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Biomedical subjects

W Lang

Publications and source records attributed to W Lang.

At least 253 records · Page 14Linked to original sources
PubMed1988

Cortical slow potentials in verbal and spatial tasks--the effect of material, visual hemifield and performing hand.

Fifteen right-handed students voluntarily initiated the tachistoscopic presentation of visual stimuli containing either verbal (abstract words) or spatial (stereogeometric figures) material. Subjects had to reproduce stimulus material which had been presented either in their right or their left hemifield of vision by writing or drawing, either with their right or their left hand. Material-specific effects were found during the reproduction period: amplitudes of the performance-related negative potential shifts were larger in parietal and occipital recordings (P4, O1, and O2) when drawing as compared to writing. The opposite was true in frontal and left central leads (F3, F4, and C3) where writing was associated with larger negative amplitudes than drawing. Although subjects were informed about the nature of the forthcoming stimulus before voluntarily initiating the task, material-specific effects were missing in the preparation period. The performing hand had an influence on potentials in central leads, whereas hemifield of vision had no effect on preparation- and performance-related slow potential shifts.

Adolescent↗
PubMed1988

Occult carcinomas of the thyroid. Evaluation of 1,020 sequential autopsies.

In a sequence of 1,020 autopsies, all thyroid glands were thoroughly examined during a two-year period. Fifty-seven percent of the thyroid glands had no gross or histologic changes; approximately 22% were more or less goitrous. In 63 of 1,020 (6.2%) thyroid glands, a clinically latent carcinoma was detected. The greatest diameter of tumors measured microscopically ranged between 0.5 and 10.5 mm. Sixty-nine percent of the carcinomas were found by excision of a local change of tissue visible through close examination by the naked eye. All but one carcinoma were of papillary type, the one exception being a C-cell carcinoma. Multicentricity was found in 46% and regional lymph node metastases in 14%. There was no significant predilection of sex or age. It was concluded that these tumors have no propensity to increase to a clinically apparent thyroid disease.

Adenoma↗
PubMed1988

Pharmacokinetics of 14C-labelled rhein in rats.

After oral or intravenous administration of 14C-rhein to male rats, blood concentrations were measured for up to 48 h. Both mean blood level curves and also the calculated pharmacokinetic constants show a fairly good conformity. Organ distribution was measured up to 2 days after intravenous and up to 7 days after oral application. In most organs the activity is lower than in plasma with very low values in testicles and in brain. Higher values are found in the main excretion organ, the kidney. The plasma protein binding of 14C-rhein is very high both in rat and human serum. Absorption in or adsorption on erythrocytes is very small. Rhein and its metabolites are excreted by kidney and liver. Biliary-excreted rhein metabolites are easily reabsorbed and finally excreted with urine. In bile, there are mainly two conjugated metabolites of rhein, whereas in urine also larger amounts of rhein and one or two additional metabolites can be detected. All metabolites seem to be conjugates, because they can be split by glucuronidase/arylsulfatase to rhein. Rhein is absorbed after oral application by about 50-60% and after administration into the colon by about 50%.

Animals↗
PubMed1988

Event-related EEG-spectra in a concept formation task.

Event-related spectra of short EEG epochs were investigated in a concept formation paradigm. In this task, subjects had to learn to transform letters into Morse codes. Related to a resting state, cognitive performance in this learning task was characterized (i) by an increased mean power density (MPD) within the Theta frequency band (theta) in recordings over the frontal lobes and (ii) by a reduced Alpha (alpha) MPD in all recording sites. The performance-related increase of the theta-MPD, as obtained in left frontolateral and frontomedial recordings, separated (i) the learning task from an appropriate control and (ii) a group of successful learners from a group which performed less efficiently. MPDs of the alpha- and the delta-(Delta) frequency band did not differ between tasks and groups. A consistent finding in the learning tasks was a temporal dissociation of performance-related alpha-attenuation between parietal and frontal recordings: in the period preceding the presentation of the informative stimuli, the alpha-rhythm is attenuated especially at parietal recordings, whereas in frontal recordings, alpha-attenuation accompanied information processing and response selection.

Adult↗
PubMed1987

Distribution and biochemical characterization of somatostatin receptors in tumors of the human central nervous system.

Fifty-two brain tumors, consisting of 17 astrocytomas, 4 oligodendrogliomas, 20 glioblastomas, 3 neurinomas, 2 ependymomas, 1 neurofibroma, 1 ganglioneuroblastoma, 1 medulloblastoma, 1 plexus papilloma, 1 teratoma, and 1 germinoma, were tested for their content of specific somatostatin receptors using autoradiographic techniques or in vitro binding assays with membrane homogenates. Somatostatin receptors were found in most of the differentiated glia-derived tumors such as astrocytomas and oligodendrogliomas whereas the poorly differentiated glioblastomas were usually free of receptors. Tumors originating from neuroblasts, i.e., ganglioneuroblastoma and medulloblastoma, contained a high density of somatostatin receptors, whereas neurinomas and neurofibromas as well as the ependymomas, one teratoma, and one plexus papilloma were lacking such receptors. In one germinoma, low amounts of somatostatin receptors were observed over the lymphocytic elements. Receptor-positive tumors had saturable and high affinity receptors with pharmacological specificity for somatostatin and somatostatin analogues resembling that of normal human central nervous system tissue. In most instances, they could be labeled with two different iodinated radioligands, a somatostatin octapeptide derivative (204-090) or a somatostatin-28 analogue. This is the first time that somatostatin receptors have been shown to exist not only on neuronal structures of the central nervous system but also on glial elements. The precise function of such somatostatin receptors on glial cells, which may be different from neurotransmission, remains to be determined.

Adolescent↗
PubMed1987

Comparison of binding sites for the calcitonin gene-related peptides I and II in man.

Specific and saturable binding sites of the synthetic human calcitonin gene-related peptide-I (CGRP-I) and -II (CGRP-II) have been identified in membrane homogenates of the human central nervous system, heart and spleen. Half maximal inhibition of the binding of 125I-CGRP-II was achieved with 0.25 nM and 1.7 nM of non-radioactive CGRP-I or -II, and with 260 and 850 nM salmon calcitonin in the spinal cord and cerebellum, respectively, but 1 microM human calcitonin was not recognized. Autoradiographs of diencephalic sections revealed different distribution of 125I-CGRP-I and -II binding sites.

Autoradiography↗
PubMed1987

Clinical, immunologic, and serologic findings in men at risk for acquired immunodeficiency syndrome. The San Francisco Men's Health Study.

Forty-nine percent of homosexual/bisexual men were positive for antibody to the human immunodeficiency virus (HIV) in a population-based probability sample of 1034 single men recruited from San Francisco. All heterosexual men were negative. Among seropositive men, marked lymphadenopathy was present in 29%, and 16% had at least two other symptoms or signs suggestive of HIV infection. However, lymphadenopathy alone failed to indicate severity of immune impairment. The occurrence of two or more clinical signs and symptoms, except for marked lymphadenopathy, correlated with HIV infection, diminished skin test reactivity, and reduction in Leu 3a T cells. Twenty-nine percent of seropositive men had fewer than 400 absolute Leu 3a T helper cells per microliter (less than 0.4 X 10(9)/L). Seronegative homosexual/bisexual men did not differ from heterosexual men in any clinical or laboratory variables except for increased numbers of suppressor Leu 2a T suppressor cells per microliter.

Acquired Immunodeficiency Syndrome↗
PubMed1987

Sexual practices and risk of infection by the human immunodeficiency virus. The San Francisco Men's Health Study.

The San Francisco Men's Health Study is a prospective study of the epidemiology and natural history of the acquired immunodeficiency syndrome in a cohort of 1034 single men, 25 to 54 years of age, recruited by multistage probability sampling. At entry, June 1984 through January 1985, the seropositivity rate for human immunodeficiency virus (HIV) infection among homosexual/bisexual study participants was 48.5%. No heterosexual participants were HIV seropositive. Among homosexual/bisexual men reporting no male sexual partners in the two years before entry into the study, seropositivity was 17.6%. For those reporting more than 50 partners, seropositivity was 70.8%. Only receptive anal/genital contact had a significantly elevated risk of HIV infection. Douching was the only ancillary sexual practice that contributed significantly to risk of infection.

Acquired Immunodeficiency Syndrome↗
PubMed1987

Computed tomography in Hallervorden-Spatz disease.

We report computed tomography (CT) findings of an autopsy-proven case of late-infantile Hallervorden-Spatz disease (HSD). The patient's symptoms started in preschool age with dystonic posture, leading shortly to complete loss of verbal communication and ambulation with marked torsion dystonia. She died aged 23 years. Cranial CT, performed at the age of 18 years, showed moderate infratentorial atrophy, but cortical cerebral atrophy, ventricular enlargement and caudate atrophy were all absent; there were symmetrical areas of increased density in the globus pallidus, and ironstaining pigment deposits at this site were confirmed post mortem. In the appropriate clinical setting such CT findings may be diagnostically helpful in the late-infantile form of HSD. However, experience with CT as well as with magnetic resonance imaging in HSD is still very limited.

Adult↗
PubMed1987

Bereitschaftspotential in patients with unilateral lesions of the supplementary motor area.

In the present study, an attempt was made to examine the sensitivity of the Bereitschaftspotential (BP) preceding simple finger movement in revealing pathophysiological patterns of premovement cortical activity in patients with chronic unilateral lesions of the supplementary motor area (SMA). Usually, in healthy subjects, BP has a clear maximum in Cz with larger amplitudes than in Ccon (located over the motor cortex, contralateral to the performing hand). In the patients, amplitudes did not differ between Cz and Ccon. This effect of the lesion on BP topography, was found in movements of either side. However, intraindividual comparisons revealed that the reduction of the BP in Cz (relative to Ccon) was larger for movements contralateral to the SMA lesion than for those ipsilateral of it.

Brain Diseases↗
PubMed1987

The San Francisco Men's Health Study: III. Reduction in human immunodeficiency virus transmission among homosexual/bisexual men, 1982-86.

The prevalence and incidence of infection by the human immunodeficiency virus (HIV) has been under study in a cohort of 1,034 single men recruited by area probability sampling from a six kilometer square area of San Francisco where the epidemic of acquired immunodeficiency syndrome (AIDS) has been most severe. Prevalence of infection among homosexual/bisexual study subjects increased from an estimated 22.8 per cent during the last half of 1982 to 48.6 per cent during the period July through December 1984. During three subsequent six-month periods, prevalence remained stable at approximately 50 per cent. Annual infection rates, measured by seroconversion among seronegative study subjects, decreased from an estimated 18.4 per cent per year from 1982 to 1984, to 5.4 and 3.1 per cent during the first and second halves of 1985, and to 4.2 per cent during the first six months of 1986. These declines were associated with reductions of 60 per cent or more in the prevalence of high-risk sexual practices associated with both acquiring and disseminating infection by the human immunodeficiency virus.

Acquired Immunodeficiency Syndrome↗
PubMed1987

Slow negative potential shifts indicating verbal cognitive learning in a concept formation task.

It is well-known clinically that patients with left frontal lesions are impaired in their verbal-cognitive learning ability. Starting from such observations, it is of particular interest whether the event-related cerebral potential shifts recorded in healthy human subjects would indicate a left frontal lobe involvement in verbal-cognitive learning tasks. In a concept formation paradigm, subjects learned by trial and error to transform letters into Morse codes. This cognitive performance was accompanied by a slow negative potential shift (SP) that in frontal recordings was lateralized towards the left hemisphere. off results show in a later stage of learning, in which the experience of the preceding trial and error learning could be integrated, an increasing slow negativity over the frontal cortex. Ss also participated in a control task with already known letter/Morse code combinations. Again, a negative potential shift occurred within the stimulus-response interval, however, it was smaller in amplitude.

Adult↗