Search PubMed⌕ Search

Biomedical subjects

R Ochs

Publications and source records attributed to R Ochs.

At least 19 recordsLinked to original sources
PubMed2002

Driving current through single organic molecules.

We investigate electronic transport through two types of conjugated molecules. Mechanically controlled break junctions are used to couple thiol end groups of single molecules to two gold electrodes. Current-voltage characteristics ( IVs) of the metal-molecule-metal system are observed. These IVs reproduce the spatial symmetry of the molecules with respect to the direction of current flow. We hereby unambiguously detect an intrinsic property of the molecule and are able to distinguish the influence of both the molecule and the contact to the metal electrodes on the transport properties of the compound system.

Journal Article↗
PubMed2000

New high-DQE imaging plate scanner using the reflected readout laser signal for noise corrections.

Imaging Plates (IPs) are in principle ideal electron detectors combining a large active layer area with a high sensitivity, linear dynamic range detection over 5 orders of magnitude. A moderate resolution and a decreasing detection quantum efficiency (DQE) for higher electron doses limit their use so far. The decrease of the DQE results from linear noise contributed by readout laser instabilities and inhomogeneities of the IP active layer. Here we present data on a new IP drum scanner prototype. This scanner combines twin channel amplification electronics with a new type of readout laser which allows a smaller readout focus and increased stability. The current nominal pixel size is 25 microm, and the measured modulation transfer function (MTF) indicates that further reduction of the scanning step size down to pixel sizes in the range of 12-15 microm should be possible. A unique feature of the new scanner is the simultaneous recording of the reflected readout laser light. The reflected light signal can be used for a posteriori alignment of repeated scans of one individual IP and for a correction of one part of the high spatial frequency noise contribution (reflected light correction). The posteriori alignment now allows an easy conventional gain normalization of the luminescence signal without using special markers on the IP. Both corrections lead to an increase of the DQE for high electron doses.

Biophysical Phenomena↗
PubMed1994

Further studies on satellite nucleoli of lymphocytes in patients suffering from B chronic lymphocytic leukaemia.

Satellite nucleoli were studied in lymphocytes of patients suffering from various stages of B chronic lymphocytic leukaemia without and after treatment with cytostatic monotherapy with chlorambucil. The percentage of lymphocytes with satellite nucleoli in the peripheral blood of investigated patients was very constant and showed only a statistically non-significant slight trend to decrease in the most advanced stage of the disease. In contrast, the count of these cells increased in advanced stages of the disease, and decreased after the cytostatic chemotherapy. From the methodological point of view, satellite nucleoli may be easily visualized by means of a simple staining for RNA with acidified basic dyes without fixation. Such staining provided similar results as cytochemical immunoreactions for the characteristic nucleolar protein B23.

Cell Nucleolus↗
PubMed1993

Cytochemistry of satellite nucleoli in human lymphocytes.

Satellite nucleoli of lymphocytes were studied to provide additional information on the cytochemistry of these nucleoli particularly with respect to the presence of rDNA and RNA polymerase I. According to the results of the in situ hybridization satellite nucleoli contain rDNA similarly as characteristic nucleoli. Immunostaining demonstrated that satellite nucleoli similarly as characteristic nucleoli possess RNA polymerase I in addition to proteins B23, C23 and fibrillarin. RNA of satellite nucleoli was detected in satellite as well as in characteristic nucleoli with buffered toluidine or methylene blue. The cytochemical evidence and morphology of satellite nucleoli strongly supports the supposition that these nucleoli represent solitary small nucleoli containing nucleolus organizer regions which did not participate in the formation of characteristic nucleoli.

Cell Nucleolus↗
PubMed1991

A comparative study of alpidem, a nonbenzodiazepine, and lorazepam in patients with nonpsychotic anxiety.

The use of benzodiazepines for generalized anxiety disorder (GAD) is a safe and effective treatment; however, their potential to produce dependence and impair psychomotor and cognitive functions is a drawback. In this study the efficacy and safety of alpidem, a nonbenzodiazepine, was assessed. Thirty patients who met DSM-III-R criteria for GAD were randomized to either alpidem (225 mg), lorazepam (4.5 mg), or placebo. The primary efficacy measure was the Hamilton Rating Scale for Anxiety (HAM-A). A repeated measures multivariate analysis of variance (MANOVA) was used to determine differences in HAM-A scores over time. The results showed a trend for alpidem to be more effective. Half of the alpidem group had a decrease of 50 percent or greater in their HAM-A scores with an almost equal effect on psychic and somatic symptoms. The most common side effects with alpidem and lorazepam were lightheadedness, drowsiness, and daytime tiredness. Moreover, treatment with alpidem did not manifest any withdrawal symptoms. Thus nonbenzodiazepine treatments are effective and safe for GAD.

Adult↗
PubMed1991

Dose response effects of zolpidem in normal geriatric subjects.

The dose-related hypnotic effects and effects on memory, performance, and daytime alertness of zolpidem 5, 10, 15, and 20 mg were compared with those of placebo in 30 elderly non-insomniac volunteers in a randomized, placebo-controlled, three-period crossover study. Subjects were randomized into two groups and received either placebo, zolpidem 5 mg, or zolpidem 15 mg or placebo, zolpidem 10 mg, or zolpidem 20 mg for 2 consecutive nights followed by 1 night of placebo during the same 3 nights of 3 consecutive weeks. Polysomnographic results showed statistically significant decreases in sleep latency and increases in sleep efficiency at all doses. Subjective reports also showed improved sleep latency, total sleep time, and sleep quality. REM percent was slightly decreased at doses of 10 and 20 mg. No consistent effects on memory or performance were observed, and the Multiple Sleep Latency Test showed no effects on daytime sleepines. There was no objective evidence of rebound insomnia upon drug discontinuation.

Aged↗
PubMed1989

Proliferation-related nucleolar antigens P145 and P120 associated with separate nucleolar elements and differences in tissue distribution.

Nucleolar antigens p145 and p120 are associated with proliferating cells (Freeman, J.W.; McRorie, D.K.; Busch, R.K.; Gyorkey, P.; Gyorkey, F.; Ross, B.E.; Spohn, W.H.; Busch, H. Cancer Res. 46:3593; 1986 and Freeman, J.W.; Busch, R.K.; Gyorkey, P.; Gyorkey, F.; Ross, B.E.; Busch, H. Cancer Res. 48:1244; 1988) and are not detectable in normal resting cells. Recent immunoelectron microscopic studies (Ochs, R.L.; Reilly, M.T.; Freeman, J.W.; Busch, H. Cancer Res. 48:6523; 1988) suggest that the two antigens have overlapping nucleolar localizations. In this study the nucleolus was physicochemically and biochemically studied to determine whether p145 and p120 were associated with a common nucleolar component. Antigen p145 was associated with 40-80 S ribonucleoprotein particles (RNPs), and the p145 antigen was not detected in HeLa cells following in situ RNAse digestion. P120 was found in a 40-80 S, RNAse resistant complex. Sequential extraction of HeLa nucleoli showed that most of antigen p145 was extractable in 10 mM Tris with 0.2% deoxycholate, whereas p120 was found in a nucleolar residue fraction requiring DNAse and high salt treatment for optimal extraction. Neither antigen p145 nor p120 was detectable in normal resting tissues. Antigen p145 was detected in all proliferating tissues examined, including a variety of malignant tumors (ten of ten), benign tissues including adenomas and hyperplasias (eight of eight), and in normal proliferating cells such as colonic epithelium and spermatogonia of the testes. Antigen p120 was not detected in all tumors, being absent in three of seven lymphomas and in one melanoma examined.(ABSTRACT TRUNCATED AT 250 WORDS)

Antigens, Nuclear↗
PubMed1987

Novel nucleolar antigens in autoimmune disease.

Antinucleolar antibodies are of interest in 2 important areas, namely, autoimmune diseases and specific products involved in the "mitogenic cascade." The former have delineated a series of novel nuclear and nucleolar elements including the recently described proliferating cell nuclear antigens (PCNA), some of which are present in the nucleolus only at specific times in the G1-S phase of the cell cycle. Important new proteins such as "fibrillarin" (34 kD/pI 8.5) and a 125 kD nucleotide containing protein have been identified with antinucleolar antibodies. Protein p145 is a nucleolar PCNA that is present in growing and dividing cells but not in normal resting tissues. Antinucleolar antibodies offer powerful tools, not only for identification of specific nucleolar proteins important in the cell cycle, but also for purification of their genes and analysis of mechanisms of gene control that operate the "time windows" of the cell cycle.

Amino Acid Sequence↗
PubMed1986

Studies on satellite nucleoli in human normal and leukemic lymphocytes.

Lymphocytes from normal and leukemic patients, and phytohemagglutinin-stimulated lymphocytes were investigated by means of immunofluorescence procedures and a silver reaction for the demonstration of proteins characteristic of nucleolus organizer regions in interphasic cells to provide basic information on the presence of satellite nucleoli in these cells. The results clearly indicated that satellite nucleoli are present in a limited but constant percentage of peripheral lymphocytes. An increased percentage of lymphocytes with satellite nucleoli was found only in leukemic patients and after silver staining. In contrast, a decreased percentage of satellite nucleoli was found 24 h after stimulation with phytohemagglutinin vitro. In leukemic patients, the discrepancy in the percentage of lymphocytes with satellite nucleoli between immunostained and silver-stained preparations may suggest that the silver reaction demonstrates the presence of an additional argyrophilic protein besides proteins B23 and C23, or altered forms of these proteins, which does not react with the specific antibodies.

Cell Nucleolus↗
PubMed1985

Purification of an 86-70 kDa nuclear DNA-associated protein complex.

In the course of studies on nucleolar antigens, monoclonal antibodies were developed, one of which recognized an 86 kDa antigen as shown by analysis of nuclear extracts from HeLa or Namalwa cells. Immunofluorescence studies on HeLa cells showed a nucleoplasmic and phase-dependent nucleolar localization of the monoclonal antibody was decreased after digestion with DNAase I but not with RNAase A. For purification, the antigen was released from nuclei by digestion with DNAase I and then purified by chromatography on DEAE cellulose, phosphocellulose and antibody-Sepharose affinity chromatography. Interestingly, the immunoaffinity purified product contained two polypeptide chains; the immunoreactive polypeptide had an Mr of 86 000 and a pI of 6.0. The complex also contained a 70 kDa, pI 6.5 nonantigenic polypeptide in a 1:1 ratio. The overall purification of the complex was 5700-fold. Both polypeptides contained approx. 15 mol% glutamic acid and the 70 kDa polypeptide contained approx. 15 mol% serine.

Amino Acids↗
PubMed1984

Immunofluorescence studies on proteins B23 and C23 in nucleoli of human lymphocytes.

Nucleoli of normal and leukemic lymphocytes were studied by cytochemical and immunofluorescence methods to provide more information on the nucleolar presence and distribution of proteins B23 and C23. Annular nucleoli of human lymphocytes represent a very convenient subject for such studies, since they consist of one centrally located large fibrillar center surrounded by RNP components. In such nucleoli, protein C23 was present mainly in the central nucleolar region and protein B23 was found mostly in the periphery. The nucleolar area immunostained for protein B23 was usually larger than that stained for protein C23. The distribution of protein C23 appeared to be similar to that of intensely stained nucleolar argyrophilic components. No substantial differences were found between the distribution of proteins B23 and C23 in nucleoli of normal and leukemic lymphocytes. In lymphocytes of patients treated with chemotherapy, the immunofluorescence was diminished for protein B23 and particularly so for protein C23.

Cell Nucleolus↗
PubMed1984

Does head-turning during a seizure have lateralizing or localizing significance?

Forced lateralized head-turning, occurring as the first clinical sign in 106 epileptic seizures in 43 patients, was recorded on videotape simultaneously with the EEG. Forty-five ictal EEGs were obtained with stereotaxically implanted intracerebral electrodes. Forced head-turning was seen with seizures that had a frontal, temporal, unilateral diffuse, or a generalized onset in the EEG. Ipsilateral was as common as contralateral head-turning in all groups, including the seizures with frontal lobe onset. Initial head-turning in a seizure has no localizing or lateralizing significance.

Adolescent↗
PubMed1983

Localization of nucleolar phosphoproteins B23 and C23 during mitosis.

Nucleolar phosphoproteins B23 and C23 were simultaneously localized in unsynchronized male rat-kangaroo PtK2 cells during mitosis using a mouse monoclonal antibody against protein B23 and a rabbit antibody against protein C23. The distribution of proteins B23 and C23 during mitosis was compared with the distribution of the silver staining protein. During interphase, proteins B23 and C23 were both localized to the nucleolus. As the nucleolus disappeared in prophase, the distribution of protein B23 became nucleoplasmic, whereas most of protein C23 remained associated with the disappearing nucleolus. Throughout metaphase and anaphase protein B23 was found associated with the chromosomes, whereas protein C23 seemed to disappear. When the nucleolus reformed during telophase, protein C23 appeared first in 'prenucleolar bodies' and then in the nucleolus, whereas protein B23 did not appear in the nucleolus until late telophase or early G1 phase. Silver staining during mitosis closely paralleled the distribution of protein C23, supporting previous conclusions that protein C23 is a silver staining nucleolus organizer region (NOR) protein [19, 20].

Animals↗
PubMed1982

A pathologic basis for Kleine-Levin syndrome.

A patient with Kleine-Levin syndrome, typical except that onset was at 39 years of age, died during a symptomatic period. Autopsy disclosed recent and old lesions in the medial thalamus involving intralaminar, medial, and some dorsal nuclei as well as the pulvinar. Despite massive microglial infiltration, there was minimal neuronal loss. The hypothalamus was not involved. The findings suggest a viral cause for Kleine-Levin syndrome.

Feeding and Eating Disorders↗
PubMed1982

Renal lesions in ischaemic kidneys infused with haemoglobin: an electron microscopic study.

Male Wistar rats were used to study changes in ultrastructure of proximal renal tubular cells after an haemoglobin (Hb) load with or without temporary renal ischaemia. An i.v. injection of stroma-free Hb was given either 30 min before, immediately after, or 2 h after ischaemia. Appropriate control groups were used for comparison. Electron microscopic examination was performed on kidneys removed 48 h after treatment. Hb transport and degradation was markedly delayed by renal ischaemia. Hetero-ambi- and autolysosomes were found after Hb load, and the number of lysosomes was higher in animals with ischaemia than in sham-operated controls given Hb. Renal cellular damage was more pronounced in rats given Hb either 30 min before or 2 h after ischaemia than in those subjected to either Hb load or ischaemia alone. The findings show deleterious effects of haemoglobinuria in conjunction with renal ischaemia.

Animals↗