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Biomedical subjects

R Jürgens

Publications and source records attributed to R Jürgens.

At least 37 records · Page 2Linked to original sources
PubMed1989

Cerebral glucose metabolism in the course of subacute sclerosing panencephalitis.

Regional cerebral glucose metabolism was studied in a 15-year-old boy with subacute sclerosing panencephalitis before and after therapy with human interferon beta, using positron emission tomography of fluorine 18-2-fluoro-2-deoxyglucose. At first examination, metabolism was symmetrically decreased in the thalamus, cerebellum, and all cortical areas except prerolandic motor cortex, but increased in lentiform nucleus. A computed tomographic scan was normal. Six months later, bilateral focal necrosis centered in the previously hypermetabolic putamen was demonstrated by computed tomography and magnetic resonance imaging. The caudate nucleus and the superoposterior part of the putamen were spared, still showing increased metabolism. Corresponding with some clinical improvement, cortical glucose consumption rates had returned to a normal level.

Adolescent↗
PubMed1989

Interaction between cervico-ocular and vestibulo-ocular reflexes in normal adults.

The interaction of the cervico-ocular reflex (COR) and the vestibulo-ocular reflex (VOR) was studied in 20 human Subjects (Ss) during application of synergistic and antagonistic combinations of neck and vestibular stimuli, and during two different psychophysical tasks related to the Ss' self-motion sensation. Slow and quick eye movement responses were analyzed separately. Neck stimulation produced by horizontal rotation of the trunk about the stationary head elicited slow COR eye movements of very low gain; COR direction was anticompensatory, unlike the compensatory one of the VOR. During either a synergistic combination of neck and labyrinthine stimuli (head rotation on stationary trunk) or an antagonistic combination (head-to-trunk rotation counter to head-in-space rotation), the resulting slow eye movements were slightly larger than those during labyrinthine stimulation alone (whole body rotation). This weak neck contribution could be described by a directionally non-specific enhancement of VOR gain and a linear summation of VOR and COR slow phases. These effects were essentially independent of whether the Ss estimated the magnitude of their head turning or trunk turning in space. If Ss were estimating their trunk turning, neck stimulation also evoked quick eye movements, but these were small and hardly affected the VOR quick phases during the combined stimulations. In contrast, if Ss estimated their head turning, neck stimulation evoked large quick phases, which interfered with the quick phases of the VOR; during the synergistic combination of head and neck stimuli. COR quick phases added to those of the VOR, thereby shifting the gaze in the direction of head rotation (reorientation of gaze). With the antagonistic combination they subtracted, so that the VOR slow phase could compensate the head rotation in space (stabilization of gaze). These findings suggest that (1) the slow phase of the COR has no functional significance in intact humans and (2) the quick phase of the COR plays a role for both stabilization and reorientation of gaze depending on the behavioural context.

Adult↗
PubMed1988

Human immune response to group A streptococcal carbohydrate (A-CHO). III. Comparison of the efficiencies of anti-idiotopic antibody and of nominal antigen in the induction of IgM anti-A-CHO-producing B cells.

In this study the efficiencies of a monoclonal anti-idiotopic (Id) antibody (anti-Id498) and of various preparations of nominal antigen in the induction of an antigen-specific human B cell response in vitro were compared. Anti-Id498 recognizes a recurrent, binding site-related Id present on IgM antibodies with specificity for N-acetyl-D-glucosamine, the immunodominant group of streptococcal group A carbohydrate (A-CHO). We have previously shown that anti-Id498 induces IgM anti-A-CHO secretion from B cells of donors that possess Id-498+ antibodies in their serum. A-CHO was presented to B cells either in soluble or insoluble form, i.e. coupled to beads or as intact bacteria. Purified blood B cell populations from three Id+ healthy donors with high numbers of circulating anti-A-CHO B cells were used and antibody-producing B cells are enumerated in a single-cell assay (spot ELISA). The data show that anti-Id498 was superior in the induction of IgM anti-A-CHO-secreting B cells in two donors (factor 4.6 and 13.5 as compared to the most efficient antigenic stimulation). In the third donor antigen stimulation was slightly more efficient than anti-Id but only with Sepharose-bound A-CHO and not with soluble A-CHO or intact bacteria. The increase of specific B cells induced after stimulation with anti-Id498 could be abolished after addition of autologous T cells in two donors. On the contrary, an enhancement of the specific response was observed after addition of autologous T cells in antigen-stimulated cultures. Neither suppression nor enhancement were induced by addition of irradiated T cells.

Antibodies, Anti-Idiotypic↗
PubMed1988

Early involvement of the nervous system by human immune deficiency virus (HIV). A study of 79 patients.

We report on 79 patients of different stages of human immune deficiency virus (HIV) infection according to the Walter-Reed staging classification (WR). Comparing the HIV antibody content per weight IgG in serum and cerebrospinal fluid (CSF), 54 patients (68%) showed higher antibody activity in CSF than in serum, indicating intrathecal antibody production and thus a local challenge with the virus. The percentage of patients with these antibodies in CSF increased from stage WR 1 (33%) to WR 5 (90%). It decreased again in WR 6 (68%). Twenty-one patients with intrathecally produced antibodies but without evidence for opportunistic or preexistent neuropsychiatric diseases were further analyzed. Even in stages WR 1 and 2 these patients showed distinct clinical signs. These consisted mostly in apathic personality change (n = 13), peripheral neuropathy (n = 8) or mild hemisyndrome (n = 9). Progression to severe dementia solely caused by HIV encephalitis seems to be possible. More often acceleration of the mental disorder indicates a synergistic action of other pathogens. Our study gives further evidence for very frequent, early and clinically active involvement of the nervous system by the HIV infection.

Acquired Immunodeficiency Syndrome↗
PubMed1987

[The supinator syndrome. Study of the course in 20 patients and therapeutic recommendations].

Between 1972 and 1984, 20 cases of the supinator syndrome were examined with clinical and electrophysiological methods in our clinic. In 12 cases we found an idiopathic supinator syndrome in the strict sense and in 8 cases a traumatic lesion of the r. profundus of the radial nerve. We carried out follow-up studies in most of the patients. From these findings we attempt to derive guidelines for treatment. An absolute indication for operative revision in our opinion is present only in the case of complete transsection by trauma. Otherwise, the spontaneous course can be observed. The operative results in idiopathic cases are poor; it seems to be purposeless to operate patients who have a paresis for a long time. Therefore, the decision for or against an operative intervention has to be made soon after the diagnosis is secured.

Adolescent↗
PubMed1986

Locally synthesized antibodies in cerebrospinal fluid of patients with AIDS.

Twelve patients with AIDS were examined by enzyme-linked immunosorbent assay for antibody activity of IgG in serum and CSF. Two patients were only anti-HTLV III antibody carriers (stage I), two had lymphadenopathy syndrome (stage II) and eight had manifest AIDS (stage III). Eight of the 12 patients had 2- to 8-fold higher antibody titres in CSF than in serum, indicating that anti-HTLV III antibodies were produced in the nervous system. One of these patients with obviously locally synthesized anti-HTLV III antibodies in CSF belonged to stage I, two to stage II and five to stage III. Only four of these eight patients also showed locally synthesized IgG in CSF as measured by laser-nephelometry. In contrast, 61 controls with normal CSF (12), impaired blood-CSF barrier (12) multiple sclerosis (12) and various infections of the CNS other than HTLV III (25), the last two groups with locally synthesized IgG in CSF, all revealed negative results. It appears possible that locally synthesized anti-HTLV III antibodies in CSF are a sensitive and early indicator of an HTLV III infection of the nervous system.

Acquired Immunodeficiency Syndrome↗
PubMed1986

[Brain involvement in acquired immunodeficiency syndrome (AIDS): computed tomography (CT) and magnetic resonance tomography (MR)].

Involvement of the central nervous system in acquired immune deficiency syndrome (AIDS) is usually due to opportunistic infections; these frequently offer a difficult differential diagnostic problem. Imaging methods play an important part in the elucidation of symptoms. CT and MR findings were analysed in 13 patients with AIDS and neurological symptoms. Some infections of the central nervous system (encephalitis of unknown aetiology, cytomegalic encephalitis, meningitis) may show cerebral atrophy or even no morphological changes. Toxoplasmosis and PML are the most common opportunistic infections typical changes on CT and MR may lead to diagnosis. MR offers advantages compared with CT in its higher sensitivity for the demonstration even of small lesions.

Acquired Immunodeficiency Syndrome↗
PubMed1984

[Femoral nerve paralysis after vaginal hysterectomy. Its causes and forensic significance].

Paralysis of the femoral nerve following vaginal hysterectomy is a rare peripheral lesion the pathogenesis of which is still under dispute. However, after abdominal hysterectomy it is much more frequent, with a largely clarified aetiology. During 1975 to 1984 three clinically and electrodiagnostically established cases of paralysis of the n. femoralis following vaginal hysterectomy were seen; in one case, paralysis was bilateral. The question whether lesion of the n. femoralis is due to malpractice is still a moot point.

Adult↗
PubMed1983

Saccadic eye movements in psychiatric patients.

Saccadic eye movements were examined in 110 psychiatric patients and 26 controls, evaluating three parameters, the frequency of dysmetric saccades, nonfixation and the saccadic reaction time. Dysmetric saccades (dysmetria) were defined as saccadic reactions undershooting the target, nonfixation was defined as a deviation of the gaze from the target with the target stationary. While the nonfixation score and the saccadic reaction time were slightly increased in most of the psychiatric patient groups as compared to controls, an increase of the dysmetria score was confined to patients with schizophrenic and schizoaffective disorders. Dysmetria is thus interpreted as the expression of a relatively specific impairment of attention in these patients.

Adult↗
PubMed1982

Auditory evoked potentials to verbal stimuli in health, aphasic, and right hemisphere damaged subjects. Pathway effects and parallels to language processing and attention.

Acoustic evoked potentials to meaningful words were recorded in healthy, aphasic, and right hemisphere-damaged subjects under four conditions: monaural left and right, binaural, and dichotic stimulation. Four major findings emerged. First, healthy and brain-damaged subjects differed in amplitude and latency values of the N1 and P2 components. In healthy subjects N1 was greater and P2 smaller than in aphasics. Both components peaked earlier inpatients than in normals. Second, evoked potentials of healthy subjects showed a late sustained component which was decreased in aphasics. Third, the latencies of P1 and N1 as well as the amplitude of N1 showed a "pathway effect", i.e. shorter latency and greater amplitude to contralateral stimulation. Fourth, under the dichotic condition, P1 and N1 peaked earlier over the left hemisphere. The N1 amplitude behaved differently in the three groups depending upon stimulating conditions. It is suggested that these differences reflect linguistic coding and related attentional processes in patients and normals.

Adult↗
PubMed1982

Disturbed smooth pursuit and saccadic eye movements in schizophrenia.

Smooth pursuit and saccadic eye movements of schizophrenic patients were examined. In a pendulum (0.5 Hz) tracking task schizophrenic inpatients had a slightly lower smooth pursuit gain than outpatients and controls, who showed no significant differences. The number of saccades, counter-saccades and velocity arrests occurring in a 20 s tracking epoque was the same in patients and controls, but patients made larger saccades. When tracking a stepping target by saccadic eye movements, schizophrenic inpatients, and to a lesser extent outpatients, exhibited longer reaction times than controls and had a higher incidence of "non-fixation" (saccades away from the target while the target is stationary). Schizophrenic patients also showed a significantly larger proportion of dysmetric saccades (undershooting the target). While similar changes of reaction time and non-fixation score were observed in manic-depressives and alcoholics, dysmetria was more often found in schizophrenics and possibly constitutes the expression of a specific impairment of attention.

Adolescent↗
PubMed1981

Natural and drug-induced variations of velocity and duration of human saccadic eye movements: evidence for a control of the neural pulse generator by local feedback.

The present report considers goal directed human saccadic eye movements. It addresses the question how a given perceived target excentricity is transformed into the innervation pattern that creates the saccade to the target. More specifically, it investigates whether this pattern is an appropriately selected preprogram or whether it is continuously controlled by a local feedback loop that compares a non-visual eye position signal to the perceived target excentricity (a visual signal would be too slow). To this end, the relation between the accuracy of saccades aimed at a given target and their velocity and duration was examined. Duration and velocity were found to vary by as much as 60% while the amplitude showed no related variation and had an almost constant accuracy of about 90%. By administrating diazepam, the variabiity of saccade duration and velocity could be further increased, but still the amplitude remained almost constant. These results favour the hypothesis that saccadic innervation is controlled by a local feedback loop.

Administration, Oral↗
PubMed1981

Different effects involved in the interaction of saccades and the vestibulo-ocular reflex.

The accuracy of human goal-directed saccades during passive sinusoidal whole-body rotation is the same as that of normal saccades with the head still. Two mechanisms contribute to this accuracy: 1. There is an incomplete summation (70% on the average) of saccade and VOR velocities. 2. The duration of saccades during head rotation is lengthened if VOR and saccade velocities have the same direction, and is shortened if their direction is opposite. The latter finding supports the hypothesis that saccades are controlled by local feedback.

Eye Movements↗
PubMed1980

Somatosensory-evoked potentials and perception of skin velocity.

Mechanical ramp indentations of constant amplitude and randomized velocities to the finger tip of human subjects were used to adequately stimulate the rapidly adapting Meissner corpuscles. The somatosensory-evoked potentials and the subjects' estimations were simultaneously recorded and analyzed off-line. The magnitude of perception showed a nonlinear, monotone-rising function approximated by a log or power function with respect to ramp velocity. The small, early components of the EP showed little correlation to stimulus velocity. The large, late components (120 ms or more) showed a stimulus response function similar to the psychophysical one. These large, late components resemble the alpha rhythm in frequency and distribution. It is concluded that although the large, late component of the EP show a similar relation to the psychophysical one, it is unlikely that there is a specific correlation between them.

Adolescent↗