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Biomedical subjects

M Berg

Publications and source records attributed to M Berg.

At least 127 records · Page 7Linked to original sources
PubMed1996

Periventricular heterotopia: an X-linked dominant epilepsy locus causing aberrant cerebral cortical development.

Periventricular heterotopia (PH) involves dramatic malformations of the human cerebral cortex. Here we show that PH is closely linked to markers in distal Xq28 (maximal two-point lod score = 4.77 for F8C at theta = 0; maximal multipoint lod score = 5.37), so that affected females are obligatory mosaics for the mutation; that PH is lethal to at least some affected males; that PH malformations consist of well-differentiated cortical neurons filling the adult subependymal zone; and that individuals with PH are at high risk for epilepsy, though they have no other neurological or external stigmata. The PH gene may represent an important epilepsy susceptibility locus in addition to playing a key role in normal cortical development.

Abortion, Habitual↗
PubMed1996

A cognitive-behavioral treatment of patients suffering from "electric hypersensitivity". Subjective effects and reactions in a double-blind provocation study.

This study tested psychological treatment of patients with "electric hypersensitivity." Seventeen patients were randomly assigned to a treatment group or a waiting-list control group in a pretest-posttest control group design. The patients were also taking part in double-blind provocation tests before and after the treatment. Subjective ratings of symptoms were registered and blood samples were taken and analyzed for "stress-related" variables, such as prolactin, cortisol, dehydroepiandrosterone, and cholesterol levels. The patients in the experimental group reduced their evaluations of the disability more than the control group did. This indicates that psychological treatment may be of value in this disease. However, none of the psychophysiological measures or the subjective reactions to the provocation test showed any significant between-group difference. The conclusion from the provocation test is that this group of alleged hypersensitive patients did not react to the electromagnetic fields.

Adult↗
PubMed1996

Melatonin and adrenocorticotropic hormone levels in video display unit workers during work and leisure.

This study examined 47 office workers during a day of regular work in front of a video display unit (VDU) and a day of leisure in the same environment. The study investigated possible effects of VDU work on circulating melatonin and adrenocorticotropic hormone (ACTH) levels. Circulating melatonin levels decreased significantly during VDU work, whereas ACTH levels increased significantly. In contrast, melatonin and ACTh levels did not change significantly during a day of leisure. Mental strain during work was significantly and positively associated with circulating levels of ACTH but not melatonin. The results indicate that the VDU environment is associated with measurable changes in melatonin and ACTH levels. Mental strain might explain changes in ACTH levels, but specific factors that might contribute to changes in melatonin levels are unknown. These findings might be relevant to the recent debate about the possible influence that electromagnetic and VDU environments might have on electromagnetic sensitivity.

Adrenocorticotropic Hormone↗
PubMed1995

Kainic acid-induced seizures and brain damage in the rat: role of calcium homeostasis.

Seizure activity induced by kainic acid (KA) and subsequent neuronal death are thought to be associated with an increase in cytoplasmic free calcium ([Ca2+]i) and can be prevented by N-methyl-D-aspartate (NMDA) antagonists. In addition to influx through receptor operated Ca2+ channels the increase in [Ca2+]i may be the result of an increased influx through voltage-operated calcium channels and/or release from intracellular deposits. It was therefore investigated whether compounds other than NMDA antagonists with known actions on the intracellular Ca2+ homeostasis had any protective effect against KA-induced neuronal death. Voltage-operated calcium channels in the cell membrane were blocked with the L-type ion channel antagonist, Nimodipine (1.0 mg/kg), and release of Ca2+ from internal stores was prevented with Dantrolene (10 mg/kg). Animals from two control groups injected with kainate (8 mg/kg) exhibited a survival rate of 67 and 53%, respectively. Countings of neurons in dorsal hippocampus showed subtotal or total loss in the CA1 and CA3 subregions. There were no significant differences concerning seizure and survival rates in the groups injected with kainate and treated with Dantrolene or Nimodipine and the control groups. The group treated with Dantrolene showed no neuropathological changes in the hippocampal CA3 region and only slight changes in the Ca1 region, while the neuron loss in the Nimodipine group did not differ from that of its control group. The results emphasize the importance of Dantrolene-sensitive Ca2+ release from intracellular stores for the development of seizure-induced neuronal death.

Animals↗
PubMed1995

A nonconventional approach to the treatment of "environmental illness".

Twenty patients with symptoms of "environmental illness" were subject to a controlled study of deep versus superficial acupuncture. The patients were evaluated by a detailed questionnaire concerning their occupational, environmental, and medical history. Blood samples were taken as well. Patients were randomized to deep or superficial acupuncture. Both groups improved significantly in key variables during and after treatment. There were no group differences. There were no changes in biological variables apart from a gradual and continuous increase in serum cortisol and a decrease in neuropeptide Y, which was somewhat more accentuated in those receiving deep acupuncture. This rise in cortisol may have contributed to decreased dermal symptoms among the participants. It is hypothesized that the positive treatment results observed are partly due to weakening of the conditioned response, linking bodily symptoms to environmental agents. To date, a number of different methods have been tried in the management of patients with environmental illness. However, only rarely have the treatments been evaluated in controlled studies.

Acupuncture Therapy↗
PubMed1995

Regulation of the segmental swim-generating system by a pair of identified interneurons in the leech head ganglion.

1. The aim of this study was to identify neurons that modulate activity of segmental swim gating interneurons. We found a pair of bilaterally symmetrical interneurons, cells SE1, whose activity level directly influences three groups of segmental neurons associated with generating swimming in the medicinal leech. 2. The somata of cells SE1 are located on the dorsal surface of the subesophageal ganglion. Their axons extend most, if not the entire, length of the ventral nerve cord and appear to make identical connections with the same group of swim-generating neurons in all segmental ganglia. 3. Cells SE1 excite monosynaptically all segmental swim gating interneurons, cells 204, examined. The level of excitation in cell 204 is directly correlated with the firing frequency of cell SE1. In most quiescent preparations (when the preparation is not swimming) hyperpolarization of a single cell SE1 eliminates all excitatory synaptic input to cells 204. 4. Cells SE1 excite monosynaptically three swim oscillatory interneurons, cells 115, 28, and 208. The strength of the connection from cell SE1 to cell 115 is stronger than the connection from cell SE1 to either cells 28 or 208. The level of excitation in cell 115 is directly correlated with the firing frequency of cell SE1. In most quiescent preparations, hyperpolarization of a single cell SE1 eliminates all excitatory synaptic input to cell 115 but has only a minor effect on the level of activity in cells 208 and 28. 5. Due most likely to the strong and direct connections cells SE1 have with swim gating and oscillatory interneurons, brief stimulation of cell SE1 can elicit swimming. Swimming generally occurs within 1 s after stimulation of cell SE1. During swimming, the membrane potential of cell SE1 depolarizes by 2-5 mV, and its firing frequency increases. Brief depolarization of cell SE1 during swimming reliably shifts the phase of the swimming rhythm, whereas longer periods of depolarization increase both swim period and burst duration. 6. Excitatory motor neurons to the dorsal longitudinal muscles, cells 3, 5, and 7, are strongly excited by stimulation of cell SE1. The firing frequency of cell 3 is positively correlated with the firing frequency of cell SE1. 7. The results of this study indicate that cells SE1 can modulate the level of excitation in three groups of neurons associated with generating leech swimming.(ABSTRACT TRUNCATED AT 400 WORDS)

Action Potentials↗
PubMed1995

Missense mutation in exon 7 of the common gamma chain gene causes a moderate form of X-linked combined immunodeficiency.

Clinical and immunologic features of a recently recognized X-linked combined immunodeficiency disease (XCID) suggested that XCID and X-linked severe combined immunodeficiency (XSCID) might arise from different genetic defects. The recent discovery of mutations in the common gamma chain (gamma c) gene, a constituent of several cytokine receptors, in XSCID provided an opportunity to test directly whether a previously unrecognized mutation in this same gene was responsible for XCID. The status of X chromosome inactivation in blood leukocytes from obligate carriers of XCID was determined from the polymorphic, short tandem repeats (CAG), in the androgen receptor gene, which also contains a methylation-sensitive HpaII site. As in XSCID, X-chromosome inactivation in obligate carriers of XCID was nonrandom in T and B lymphocytes. In addition, X chromosome inactivation in PMNs was variable. Findings from this analysis prompted sequencing of the gamma c gene in this pedigree. A missense mutation in the region coding for the cytoplasmic portion of the gamma c gene was found in three affected males but not in a normal brother. Therefore, this point mutation in the gamma c gene leads to a less severe degree of deficiency in cellular and humoral immunity than that seen in XSCID.

Amino Acid Sequence↗
PubMed1995

Turning a practice into a science: reconceptualizing postwar medical practice.

In recent years, many editorials in leading North American medical journals have argued that medical practice is seriously flawed. Ofter, decision-support techniques are mentioned as a potential solution to this problem. I argue that these recent calls embody a specific reconceptualization of medical practice and its problems. Within the postwar medical literature, divergent discourses on the virtues and troubles of postwar medical practice can be found. Through a focus on medical editorials, I demonstrate the existence of several different notions of the 'scientific nature' of medical action. Comparing the more recent of these images to those dominating earlier medical journals, one main shift is apparent. While, earlier, medical action was often described as an artful application of scientific knowledge, only mildly tainted by external, social problems, recent conceptualizations often locate both the scientific nature of medicine and the causes of its problems in the physician's brain. Even within this new discourse, however, scientific rationality does not always speak with the same voice, as reflected in the existence of different decision-support techniques. I argue that these different techniques, which are presented as solutions to the flaws of medical practice, lay at the root of the development of the cognitivist image(s) in the first place.

History, 20th Century↗
PubMed1995

Facial nerve involvement in patients with acoustic neurinomas. Examination with magnetic single- and bi-stimulation.

The diagnosis of acoustic neurinomas is usually made by auditory and vestibular testing and magnetic resonance imaging. As clinical involvement of the facial nerve is infrequent, occurring only in large tumours, only little is known about the subclinical involvement of the facial nerve. Transcranial magnetic stimulation of the VIIth cranial nerve in the temporal bone, adjacent to acoustic neurinoma growth, seems to be an adequate instrument for electrophysiological measurements of minimal nerve lesions without clinically obvious facial palsy. In 70% out of 97 patients with surgically and histologically confirmed acoustic neurinomas, obvious elongation of the intratemporal conduction time of the facial nerve was found. This affection was dependent on tumour size. No correlation was found to preoperative or postoperative facial nerve function and hearing function. The latencies of the conduction time showed a tendential increase in patients with a more difficult grade of surgery and of facial nerve preparation due to fibrous adhesions and nerve spreading on the tumour capsule. A completely new stimulation modality, the application of two magnetic stimuli in quick succession, was applied for the first time in acoustic neurinoma patients, and revealed facial nerve involvement by acoustic neurinoma growth. Facial nerve involvement in acoustic neurinoma can be detected by transcranial magnetic stimulation even in patients with small and medium sized tumours but with clinically normal facial function.

Cranial Nerve Neoplasms↗
PubMed1995

Clinical survey of Meniére's disease: 574 cases.

Only 27% out of 574 patients suffering from Meniére's disease initially started with the typical Meniére's triad. A great advantage in order to diagnose Meniére's disease can be established with the telemetric-ENG. With this equipment it is possible to verify a nystagmus outside the clinic (at home, at work) at any time in patients suffering from vertigo attacks. Most of our patients showed an omnifrequent sensorineural hearing loss on the affected side. Many of our patients with Meniére's disease suffered from internal diseases (e.g. hypotonia, hyperlipidemia, diabetes mellitus), allergy or an affection of the paranasal sinuses, which may constitute co-factors triggering Meniére's disease.

Adolescent↗
PubMed1995

[What should be recommended to a patient with a small radiologically suspected acoustic neuroma?].

OBJECTIVE: Criteria for therapeutic decision-making for intrameatal acoustic neurinomas that are suspected radiologically. DESIGN: Retrospective evaluation. PATIENTS: 114 surgically treated patients of the ORL Dept. of the University Erlangen-Nuremberg. OUTCOME MEASURES: Rate of complications. Preservation of facial nerve function and hearing. Preoperative time course of hearing. Reliability of radiological examination. Progression of symptoms and tumor growth. THERAPY: Surgical exposure and complete removal by the enlarged middle cranial fossa approach. RESULTS: In 47% of cases surgery confirmed a neurinoma limited to the internal auditory meatus. In 41%, tumors were larger than expected and had protruded into the cerebellopontine angle, indicating preoperative tumor growth during an average period of 5.4 months before surgery could be completed. The remaining 12% of patients were found to have a facial neurinoma, meningioma or non-tumorous lesion of the internal auditory canal. No permanent neurological deficits or fatalities occurred in any of the patients treated. Facial function was favorable in 88% and moderate pareses or synkineses occurred in 12%. The degree of hearing preservation depended on the preoperative situation. When the preoperative pure-tone average (at 0.5, 1, 2 and 4 kHz) was 30 dB or less, hearing levels of less than 90 dB could be preserved in 70% of cases. Findings also demonstrated that the complication rate and success of function preservation were similar to younger patients in patients older than 60 years (n = 21). Without surgery auditory acuity decreased by 10 dB per year. The volume of intrameatal neurinomas in 7/10 cases followed by MRI doubled during a median following time of 32 months. CONCLUSIONS: Acoustic neurinoma surgery by the enlarged middle cranial fossa approach is a safe procedure with low complication rates. The percentages of preservation of facial function and hearing can be excellent in cases with small tumors and good preoperative hearing. To date no parameter has been found to predict tumor growth or the time course for hearing loss in individual cases. Surgical ablation of radiologically suspected, small acoustic neurinoma by the transtemporal approach is recommended.

Adolescent↗
PubMed1994

Interaction of IL-2R beta and gamma c chains with Jak1 and Jak3: implications for XSCID and XCID.

Interleukin-2 (IL-2) signaling requires the dimerization of the IL-2 receptor beta.(IL-2R beta) and common gamma (gamma c) chains. Mutations of gamma c can result in X-linked severe combined immunodeficiency (XSCID). IL-2, IL-4, IL-7 (whose receptors are known to contain gamma c), and IL-9 (whose receptor is shown here to contain gamma c) induced the tyrosine phosphorylation and activation of the Janus family tyrosine kinases Jak1 and Jak3. Jak1 and Jak3 associated with IL-2R beta and gamma c, respectively; IL-2 induced Jak3-IL-2R beta and increased Jak3-gamma c associations. Truncations of gamma c, and a gamma c, point mutation causing moderate X-linked combined immunodeficiency (XCID), decreased gamma c-Jak3 association. Thus, gamma c mutations in at least some XSCID and XCID patients prevent normal Jak3 activation, suggesting that mutations of Jak3 may result in an XSCID-like phenotype.

Animals↗
PubMed1994

Turing's game and the clinical significance of outcome with borderline patients at a day hospital.

Clinical significance of a treatment effect is indicated when a treated patient, after discharge, cannot be distinguished clinically from a person who is functioning on some criterion level in terms of adjustment and normality. This principle is demonstrated in a questionnaire follow-up of patients at a day hospital. Defining the criterion level, a sex- and age-matched nonpatient group completed the same questionnaire. On the basis of the questionnaires, four judges independently guessed whether or not each respondent was an ex-patient. The agreement among the judges was high, and their classification agreed with that of a discriminant analysis in eventually declaring approximately 25% of the patients to be nonpatients. A simple model was proposed to account for the judges' performance.

Analysis of Variance↗