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Biomedical subjects

W Jordan

Publications and source records attributed to W Jordan.

At least 19 recordsLinked to original sources
PubMed2005

Evaluation of oxidative stress measurements in obstructive sleep apnea syndrome.

Assessment of reactive oxygen species (ROS) is highly important in neurodegenerative disorders and neuroleptic treatment. However, conflicting results have been reported, which may arise from methodological difficulties. Obstructive sleep apnea (OSA) syndrome with episodic hypoxia-reoxygenation is proposed as a human model for the investigation of ROS measurements. Despite a broad analytical approach comprising lipid peroxidation and amino acid oxidation products, oxidative DNA damage, and activity of the antioxidant defense, only plasma malondialdehyde (MDA) and urinary o,o'-dityrosine seemed to be appropriate, robust biomarkers of oxidative stress, which are also simple enough for routine clinical use. MDA concentrations correlated with a duration of nocturnal desaturation below 85% (r = 0.77, p<0.0005), and o,o'-dityrosine levels decreased after therapy (p<0.05) as a function of baseline concentrations (r = -0.61, p<0.05). Gender effects in ROS generation also have to be considered. At present, we recommend the application of several oxidative stress measurements at different time points, preferably involving plasma MDA and urinary o,o'-dityrosine.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed2004

CPAP-therapy effectively lowers serum homocysteine in obstructive sleep apnea syndrome.

Assessment of serum total homocysteine (tHcy) in patients with obstructive sleep apnea (OSA) syndrome is highly relevant since both are strongly associated with stroke and cognitive dysfunction. Seven of 16 untreated OSA patients showed tHcy levels exceeding 11.7 micromol/l. The circadian pattern of serum tHcy in untreated and treated patients (p < 0.001) implied a diagnostic impact of blood sampling time. Treatment with continuous positive airway pressure (CPAP) effectively lowered tHcy levels in patients by about 30% (p < 0.005) and thus probably the (hyper)homocysteinemia-related cognitive dysfunction and the risk for cardio-/cerebrovascular diseases.

Chromatography, High Pressure Liquid↗
PubMed2003

The sleep-improving effects of doxepin are paralleled by a normalized plasma cortisol secretion in primary insomnia. A placebo-controlled, double-blind, randomized, cross-over study followed by an open treatment over 3 weeks.

RATIONALE: In primary care, sedating antidepressants are often used for treating insomnia, although their underlying sleep-promoting mechanisms are only incompletely understood. Since enhanced evening and nocturnal plasma cortisol levels are supposed to maintain insomniac sleep complaints, a functional link between sleep and cortisol secretion in the mode of action of antidepressants in insomnia might be suspected. OBJECTIVES: We therefore investigated the effects of the tricyclic antidepressant doxepin on nocturnal sleep and plasma cortisol concentration in ten patients (age 41.3+/-9.5 years) with chronic primary insomnia between 1700 hours and 0800 hours. METHODS: Single infusions of placebo and 25 mg doxepin were applied following a double-blind, randomized cross-over design. Afterward, all patients received 25 mg doxepin p.o. for 3 weeks in an open-study design. RESULTS: Both doxepin application forms improved sleep significantly and reduced mean cortisol levels from 9.0+/-1.7 microg/l (single placebo i.v.) to 7.5+/-1.6 microg/l (single doxepin i.v.) or 7.6+/-2.0 microg/l (subchronic doxepin p.o.). The duration of the quiescent period of the cortisol rhythm was significantly prolonged following both doxepin administrations compared with placebo. CONCLUSIONS: The results implicate that the sleep-improving effects of doxepin are mediated at least in part by a normalization of hypothalamic-pituitary-adrenal axis functions. Although in some patients rebound insomnia and specific side effects must be considered, our findings give a further rationale for the use of antidepressants in the treatment of primary insomnia.

Adult↗
PubMed2002

Biochemical markers of cerebrovascular injury in sleep apnoea syndrome.

Sleep apnoea syndrome (SAS) is a known risk factor for vascular diseases and stroke. Structural brain damage, manifesting as an overt neurological deficit or more subtly as cognitive dysfunction, is a frequent symptom in SAS. The presence of a biochemical marker of cerebral injury would be of great benefit in SAS to screen for even small brain damage and to monitor efficiacy of therapy. Therefore, in 10 patients with mild SAS (age 50.8+/-9.9 yrs, respiratory disturbance index (RDI) 18+/-3.6, lowest arterial oxygen saturation (min Sa,O2) 80.5+/-4.06%) and nine patients with severe SAS (age 50.3+/-11.5 yrs, RDI 75.4+/-21.7, min Sa,O2 56.56+/-14.58%), serum concentrations of neuron-specific enolase (NSE), S-100beta protein, and beta-trace were measured just before and after sleep using commercially available assays. Only serum levels in the normal range could be found, independent of when the blood was taken or the degree of SAS. Structural cerebral injury caused by sleep apnoea syndrome in patients without neurological symptoms or previous cerebrovascular events may be too small to produce a measurable increase in S-100beta, neuron-specific enolase and beta-trace serum concentrations or subclinical cerebral damage may be outside the lower detection limits of the analytical methods which were used. There is a need for biochemical markers and more sensitive methods for detecting small cerebral injury in sleep apnoea syndrome.

Adult↗
PubMed2001

"Accomodated" pig endothelial cells promote nitric oxide-dependent Th-2 cytokine responses from human T cells.

BACKGROUND: Cardiac and renal allo- and xenografts can become naturally resistant to vascular rejection. Understanding this process of "accommodation" would enhance our understanding of vascular inflammatory responses and have implications for immune manipulation and tolerance induction. A feature of these grafts is infiltration by leukocytes secreting a Th-2 pattern of cytokines. METHODS: HLA-DR-1-transfected, immortalized porcine endothelial cells (IPEC) were incubated with polyclonal human immunoglobulin G (IgG) for 6 days before incubation with purified human CD4+ T cells. RESULTS: IgG-incubated IPEC stimulated a normal proliferative response from alloreactive T cells. However, interferon (IFN)-gamma levels were significantly reduced, whereas interleukin (IL)-5 and IL-10 were maintained at levels equivalent to those stimulated by control IPEC. Cognate interaction between T cells and IPEC was not required for this effect, because IgG-incubated, MHC-class II-negative IPEC caused reduced IFN-gamma secretion during a response to human Epstein-Barr virus-transformed B cells. Experiments with the nitric oxide (NO) donor, (z)-1-2-[2-Aminoethyl)-N-(2-ammonioethyl)amino]diazen-1-ium-1,2-diolate (DETA-NO), and the NO synthase inhibitor, NG-monomethyl-L-arginine.monoacetate (L-NMMA), showed that NO released by the IgG-incubated IPEC was actively involved in the development of this phenotype. CONCLUSIONS: These data suggest a novel, IgG-mediated, NO-dependent mechanism by which endothelial cells (EC) influence T cell responsiveness and that the Th-2 cytokine skewing seen in "accommodated" grafts may be a secondary phenomenon, resulting from the T-EC interactions.

Animals↗
PubMed2001

Mutual exclusion of apoptosis and hsp70 in human vein intimal hyperplasia in vitro.

BACKGROUND: Apoptosis of vascular smooth muscle cells (VSMC) plays a role in physiological vascular remodeling, as well as in disease states such as atherosclerosis and restenosis after angioplasty. Heat shock protein 70 (hsp70) may protect the cell against apoptosis and/or necrosis. In this study, we examined hsp70 expression and its temporal relationship to cell survival or death in a model of intimal vein hyperplasia in vitro. METHODS: Segments of human saphenous veins were placed into culture. At different days vein segments were serum-starved or exposed to heat shock. Apoptosis and hsp70 expression were analyzed by Western blot, immunohistochemistry, and TUNEL assay. RESULTS: A marked intimal vein hyperplasia developed after 14 days of culture when compared with baseline. hsp70 was present at baseline and disappeared during culture. Heating during culture could not up-regulate hsp70. The apoptotic markers were absent at baseline and present during normal culture. Conversely, serum starvation stimulated strong hsp70 expression coincidental with the disappearance of apoptotic markers. CONCLUSIONS: Stimulation of veins during culture with serum resulted in hyperplasia, apoptosis, and inhibition of hsp70 expression. Down-regulation of hsp70 may permit apoptosis and vessel wall remodeling in this model.

Apoptosis↗
PubMed2001

Fragrance contact dermatitis: a worldwide multicenter investigation (Part II).

The purpose of this study was to determine the frequency of responses to selected fragrance materials in patients who were fragrance sensitive. 178 patients were evaluated in 8 centers worldwide with a fragrance mix (FM) and 20 other fragrance materials. Reaction to the fragrance mixture (FM) occurred in 78.7% of the subjects. Substances reacting at a rate of 2% or higher included jasmine absolute, geranium oil bourbon, l-citronellol, spearmint oil, 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta-gamma-2-benzopyran, omega-6-hexadecenlactone, dimethyltetrahydrobenzaldehyde (isomer mixture), and alpha-amylcinnamaldehyde. These chemicals should be furthur evaluated to corroborate their allergenicity. We are constantly looking for new fragrance allergens to extend the diagnostic capability of the fragrance mix (FM).

Allergens↗
PubMed2000

High-risk behaviors during incarceration in African-American men treated for HIV at three Los Angeles public medical centers.

OBJECTIVES: This paper describes research that examined the association between high-risk sexual and drug-using behaviors during incarceration and HIV infection for African-American men receiving HIV care at three public medical centers in Los Angeles County (LAC), California. METHODS: A case-control study was conducted in which 305 HIV-infected African-American men and 305 neighborhood controls, ages 20 to 49, were frequency-matched by age. RESULTS: After controlling for anal sex while not incarcerated, we found no association between anal sex during incarceration and HIV (odds ratio [OR], 1.1; 95% confidence interval [CI], 0.6-2.2). Among men with a history of incarceration (n = 332), the percentage reporting anal sex with men outside of incarceration (45%) was greater than those reporting anal sex while incarcerated (16%). Injection drug use (IDU) during incarceration was also not associated with HIV when controlling for IDU outside of incarceration (OR, 1.6; 95% CI, 0.5- 4.9). Increased time in jail or prison was associated with less HIV infection (p =.001). CONCLUSIONS: Although high-risk behaviors are more common in the community than in the incarcerated setting for this study group, incarcerated populations represent a high-risk group for whom access to prevention messages is limited. Periods of incarceration represent a unique opportunity to convey prevention messages that focus on high-risk behaviors outside the incarcerated setting.

Adult↗
PubMed1999

First results on daytime submandibular electrostimulation of suprahyoidal muscles to prevent night-time hypopharyngeal collapse in obstructive sleep apnea syndrome.

Daytime submandibular electrostimulation (dSE) of suprahyoidal muscles was applied to prevent sleep-associated collapse of the tongue into the hypopharyngeal airway. By placing the stimulatory electrodes intra- and extraorally, recruitment of stimulated muscle fibers at low current densities was improved. The significant impact of electrostimulation on suprahyoidal muscle force was initially demonstrated in healthy controls as compared to placebo-treated volunteers. The morphology of suprahyoidal muscles was not affected by this treatment. A patient with obstructive sleep apnea syndrome initially presented with a respiratory disturbance index (RDI) of 13.2, an oxygen desaturation index of 23 and a minimal oxygen saturation of 75%. After two weeks of placebo treatment (TENS-stimulation), respiratory parameters remained unchanged. Two weeks of dSE treatment, however, improved the RDI to 3.9, the oxygen desaturation index from 23 to 2.8 and the minimal oxygen saturation from 75% to 88%. 3D-sonography showed considerable hypertrophy of the stimulated muscles. These results indicate that dSE may prevent episodes of apnea induced by sleep-associated hypopharyngeal collapse of the tongue.

Adult↗
PubMed1998

Predicting the effect of carotid artery occlusion during carotid endarterectomy: comparing transcranial doppler measurements and cerebral angiography.

BACKGROUND AND PURPOSE: We correlated the mean transcranial Doppler blood flow velocity (FVm) during carotid endarterectomy with the functional collateral pathway(s) documented by angiography. METHODS: Three patient groups were established: group 1 was dependent on the anterior communicating artery, group 2 on the anterior communicating artery and ipsilateral posterior communicating artery, and group 3 on the ipsilateral posterior communicating artery. Continuous middle cerebral artery FVm and electroencephalographic monitoring were performed in 45 patients during carotid endarterectomy. RESULTS: Clamped FVm was lowest in group 3 at 17+/-9 cm/s versus 36+/-16 and 33+/-11 cm/s for groups 1 and 2 (P<0.01). FVm values in groups 1 and 2 were similar. There was significant cerebral arterial vasodilation in group 3 patients on the basis of a pulsatility index of 0.38+/-0.15. The maximum FVm after clamp release was similar among the 3 groups. Normalized blood flow velocity 1 minute before release of the clamp was increased from the minimum flow velocity after clamping only in group 1 and 2 patients. CONCLUSIONS: The ipsilateral posterior communicating artery is a minor collateral pathway during acute carotid occlusion that contributes little to the collateral flow if there is a functional anterior communicating artery. Collateral flow through the middle cerebral artery is not recruited during occlusion in group 3 patients. The reperfusion FVm transient is independent of the primary collateral pathway. Documentation of functional collateral pathways on the basis of Doppler or angiographic examination may be advantageous in future studies since it can provide the basis for comparison among studies.

Arterial Occlusive Diseases↗
PubMed1998

A study of new fragrance mixtures.

OBJECTIVE: To determine the frequency of responses to four mixtures of fragrance materials in routine clinic patients undergoing patch testing for suspect allergic contact dermatitis. The validity of using fragrance mixtures alone, or in combination, was evaluated in terms of predicting allergy to fragrance judged on the basis of finding a response to at least one of the fragrance mixtures. METHODS: A total of 752 subjects were patch tested in five centers worldwide with (1) fragrance mix 8% (FM), (2) balsam of Peru 25%, (3) a mixture of seven of the eight FM 8% ingredients and other fragrance ingredients including jasmine absolute (jasmine/FM mix), and (4) a mixture of five selected natural fragrance ingredients (NM). RESULTS: Of 752 subjects, 100 (13%) had positive patch tests to at least one of the four fragrance mixtures. The age of the patients was 45.2 +/- 18.3 years (mean +/- SD). Ninety-six percent were Caucasian. Facial eruptions and hand involvement were the most common topographic sites. Of subjects exhibiting a positive response, 67% reacted to FM, 63% to the jasmine/FM mix, 47% to the NM, and 38% to balsam of Peru. Testing with FM and NM identified 84% of the perfume-allergic patients. FM 8% tested simultaneously with the jasmine/FM mix identified 86% of the perfume-allergic patients. Testing simultaneously with three test materials combining either the NM or the jasmine/FM mix with balsam of Peru and FM identified 95% of the perfume-sensitive patients. CONCLUSIONS: The simultaneous testing of NM or jasmine/FM mix, in addition to the conventional use of FM 8% and balsam of Peru, increases the sensitivity of testing for fragrance allergy from 81% to 95%.

Balsams↗
PubMed1997

Primary hyperoxaluria in an adult with renal failure, livedo reticularis, retinopathy, and peripheral neuropathy.

We present the case of a young woman who developed renal failure of unknown cause, and after 2 months of maintenance hemodialysis developed livedo reticularis, retinopathy, and peripheral sensory neuropathy. The patient was subsequently shown to have primary oxalosis type I, a rare autosomal recessive error of metabolism characterized by accumulation of calcium oxalate crystals in the kidneys, eyes, skin, and other organs. Intravascular obstruction, caused by deposition of calcium oxalate crystals in cutaneous arterioles, is thought to be responsible for the ischemic livedo reticularis lesions observed in this patient. A method is described for measuring serum glycolate by isotope dilution gas chromatography-mass spectrometry (GC-MS). An approach to the diagnosis and management is also briefly mentioned.

Adult↗
PubMed1996

Fragrance contact dermatitis: a worldwide multicenter investigation (Part I).

OBJECTIVE: The aim of this study was to determine the prevalence of responses to selected fragrance materials in patients with suspect fragrance allergy and to evaluate risk factors and associations with such responses. The validity of using specific fragrance ingredients versus a mixture of fragrances was evaluated in terms of predicting allergy to different fragrance ingredients. METHODS: One hundred sixty-seven subjects were evaluated in seven centers worldwide with a fragrance mix, the eight ingredients in the fragrance mixture, six other well-known fragrance allergens, balsam of Peru, and 15 lesser studied fragrance materials. RESULTS: The age of the patients was 44.9 +/- 17.5 years (mean +/- SD). More than 85% were women. A relatively high proportion gave a past history of atopic disease. Facial eruptions (40%) and hand involvement (26.7%) were the most common topographic sites. All but 4 of the 35 fragrance materials produced a positive response in > 1%. A reaction to fragrance mix occurred in 47.3%. Seven of the 34 ingredients tested produced an allergic response in more than 10% of those tested. Men were more likely than women to exhibit a positive response to five fragrance ingredients. White persons were more likely to react to perfume mix (52.8% versus 25.3%) and certain ingredients in the mix than Asian persons. Allergy to benzyl salicylate was more common in Japan than in Europe or the United States. CONCLUSION: The age at which patients with perfume allergy present for evaluation is similar to that of other contactants. Atopic individuals may be overrepresented in this group of patients. Face involvement is likely. White persons are more likely to react to fragrance mix, whereas in Asian patients benzyl salicylate was a more frequent allergen. Fragrance mix corrected with 85.6% of positive responses to fragrance ingredients. The addition of ylang ylang oil, narcissus oil, and sandalwood oil to fragrance mix would be expected to pick up 94.2% with positive responses to fragrance materials; adding balsam of Peru increases this to 96%.

Adult↗
PubMed1993

Different anisotropies for texture and grating stimuli in the visual map of cat striate cortex.

A comparison was made of the directional preferences of cat area 17 cells tested with two different stimuli, gratings and random-dot patterns. Depending on the stimulus, different distributions of direction preferences (anisotropies) were found in the same cells of the central representation of upper layers. With gratings most common preferred directions were vertical and horizontal. With textures, however, horizontal preferred directions were most common. In contrast, lower layer neurons had a bias for vertical preferred directions regardless of the type of stimulus used.

Animals↗
PubMed1991

Complementary global maps for orientation coding in upper and lower layers of the cat striate cortex and their possible functions.

Preferred stimulus orientations of striate cortical cells in the cat were analyzed for possible isotropic or anisotropic distributions. We separated the data twice, into central (0-5 degrees) vs. peripheral subgroups and into upper vs. lower layer cells. In the central group, absolute orientations were counted; in the periphery, a radial test was adopted by normalizing the preferred stimulus orientation of a cell to the line connecting the receptive field center to the retinal center. We found that in the center, vertical and horizontal orientations are overrepresented. In the periphery, the histograms show complementary anisotropies for upper and lower layers, favoring a map for radial orientation detection in upper layers and a more concentric map for orientation detection in lower layers. These results are possibly related to the probabilities of different optic flow fields on the retina under natural conditions of stimulation. They are discussed as possible neuronal structures supporting figure-ground discrimination, the distinction of self motion from object motion, and the location of objects in three-dimensional space.

Animals↗
PubMed1989

Iso- and cross-oriented columns in cat striate cortex: a study with simultaneous single- and multi-unit recordings.

The constancy of orientation tuning in vertical columns of the visual cortex of the cat was examined with conventional and newly developed multi-electrode methods. Preferred orientation was measured with single- and multi-unit recordings in 68 penetrations approximately perpendicular to the cortical layers and with inter-recording steps of only 40-70 microns. The tuning curves obtained revealed three types of penetration sequences: no-shift penetrations (37%), one-shift penetrations (41%) and double-shift penetrations (22%). Particular attention was paid to the orientation tuning at the transition zones below layer IV. The use of the multi-unit recording technique enabled the measurement of cross-oriented activity within a single electrode position mostly around the border between layers IV and V. Altering the type of anaesthesia (ventilation with room air or nitrous oxide-oxygen) produced only a quantitative change in the percentage of the encountered penetration types. The results suggest that upper and lower layers follow different principles of functional organization. As a consequence different types of columns, especially iso- and cross-oriented ones, are produced in a systematic way.

Animals↗
PubMed1988

Coherent oscillations: a mechanism of feature linking in the visual cortex? Multiple electrode and correlation analyses in the cat.

Primary visual coding can be characterized by the receptive field (RF) properties of single neurons. Subject of this paper is our search for a global, second coding step beyond the RF-concept that links related features in a visual scene. In recent models of visual coding, oscillatory activities have been proposed to constitute such linking signals. We tested the neurophysiological relevance of this hypothesis for the visual system. Single and multiple spikes as well as local field potentials were recorded simultaneously from several locations in the primary visual cortex (A17 and A18) using 7 or 19 individually advanceable fiber-microelectrodes (250 or 330 microns apart). Stimulus-evoked (SE)-resonances of 35-85 Hz were found in these three types of signals throughout the visual cortex when the primary coding channels were activated by their specific stimuli. Stimulus position, orientation, movement direction and velocity, ocularity and stationary flicker caused specific SE-resonances. Coherent SE-resonances were found at distant cortical positions when at least one of the primary coding properties was similar. Coherence was found 1) within a vertical cortex column, 2) between neighbouring hypercolumns, and 3) between two different cortical areas. We assume that the coherence of SE-resonances is mediated by recurrent excitatory intra- and inter-areal connections via phase locking between assemblies that represent the linking features of the actual visual scene. Visually related activities are, thus, transiently labelled by a temporal code that signalizes their momentary association.

Action Potentials↗