Pleiotropic effect of sodium arsenite on Escherichia coli

The effects of sodium arsenite at a sub-MIC concentration (25 mg/l) upon different bacterial functions were studied. This compound reduced the killing activity of nalidixic acid, amikacin, and meropenem. It also promoted the loss of F'lac from bacterial hosts and increased the number of recombinants in conjugation and transduction experiments. Transposition of Tn9 was also enhanced by the salt. In addition, sodium arsenite abolished the lethal effect of temperature on thermosusceptible DNA synthesis mutants in a similar manner to that seen in an anaerobic environment. Finally at a low dose, it induced the SOS response, and the related production of recA-dependent enzymes was reduced as the sodium arsenite concentration increased. It has been suggested that arsenite primarily affects the uvrA gene product, influencing the other bacterial functions studied. The energetic depletion caused by this compound appears to play a role in the activity of autolytic enzymes.     

K-ras gene mutational analysis supports a monoclonal origin of biphasic pleomorphic carcinoma of the lung.

We investigated 27 pleomorphic carcinomas of the lung for exon 1 K-ras gene mutations using polymerase chain reaction-single-strand conformation polymophism analysis and direct sequencing. All pleomorphic carcinomas were biphasic, that is, composed of an adeno-, squamous- or large-cell-carcinomatous component associated with a spindle- and/or giant-cell component. Of 27 cases, six (22%) showed K-ras codon 12 mutations, which is a figure higher than that previously reported on in pure sarcoma-like pleomorphic carcinomas. Five tumors displayed the same mutation in both the epithelial and the sarcomatoid components, whereas in one tumor the mutation was restricted to the epithelial component. All mutations occurred in smokers, and were transversions, including GGT (glycine) to TGT (cysteine) change in two cases, to GCT (alanine) in two and to GTT (valine) in two. No significant relationships were found between the occurrence and type of mutations and patients' survival or any other clinicopathological variable, suggesting that K-ras mutations are early events in the development of these tumors. Our results indicate that most, though not all, biphasic pleomorphic carcinomas of the lung are monoclonal in origin, and that cigarette smoking may have a causative role in the development of K-ras alterations in these tumors, as all mutations are transversions.     

Prevalence rates and psychosocial characteristics associated with depression in pregnancy and postpartum in Maltese women

BACKGROUND: Investigators have commented on the apparent high prevalence of psychiatric symptoms in pregnancy. In Malta there is lack of epidemiological data and therefore, the prevalence of depression during pregnancy and at 8 weeks postpartum among a community sample of Maltese women was carried out. METHOD: A random sample of 239 pregnant women were interviewed at booking using a detailed sociodemographic history, the revised version of the clinical interview schedule (CIS-R) and Maltese translation of the Edinburgh postnatal depression scale (EPDS). The CIS-R was again administered over the phone at 36 weeks and the EPDS sent by post. At 8 weeks postpartum, the CIS-R, modified version of the social maladjustment schedule and the EPDS were again administered to 95.8% of women. RESULTS: The point prevalence of depression meeting ICD-10 research criteria was 15.5% at booking, 11.1% in the third trimester and 8.7% postpartum of which only 3.9% had an onset since delivery. CONCLUSIONS: The low rate of new onset postpartum depression compared with other studies in our sample may be attributable to the social support available to women living in a cohesive Catholic island community. LIMITATION: The follow-up was limited to 8 weeks postpartum. No control group was used to compare the prevalence of depression in women who did not recently have a baby.     

The theoretical small signal impedance of the frog node,Rana pipiens

Summary The small signal impedance of the frog node is calculated for frequencies from 1 Hz to 10,000 Hz and transmembrane potentials from –80 mV to –30 mV by linearizing the voltage clamp equations of Dodge [7] and Hille [8]. The modulus of the impedance is presented for the total system, and separately for the potassium and sodium systems as a function of frequency and voltage. There is a broad resonance in the total impedance with a voltage-dependent peak frequency. At 22°C, in the range –75 mV to –45 mV, the peak frequencies occur between 50 and 500 Hz. Removing the potassium system leaves a relatively shapr resonance centered around 200 Hz at –45 mV.     

Erratum: Neurofibromatosis type 1 (NF1): Identification of eight unreported mutations in NF1 gene in Italian patients

In the original version of this article, the title was incorrect. Please find the correct title given here. The publisher deeply regrets this error. The original article to which this Erratum refers was published in Human Mutation 22:179–180 Human Mutation(2003) 22(2) 179–180     

Epidemiological and Environmental Investigations of Legionella pneumophila Infection in Cattle and Case Report of Fatal Pneumonia in a Calf

A fatal pneumonia due to Legionella pneumophila was diagnosed in a young calf reared in a dairy herd located in northern Italy. Clinical symptoms consisted of watery diarrhea, hyperthermia, anorexia, and severe dyspnea. The pathological and histological findings were very similar to those observed in human legionellosis. Legionella pneumophila serogroup 1 (SG1) and SG10 were isolated from the calf’s lung, and L. pneumophila SG1 was isolated from the calf’s liver. L. pneumophila SG1 was also demonstrated in the lung tissue by immunofluorescence and immunohistochemical examinations. Nine of 10 L. pneumophila SG1 isolates belonged to the Olda subtype, and 1 belonged to the Camperdown subtype. A very low prevalence of antibodies to Legionella was detected in cows and calves reared in the same herd. Cultures of aqueous sediment of an old electric water heater which supplied hot water for the feeding of the calves yielded L. pneumophila SG1. Four of the colonies tested belonged to the Olda subtype. Ten clinical and four environmental isolates were examined for the presence of plasmids. Nine of them were also examined by pulsed-field gel electrophoresis assay, and the same patterns were found for L. pneumophila SG1 Olda strains isolated from the calf and from the electric heater. This is the first report of a documented case of a naturally occurring Legionella pneumonia in an animal. Cattle probably act as accidental hosts for legionellae, much the same as humans.     

Role of primate basal ganglia and frontal cortex in the internal generation of movements

In order to more comprehensively assess the role of the basal ganglia in the internal generation of movements, we studied the activity of neurons in the head of the caudate and in the rostral putamen in relation to the execution of movements. Monkeys performed self-initiated and stimulus-triggered arm reaching movements in separate blocks of trials. With stimulus-triggered movements, 217 striatal neurons increased their activity after the trigger stimulus (127 in caudate, 90 in putamen). Of these, 68 neurons showed time-locked responses to the trigger stimulus, with a median latency of 60 ms, that were independent of visual or auditory stimulus modalities. Three quarters of responses were conditional on a movement being performed. These responses may participate in neuronal processes through which the reception of a stimulus is translated into the execution of a behavioral reaction. Further, 44 neurons increased their activity before the earliest muscle activity without being clearly time-locked to the stimulus (148-324 ms before movement onset), 55 neurons were activated later before the movement, and 50 neurons were activated after movement onset. With self-initiated movements, 106 striatal neurons showed movement-related activity beginning up to 460 ms before movement onset (52 in caudate, 54 in putamen). Comparisons between the two types of movement were made on 53 neurons with premovement activity beginning more than 500 ms before self-initiated movements. Only one fifth of them also showed movement-related activity with stimulus-triggered movements, including trigger responses. Comparisons among 39 neurons with movement-related activity during self-initiated arm movements showed that about half of them also showed movement-related activity with stimulus-triggered movements. These data demonstrate a considerably segregated population of striatal neurons engaged in the internal generation of movements, whereas processes underlying the execution of movements appear to involve overlapping neuronal populations.     

Lightly crosslinked liquid crystalline epoxy resins: The effect of rigid-rod length and applied stress on the state of order of the cured thermoset

Lightly crosslinked liquid crystalline epoxy resins were synthesized by reacting rigid rod epoxy-terminated molecules with decanedioic acid (SA). The obtained networks exhibited a smectic phase even in the case of 2,6-bis(2,3-epoxypropoxy)naphthalene, whose aspect ratio is very low. Upon application of uniaxial stress, a smectic phase was surprisingly obtained also for the system obtained by reacting p-bis(2,3-epoxypropoxy)-benzene (QH), whose aspect ratio is practically equal to one, and SA. Stretching of the smectic samples above the glass transition temperature determines orientation of polymer chains, yielding considerably high values of the order parameter S. Thermomechanical analysis showed, for one of these systems, that stretching induces a shift of the isotropization temperature to higher values.