Clustering of Serratia marcescens infections in a neonatal intensive care unit.

OBJECTIVES: To study clusters of infections caused by Serratia marcescens in a neonatal intensive care unit (NICU) and to determine risk factors for S. marcescens infection or colonization. DESIGN: Genotyping of S. marcescens isolates was performed by pulsed-field gel electrophoresis (PFGE). A retrospective case-control study was conducted. SETTING: A tertiary-care pediatric hospital with a 16-bed NICU. PATIENTS: All neonates with at least one culture positive for S. marcescens in the NICU during December 1999 to July 2002. Case-patients (n = 11) treated in the NICU during December 1999 to February 2000 were included in the case-control study. Neonates treated in the NICU for at least 72 hours during the same period with cultures negative for S. marcescens were used as control-patients (n = 27). RESULTS: S. marcescens was cultured from 19 neonates; 9 were infected and 10 were colonized. PFGE analysis identified three epidemic strains; each cluster consisted of identical isolates, except one isolate in the first cluster that was different. The risk factors identified were low birth weight, prematurity, prolonged respiratory therapy, prolonged use of antibiotics, and maternal infection prior to delivery. Overcrowding and understaffing were recorded simultaneously with the clusters. CONCLUSIONS: PFGE analysis showed three independent clusters. Several factors contributed to spread of the epidemic strains: (1) there were many severely premature and susceptible neonates, (2) the NICU was overcrowded during the clusters, and (3) transmission was likely to occur via the hands of staff. Cohorting and improvement of routine infection control measures led to the cessation of each cluster.     

Four‐color CGH: A new method for quality control of comparative genomic hybridization

Comparative genomic hybridization (CGH) has become a widely used method in molecular cytogenetics to screen for copy number aberrations in human malignancies. Although the hybridization protocol is relatively simple, the validation and quality control of CGH have remained difficult. We describe here a new modification of CGH, four‐color CGH, which is based on conventional CGH with an added Cy5‐labeled second reference DNA, that serves as an internal standard in every hybridization. The internal standard aids in identifying inconsistently hybridized chromosomal regions (such as 1pter, 19, 22). When using a special second reference DNA (from a sex‐mismatched trisomy 13 cell line) for four‐color CGH, it is possible to standardize the dynamic range of hybridization. The four‐color CGH modification is simple to adopt, requiring only the addition of Cy5‐labeled reference DNA to the existing hybridization protocol. The principles and the modifications of the CGH image analysis software are described in detail. Genes Chromosomes Cancer 24:112–118, 1999. © 1999 Wiley‐Liss, Inc.     

Germ cell mutagenicity of three metabolites of 1,3-butadiene in the rat: Induction of spermatid micronuclei by butadiene mono-, di-, and diolepoxides in vivo

Three metabolites of the industrial chemical 1,3-butadiene (BD), namely butadiene monoepoxide (BMO, 3,4-epoxy-1-butene), diepoxide (DEB, 1,2;3,4-diepoxybutane), and diolepoxide (DE, 3,4-epoxybutane-1,2-diol) were studied for germ cell mutagenicity using the rat spermatid micronucleus (MN) test. All three epoxides increased slightly, but significantly, the frequency of spermatid MN. The most sensitive stage to the action of BMO and DEB was preleptotene (meiotic S phase) harvested at 18-day time intervals after treatment. The dose-response for BMO followed a second order curve at this time interval, with maximum MN induction at the dose of 186 μmol/kg and lower induction at higher doses. Late stages of the meiotic prophase (late pachytene-diplotene-diakinesis) also showed some sensitivity to the three epoxides. Stem cell spermatogonia were affected by DEB as observed by a slight induction of spermatid micronuclei 50 days aftertreatment. No clear cytotoxic effects were observed by measuring testicular weight or cell numbers of seminiferous epithelial stage I 18 days after the treatments. DEB at the dose 387 μmol/kg caused a slight inhibition of spermatogonial DNA synthesis in stage I and a delay of meiotic DNA replication observed in stage XII 72 hr after treatment. Since BMO is able to induce spermatid MN in the rat, the present results, together with previous data, indicate that rat bone marrow MN results that are negative for both BD and BMO cannot directly predict mutagenicity in male germ cells. The results also emphasize that tissue-, species-, and strain-specific differences in metabolism have to be taken into account when the genetic risks of human butadiene exposure are evaluated. The results support the conclusion that 1,3-butadiene is a germ cell mutagen--possibly also in humans. Environ. Mol. Mutagen. 29:230–239, 1997. © 1997 Wiley-Liss, Inc.     

Deep brain stimulation for monogenic Parkinson’s disease: a systematic review

Journal of Neurology - Deep brain stimulation (DBS) is an effective treatment for Parkinson’s disease (PD) patients with motor fluctuations and dyskinesias. The key DBS efficacy studies were...     

Effects of repeated noxious thermal stimuli on the responses of neurons in the lateral cervical nucleus of cats: evidence for an input from A-nociceptors to the spinocervicothalamic pathway

Recent findings indicate that the lateral cervical nucleus (LCN) in cats is capable of transmitting to the ventrobasal thalamus information that may contribute to nociception. In the present study, we examined the effects of repeated noxious thermal stimulation on the responses of LCN neurons in unanesthetized cats that were decerebrated and partially spinalized. Seventeen LCN neurons were recorded that responded to noxious mechanical stimuli. The most responsive area of the receptive field of each neuron was exposed to repeated and sustained thermal stimuli of up to 55 degrees C. Such stimulation decreased the thermal thresholds of all 17 LCN neurons and increased the frequencies of their responses to identical thermal stimuli. The characteristics of this sensitization suggest that the spinocervicothalamic pathway receives a prominent input from A-nociceptors.     

Eliminating carcinogenic acetaldehyde by cysteine from saliva during smoking.

Tobacco smoking is one of the strongest risk factors not only for lung cancer but also for cancers of the upper gastrointestinal tract. Acetaldehyde has been shown to dissolve into the saliva during smoking and to be a local carcinogen in the human upper digestive tract. Cysteine can bind to acetaldehyde and eliminate its toxicity. We developed a tablet that releases cysteine into the oral cavity during smoking and could therefore be a potential chemopreventive agent against toxicity of tobacco smoke. In this study, the efficacy of l-cysteine-containing tablets to reduce the carcinogenic acetaldehyde in the saliva during tobacco smoking was examined. Seven volunteers smoked five cigarettes. During every smoking period, each volunteer sucked a blinded tablet containing 0, 1.25, 2.5, 5, or 10 mg of l-cysteine. Acetaldehyde was analyzed from salivary samples gas chromatographically at 0, 5, and 10 minutes from the beginning of the smoking. All tablets containing l-cysteine reduced highly significantly the salivary acetaldehyde; 5 mg of l-cysteine was the minimum concentration to totally eliminate the acetaldehyde from saliva. The mean salivary acetaldehyde concentrations in samples collected immediately after smoking with 0, 1.25, 2.5, 5, or 10 mg of l-cysteine were 228+/-115 micromol/L, 85+/-42 micromol/L (P=0.007), 9+/-7 micromol/L, 0.09+/- 0.2 micromol/L, 0+/- 0 micromol/L (P<0.001), respectively. In conclusion, carcinogenic acetaldehyde could be totally inactivated in the saliva during smoking by sucking tablet containing 5 mg of l-cysteine. Even a small reduction of the carcinogenicity of cigarette smoke could gain benefit at the population level. Hence, this finding warrants for further clinical trials for l-cysteine tablet in the prevention of upper digestive tract cancers in smokers.     

Brain serotonin 1A receptor binding in bulimia nervosa.

BACKGROUND: Selective serotonin reuptake inhibitors (SSRIs) are the first choice for the pharmacologic treatment of bulimia nervosa, but there are no published data on the putative altered serotonin (5-HT) receptor characteristics in patients with bulimia. Experimental studies suggest that the therapeutic antidepressant effect of SSRIs is mediated via 5-HT(1A) receptors. The aim of this study was to measure brain 5-HT(1A) receptor binding among nonmedicated patients with bulimia nervosa. METHODS: Positron emission tomography (PET) with a selective 5-HT(1A) ligand, [11C]WAY-100635, was performed on eight unmedicated patients with bulimia and 10 healthy comparison subjects. RESULTS: The binding potential values were greater in patients than in control subjects in all brain regions studied. The most robust differences were observed in the angular gyrus, the medial prefrontal cortex, and the posterior cingulate cortex. CONCLUSIONS: These results suggest that brain 5-HT(1A) receptor binding is increased in several cortical areas in patients with bulimia nervosa during their state of impulsive binge eating.     

Songs produced by the females of theDrosophila virilis group of species

Females of theDrosophila virilis group of species may vibrate their wings during courtship producing songs consisting of trains of successive sound pulses (pulse song) or sinusoidal hums (sine song). In the present study we describe these songs and study their role in courtship using a transition analysis. To find out which songs should be classified as pulse songs and which ones as sine songs, we studied the inheritance of different song types in interspecific F₁ hybrids. In only a few species did the females produce large quantities of song in successful courtships. The males' reactions to female songs varied from licking and singing to stopping the courtship. Pulse trains with short and long intervals between successive pulses appeared to be different forms of the pulse song, while sine song (sinusoidal hums) was inherited independently of the pulse song.