Evaluation of the behaviour of a thermal diffusion sensor in a high field strength magnetic resonance system: an experimental study.

Patients with acute brain pathology requiring ferromagnetic bio-medical implants for on-going invasive monitoring are largely excluded from the benefits of MRI scanning. We evaluated the behaviour of a thermal diffusion cortical blood flow (TD-CBF) sensor both in vitro (phantom gelatin model) and in vivo environments in a high field strength MRI system.Two baboons underwent cranial subdural implantation of 2 TD-CBF sensors/hemisphere and a single left parietal sensor was implanted subcortically to determine any deleterious effects. Using standard MRI sequences, artefact size, thermal effects, current generation, movement and reliability of recordings were assessed during scanning.The deflection forces were negligible, no observable thermal effects were demonstrated, while wide fluctuations in cerebral blood flow recordings were recorded. Mean image artefact size for implanted sensors was 6 times larger than in vitro. Patients with an implanted TD-CBF sensor may be safely imaged provided the device is disconnected. The MRI images obtained are of an acceptable quality.     

Cytoplasmic architecture of the axon terminal: filamentous strands specifically associated with synaptic vesicles

Cytoplasmic architecture of axon terminals in rat central nervous tissue was examined by quick-freeze deep-etch method to determine how synaptic vesicles and their associated cytoplasmic environment are organized in the terminal and to know how these structures participate in the mechanism for neurotransmitter release. The axoplasm is divisible into two domains: one occupied by mitochondria in the middle of the terminal, called the mitochondrial domain, the other situated in the periphery and exclusively filled with spherical synaptic vesicles, 50-60 nm in diameter, the synaptic vesicle domain. The most characteristic feature of the mitochondrial domain was the appearance of many microtubules connected with mitochondria by filamentous strands. Large vesicles, 80-100 nm in diameter, were preferentially associated with the mitochondrial domain, and linked with microtubules wherever they appeared. The cytoplasmic matrix of the synaptic vesicle domain showed a more fibrillar texture than that of the mitochondrial domain because of the distribution of filamentous strands associated with synaptic vesicles. These strands were significantly thicker and longer (mean 11.7 nm thick and 42.7 nm long) than those linking membrane-bound organelles to microtubules (mean 8.3 nm thick and 23.0 nm long), and connected vesicles to one another or to the plasma membrane, making a complicated network around the vesicles. Further, both strands were significantly different in dimension from actin filaments (mean 9.9 nm thick and 73.5 nm long) showing 5-nm axial periodicity. These strands, especially synaptic vesicle-associated ones including their network, were readily broken down in the most part by detergent treatment or chemical fixation, indicating that they are very delicate in nature. Granular materials, which are spherical and vary in size (6-20 nm in diameter), are also more conspicuous in the synaptic vesicle domain than in the mitochondrial domain. More fibrillar and granular cytoplasmic structure of the synaptic vesicle domain may be crucial for synaptic vesicles to perform an essential role in releasing the transmitter.     

Acute gluteal abscess following intramuscular chloroquine injection: a clinical and experimental study

This prospective study contains clinical and experimental parts. In the clinical study, 125 patients given intramuscular chloroquine for malaria were followed for 2 months in order to detect local injection site complications. Adequate local antiseptic conditions were ensured before giving the injection. Twenty-three patients (18.4%) had minimal local reaction in the form of redness, induration and/or a lump. No pyogenic abscess was noted in contrast to a previous report. In the second part of the study, an experimental animal (Green monkey) was given either chloroquine phosphate, Ampiclox or normal saline intramuscularly. The injection site was later biopsied and histologically examined. Intramuscular chloroquine was found to cause severe inflammatory reactions and muscle necrosis, whereas other injections had very minimal local effects. It is concluded that intramuscular chloroquine causes muscle necrosis which may lead to acute pyogenic abscess if minimal contamination takes place.     

Present phage types and antibiotic susceptibility of salmonellae.

A total of 168 strains of Salmonella were isolated in the Command Pathology Laboratory (WC) Delhi Cantt during the year 1990. Out of this, 143 were Salmonella typhi, 17 Salmonella paratyphi A, 7 Salmonella typhimurium and 1 Salmonella manhattan. The commonest phage type and biotype of Salmonella typhi was type E1 and type 1 respectively. The dominant biotype of Salmonella paratyphi A was type I. There was a very high degree of multidrug resistance of most of the strains. But all the strains were sensitive to ciprofloxacin and norfloxacin.     

Leflunomide-induced peripheral neuropathy.

Two cases of leflunomide-induced peripheral neuropathy are described; in a 60-year-old woman with sero-negative polyarthralgia-myalgia syndrome and a 65-year-old man with sero-negative rheumatoid arthritis, both treated with leflunomide at 20mg/day. Nerve conduction studies and electromyogram showed sensorimotor axonal neuropathy in both cases. An alternative cause for the axonal neuropathy was excluded by extensive investigations, including cerebrospinal fluid examination and nerve biopsy in the second patient. Both patients stabilized symptomatically and electrophysiologically upon cessation of leflunomide. It is possible that leflunomide-induced peripheral neuropathy has been under-reported and under-recognized.     

Psychiatrische Notfälle

Pre-clinical psychiatric emergency situations (PES) have been identified to be the third major reason for emergency physician (EP) calls with a frequency of approximately 10%. Until now, there are no investigations about regional differences between urban and rural regions in frequencies, diagnoses, or treatment necessities of PES. A retrospective analysis of all anonymised EP protocols of one year in a metropolitan (Hamburg) and a rural region (Schaumburg County) was performed with the same methodological approach. In both regions, the frequency of PES was revealed to be near 10%. Gender and age of psychiatric patients as well as reasons for calls were comparable. In Schaumburg County, much less disturbances due to illegal drugs were observed. However, more patients had to be treated because of suicide attempts and alcoholism. All in all, disturbances seemed less life-threatening than in the metropolitan region. In conclusion, frequency and kind of PES do not differ substantially between rural and urban regions. Considering the prevalence of PES, the particularities in diagnosis and treatment and the dissipation of institutionalised psychiatric care mainly in rural regions, more training in psychiatric subjects is needed.     

Immunologic aspects of pneumoconiosis.

This review summarizes recent research bearing on the role played by cells of the immune system in the development of pneumoconiosis. Findings related to the cellular and humoral immune responses to silica and asbestos are highlighted. Experimental results from humans and animal models are integrated into our current understandings of cellular and cytokine-mediated pathways leading to the generation of immune responses that may contribute to fibrogenesis and fibrosis. Potential mechanisms leading to the generation of an immune response by particulates are discussed, together with the indirect effects of particulates on fibroblasts by way of the cytokine network in the lung. Finally, suggestions are given for future research to help further elucidate the relationships between the cellular components of the immune system of the lung and the fibroblast that lead to fibrosis.     

Collateral sensitivity to nitrosoureas in multidrug-resistant cells selected with verapamil.

We have examined the effects of the nitrosoureas, streptozotocin (STZ) and 1,3-bis(chloroethyl)-1-nitrosourea (BCNU), on a human multiple myeloma cell line, RPMI 8226, and its drug-resistant variants. Cell lines selected for doxorubicin (DOX) resistance alone displayed a STZ and BCNU cytotoxicity profile similar to that of the parent cell line. In contrast, two of the drug-resistant variants selected with DOX plus verapamil, an agent which inhibits P-glycoprotein-mediated multidrug resistance, displayed a collateral sensitivity to STZ and BCNU. Verapamil was included in the selection protocol because it has been shown to inhibit the P-glycoprotein-mediated multidrug resistance phenotype and is now in clinical trials as a chemosensitizing agent. The collateral sensitivity to these nitrosoureas seen in the DOX plus verapamil-selected cell lines is due to the functional loss of a DNA repair molecule, O6-Methylguanine DNA methyltransferase (MGMT). The functional loss of MGMT is secondary to the loss of MGMT gene expression. The loss of MGMT gene expression is not due to loss or gross rearrangement of the MGMT-coding region. If this selection pressure applied in vitro reflects the in vivo situation, then new chemotherapeutic strategies may be devised to exploit this phenomenon. These cell lines will serve as useful models for delineating mechanisms which govern MGMT expression.