Biomedical subjects
Publications and source records attributed to A Shahar.
Ciprofloxacin activity against Leptospira interrogans serogroup icterohaemorrhagiae was studied in vitro and in an animal model. The MBC of ciprofloxacin was 0.6 microgram/ml. Three of three Syrian hamsters died 8 to 9 days after intraperitoneal challenge with 10(6) leptospires. In contrast, five of six animals given ciprofloxacin 3 or 5 days after challenge survived.
The cytotoxic effects of ethylcholine aziridinium ion (AF64A) were studied in primary cultures prepared from either whole brain, septum, or midbrain of fetal rats. AF64A, at concentrations up to 22.5 microM, significantly reduced the number of acetylcholinesterase-stained cells without affecting the number of dopaminergic neurons or their ability to take up and release [3H]dopamine. Many of the survived acetylcholinesterase-stained cells appeared with intact somata but damaged processes, indicating a retrograde degeneration starting at the nerve terminal. Higher concentrations of AF64A (greater than 22.5 microM), caused general toxicity which was expressed by degeneration of various neuronal and glial cells. Choline (500 microM), significantly protected the cells from AF64A induced cytotoxicity. The results are consistent with a previously described kinetic model, that predicted a dual action of AF64A: selective cholinotoxicity at low concentrations and non-selective cytotoxicity at higher concentrations.
Auditory functions of 32 Israeli soldiers with posttraumatic stress disorder (PTSD) were evaluated and compared with those of 32 matched controls without PTSD. The evaluation included peripheral auditory functions, tolerance to noise, and central auditory informational functions. Tolerance of intense auditory stimuli by PTSD patients was similar to that of controls. Significant differences were found between left and right ear central auditory functions in a subgroup of 13 PTSD subjects, but neither in other PTSD patients nor in controls. These findings are discussed in the light of previous research concerning abnormal responses to auditory stimulus in PTSD, hemispheric disconnection, alexithymia, and psychosomatic disorders.
Vitamin B12 and folate serum levels were studied in 30 patients with obsessive compulsive disorder (OCD), and in two control groups comprised of 30 chronic schizophrenics and 30 normal healthy subjects. Six patients (20%) of the OCD group had abnormal low levels of vitamin B12. This prevalence was significantly higher than that of the control groups. No clinical neurological or haematological abnormalities accompanied the reduced vitamin B12 levels. Possible implication of this finding for the pathophysiology of OCD in a subgroup of patients and the possibility that the B12 deficiency could be the consequence rather than the cause of OCD are suggested.
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The natural history of individuals with acute acoustic trauma who ceased to be exposed to impact noise was examined. Retrospective follow-up was carried out for 4 years on patients who were qualified as disabled following acoustic trauma with permanent threshold shift. Eight hundred forty-one individuals (1682 ears) were examined, of which 1514 ears with acoustic trauma were included in the study group; 150 individuals (300 ears) who continued to be exposed to impact noise even after discovery of acoustic trauma comprised the control group. In the latter, as long as exposure to gunfire continued, the severity of acoustic trauma increased. In the study group, during the first year after injury, changes were observed in hearing, whether improvement or deterioration; after this period, hearing loss appeared to be final. We suggest that, after 1 year following acute acoustic trauma, the associated hearing loss be considered as final, provided there is no further exposure to noise. This finding holds great importance from the medicolegal standpoint, an aspect that is unclear in the literature. It clarifies that beyond the period of 1 year after initial exposure, the pathologic process ceases (as long as there is no additional exposure to noise or gunfire). Further hearing deterioration beyond this period is not related to the initial acoustic trauma but rather to other factors.
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A combination of techniques, based mainly on the stress inoculation training approach, was used to treat severe self-mutilating behavior in a 32-year-old woman who for 15 years had manifested different kinds of this type of behavior. In 18 therapy sessions over 6 weeks in a psychiatric inpatient setting she achieved complete control of the self-mutilating behavior. After a year of follow-up she was completely symptom free and had made additional social and personal gains.
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Theiler's murine encephalomyelitis viruses causing both fatal encephalitis (GDVII virus) and chronic demyelinating disease (WW virus) are capable of replicating in isolated Schwann cell cultures. Light microscopy combined with immunohistochemical staining of viral antigens revealed that large numbers of Schwann cells infected with the two viruses show cytopathic effect (rounding) and contain viral antigens. Electron microscopy of virus-infected Schwann cells shows that the morphological alterations that the cells undergo following infection by the two virus isolates are different. In the early stages of GDVII and WW virus infection, different inclusion bodies are formed in the cells cytoplasm. At late stages of the infection GDVII virions are found in all infected cells and are arranged in crystalline arrays around inclusion bodies. In contrast, in WW virus-infected Schwann cells only in few cells virions were observed and they appeared aligned between two membrane units.
The cytopathic effects caused by Theiler viruses to myelinated organotypic spinal cord cultures was studied by light and electron microscopy. Heavily myelinated cultures, 2-3 weeks in vitro were infected with WW and GD VII viruses. Mock infection served as control. On light microscopy cytopathic effects and demyelination became evident about 16-17 hr after infection. Demyelination observed in WW virus-infected cultures was much more pronounced than in cultures infected with GD VII viruses. The myelin in mock-infected cultures remained undamaged. Electron microscopy revealed that in control cultures cells were intact, exhibiting numerous synapses and a network of axons enwrapped by multilayered myelin sheaths. Virus-infected spinal cord slices showed that a more severe cytotoxicity was caused by GD VII virus than by WW virus. The cytopathology included accumulation of cytoplasmatic vacuoles, margination of chromatin, synapse and cell disintegration, and various degrees of demyelination. Several GD VII virions were observed, arranged in crystalline arrays, mainly in electron-opaque cells, but not within axons. WW virions on the other hand were only occasionally encountered.
The authors evaluated high-affinity [3H]imipramine binding and [3H]serotonin uptake to platelets in eight adolescent and 10 adult patients who met DSM-III criteria for obsessive-compulsive disorder in comparison with those of normal control subjects of similar ages. The maximal binding of [3H]imipramine was significantly lower in adults and adolescents with obsessive-compulsive disorder than in the control subjects. No differences between groups in the affinity of [3H]imipramine to its binding sites or in serotonin uptake kinetic measures were detected. The lower density of [3H]imipramine binding sites in platelet membrane in patients with obsessive-compulsive disorder might implicate involvement of the serotonergic system or might represent an adaptive response to a chronic disease.
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ABRs and EEGs were recorded in anaesthetized rats during whole body hyperthermia. ABR amplitudes were decreased during warming, with little recovery as body temperature was lowered. The latencies of the ABR waves decreased with warming and increased with subsequent cooling. The major latency changes were in the later ABR waves. Warming was accompanied by suppression of the EEG. These results point out that ABR evaluation of patients must take into account elevated body temperatures. Since it has been shown that the rat can serve as a model of the effects of heat on man, an attempt is made to relate these ABR and EEG findings in rats to studies of human psychomotor performance during heat exposure.