhanced during the partial sleep deprivation hours only, and changes in these hormones seemed to be independent of TSH. PRL levels decreased, LH and E2 concentrations increased, and GH and FSH secretion remained unchanged during partial sleep deprivation. This pattern of change of different endocrine axes during partial sleep deprivation resembles those seen after total sleep deprivation, suggesting that similar neurochemical changes are induced by both forms of antidepressant therapy. The late evening GH peak occurred almost exclusively before the onset of sleep. Partial sleep deprivation did not influence the chronobiological profiles of any of the hormones investigated. The chemical changes underlying these alterations are speculated to involve enhancement of central norepinephrine and dopamine activity with a concomitant increase in the activity of the sympathetic nervous system.

Adult↗
PubMed1993

Granted publications: taken for granted?

Highly respected journals now relatively rarely publish independent research which is not grant-supported. This may lead to a reduction in the publication of innovative work.

Australia↗
PubMed1993

DNA strand breakage and DNA adducts in lymphocytes of oral cancer patients.

In lymphocytes of 12 oral cancer patients (and two control groups) the frequencies of DNA single-strand breaks and DNA-protein cross-linking were determined by alkaline filter elution. We found elevated DNA elution rates, which must be interpreted as an increased strand breakage frequency. There were significant correlations between the DNA strand breakage frequency and smoking habits. Using the 32P-postlabelling assay we determined the DNA adduct level in lymphocytes of 23 oral cancer patients (and two control groups). No significant influence of smoking habit on the DNA adduct level could be detected. There was a significant correlation between the DNA adduct level and the gamma-glutamyltranspeptidase (GGT) value, suggesting systemic influences of alcohol drinking habits on the adduct level.

Adult↗