Does stratifying surgical site infection rates by the National Nosocomial Infection Surveillance risk index influence the rank order of the hospitals in a surveillance system?

We performed a study to investigate whether stratification of surgical site infection (SSI) rates according to the National Nosocomial Infection Surveillance (NNIS) risk index could lead to a better basis for comparison of surgical units compared with simpler methods. A retrospective analysis of surveillance data of the German national nosocomial infection surveillance system (KISS, Krankenhaus Infektions Surveillance System) was completed with data from 234 volunteer surgical departments. In all, 4275 SSIs of 223 367 operations from 12 surgical procedure categories were surveyed over a 66 month period from January 2001 to June 2006. Active SSI surveillance was performed according to the NNIS method and Centers for Disease Control and Prevention definitions. For each department, two SSI rates were calculated per procedure: the crude infection rate (CIR) and the risk-adjusted standardised infection ratio (SIR) based on the NNIS risk index. Ranking was performed for the departments using both rates. The correlation between the two ranking positions was investigated by Spearman's correlation coefficient (P). For all 12 operative procedure categories, there was a strong correlation between the CIR and the SIR (P > 0.95). A department's rank position does not change remarkably when the CIR, which is easier to understand and simpler to record, is taken into account for comparison instead of the SIR.

[Surgical site infection rates using a laparoscopic approach: results of the German national nosocomial infections surveillance system]. / Wundinfektionen nach laparoskopischen Operationen: Ergebnisse des Krankenhaus-Infektions-Surveillance-Systems.

BACKGROUND: Our aim was to assess the impact of laparoscopy on surgical site infections. METHODS: An analysis was performed using the data of the German national nosocomial infections surveillance system (Krankenhaus-Infektions-Surveillance-Systems, KISS) collected during the period from January 2001 to June 2006. Univariate and multivariate analyses were used to investigate the influence of age, gender, ASA score, duration of surgery, wound contamination class and surgical technique. RESULTS AND CONCLUSIONS: A total of 18,249 appendectomies, 32,912 herniorrhaphies, 42,949 cholecystectomies and 19,523 colon operations were analysed. The overall surgical site infection rate was significantly higher (2.6-fold) for the open approach compared to laparoscopically performed appendectomies. For herniorrhaphies, cholecystectomies and colon operations the corresponding odds ratios were 3.40, 3.22 and 1.20 respectively. Whenever possible a laparoscopic approach should be used.

Distribution of cGMP-dependent protein kinase type I and its isoforms in the mouse brain and retina.

Nitric oxide (NO) modulates a variety of processes in the mammalian brain, but the mechanisms of neuronal NO signaling are poorly understood. In the periphery, many effects of NO are mediated via the generation of the second messenger cyclic guanosine-3',5'-monophosphate (cGMP) and activation of the cGMP-dependent protein kinase type I (cGKI). However, previous studies suggested that the expression of cGKI in the nervous system is rather restricted, thus, questioning the functional significance of the cGMP/cGKI pathway as a mediator of NO signaling in the brain. Here we have performed a detailed immunohistochemical study to elucidate the distribution of cGKI in the CNS and eye of the mouse. Expression of cGKI protein was detected not only in the previously described areas (cerebellum, hippocampus, dorsomedial hypothalamus) but also in a number of additional regions, such as medulla, subcommissural organ, cerebral cortex, amygdala, habenulae, various hypothalamic regions, olfactory bulb, pituitary gland, and retina. Immunoblotting with isoform-specific antibodies indicated that the cGKIalpha isoform is prominent in the cerebellum and medulla, whereas the cGKIbeta isoform is predominant in the cortex, hippocampus, hypothalamus, and olfactory bulb. Similar levels of the isoforms were detected in the pituitary gland and eye. Thus, it appears that distinct brain regions express distinct cGKI isoforms that signal via distinct pathways. Together, these results improve our understanding of the cellular and molecular mechanisms of NO/cGMP/cGKI signaling and indicate that the distribution and functional relevance of this pathway in the mammalian brain is broader than previously thought.

Temporally controlled somatic mutagenesis in smooth muscle.

Ligand-dependent site-specific recombinases are powerful tools to engineer the mouse genome in specific somatic cell types at selected times during pre- and postnatal development. Current efforts are primarily directed towards increasing the efficiency of this recombination system in mice. We have generated transgenic mouse lines expressing a tamoxifen-activated Cre recombinase, CreER(T2), under the control of the smooth muscle-specific SM22 promoter. Both a randomly integrated transgene [SM-CreER(T2)(tg)] and a transgene that has been "knocked in" into the endogenous SM22 locus [SM-CreER(T2)(ki)] were expressed in smooth muscle-containing tissues. The level of CreER(T2) expression and tamoxifen-induced recombination was lower in SM-CreER(T2)(tg) mice compared with SM-CreER(T2)(ki) mice. Whereas no recombinase activity could be detected in vehicle-treated SM-CreER(T2)(ki) mice, administration of tamoxifen induced the excision of a loxP-flanked reporter transgene in up to 100% of smooth muscle cells. The recombined genome persisted for at least four months after tamoxifen treatment. SM-CreER(T2)(ki) transgenic mice should be useful to study the effects of various somatic mutations in smooth muscle.

X-linked congenital retinoschisis.

The natural history and electrophysiological findings of 52 patients with X-linked congenital retinoschisis with a follow-up of up to 26 years are described. The mean visual acuity was reduced to 0.24 +/- 0.2 and remained unchanged in most patients during this time. If visual loss occurred, it usually happened in the first decennium. The complications were retinal detachments in 11% and vitreous hemorrhages in 4% of the eyes. In general, the vitreous hemorrhages resolved spontaneously. Retinal detachments were treated successfully with conventional buckling procedures. Redetachments occurred in about 40%. Prophylactic laser coagulation was of no use because it was complicated by detachment in 43% of our series. The electro-oculogram was usually normal. In addition to the known electrorentinographic findings of normal a-wave and reduced b-wave amplitudes, we found prolonged b-wave latencies and implicit times, as well as a reduced 30 Hz flicker response.

[X-chromosomal congenital retinoschisis. Clinical aspects and electrophysiology]. / X-chromosomale kongenitale Retinoschisis. Klinik und Elektrophysiologie.

We evaluated retrospectively the clinical records and electrophysiological results of 52 patients suffering from X-linked congenital retinoschisis. Characteristic clinical findings were hyperopia (mean +2.3 +/- 3.1 D), reduced visual acuity (mean 0.24 +/- 0.2) and always macular pathology. Peripheral retinoschisis was present in 53% of the eyes. The natural course of the disease was normally stable. Complications were visual loss in 9.3%, vitreous hemorrhages in 4.7% and retinal detachments in 10.7% of the eyes. These complications generally occurred within the first decennium. Prophylactic laser coagulation was of no use because it was complicated by retinal detachment in 43% of our series. The electrooculogram was usually normal. In addition to the known electroretinographic findings of a low normal a-wave and reduced b-wave amplitudes, we found prolonged b-wave latencies and implicit times.

Criteria for selecting electrodes for electrical stimulation: theoretical and practical considerations.

Smaller, more charge-intensive electrodes are needed for "safe" stimulation of the nervous system. In this paper we review critical concepts and the state of the art in electrodes. Control of charge density and charge balance are essential to avoid tissue electrolysis. Chemical criteria for "safe" stimulation are reviewed ("safe" is equated with "chemically reversible"). An example of a safe, but generally impractical, charge-injection process is double-layer charging. The limit here is the onset of irreversible faradaic processes. More charge can be safely injected with so-called "capacitor" electrodes, such as porous intermixtures of Ta/Ta2O5. BaTiO3 has excellent dielectric properties and may provide a new generation of capacitor electrodes. Faradaic charge injection is usually partially irreversible since some of the products escape into the solution. With Pt, up to 400 muc/cm2 real area can be absorbed by faradaic reactions of surface-adsorbed species, but a small part is lost due to metal dissolution. The surface of "activated" Ir is covered with a multilayer hydrated oxide. Charge injection occurs via rapid valence change within this oxide. Little or no metal dissolution is observed, and gassing limits are not exceeded even under stringent conditions.

Electrical stimulation with Pt electrodes. V. The effect of protein on Pt dissolution.

The effect of protein on the charge-induced dissolution of Pt stimulation electrodes was studied in an in vitro system. Biphasic pulses (+/- 400 mA, +/- 400 microC cm-2 geom.) were applied to smooth Pt bead electrodes (surface area = 0.03-0.08 cm2) in a buffered saline solution containing 0.075-0.2 mg/ml human serum albumin; pulse solutions were analysed periodically for dissolved Pt by flameless atomic absorption spectrometry. The incorporation of protein in the pulse solution drastically altered the dissolution behaviour of Pt electrodes. Whereas dissolution in organic saline solutions proceeded essentially in a linear fashion, the rate in protein solution decreased with time and asymptotically approached zero. The passage of electric charge was required for the observed inhibition to develop but was not required to maintain it. In contrast, the constant presence of at least 0.15 mg/ml protein in the pulse solution was required for inhibition to develop and continue. Higher concentrations of protein did not enhance the observed inhibition. These findings bear favourably on the prospect for in vivo use of Pt stimulation electrodes: the dissolution process now appears to place no greater restriction on the acceptable pulse parameters than do other irreversible reactions such as H2O electrolysis.

Electrical stimulation with pt electrodes. IV. Factors influencing Pt dissolution in inorganic saline.

Trace analysis has shown that Pt electrodes can suffer appreciable dissolution when used to apply biphasic current pulses of the type used in neural stimulation. The dissolution occurs even under conditions where other irreversible faradaic reactions, e.g., H2O electrolysis, are avoided. In the present study, factors influencing the dissolution of Pt electrodes during biphasic pulsing in neutral inorganic saline have been examined. The findings are consistent with the behaviour of Pt electrodes reported in other inorganic media. In a given test, the quantity of Pt dissolved was found to be a linear function of the aggregate anodic or cathodic charge injected. Therefore, dissolution 'rates' can be conveniently expressed in terms of nanograms of Pt per coulomb injected, e.g., 100 ng C-1. Most of the Pt went into solution as Pt (II) species, so the above rate would correspond approximately to 100 p.p.m. of the anodic charge per pulse. For anodic-first (AF) pulses, charge density was the major factor controlling dissolution, whereas for cathodic-first (CF) pulses, pulse duration had the greater influence. Depending on the polarity (AF or CF), charge density, and duration of the biphasic pulse, the dissolution rate for smooth bead electrodes ranged from 30 to 300 ng C-1. Lower rates were achieved with platinized electrodes but in the absence of organic solutes, it is unlikely that Pt dissolution can be completely suppressed.

Electrical stimulation with Pt electrodes: Trace analysis for dissolved platinum and other dissolved electrochemical products.

A conservative requirement for 'safe' electrical stimulation is the absence of chemical changes adjacent to the stimulating electrodes. In electrochemical terms, this means that charge transfer processes producing dissolved species must be avoided. With this restriction, the aim of this study has been to establish the maximum charge density that can be passed during each half of a biphasic stimulation pulse. Possible dissolved species resulting from faradaic reactions at the Pt/saline interface include chloride oxidation products (ClO-, ClO3-, etc.) H+ or OH- ions and Pt ions. For balanced biphasic pulses, neither Cl- oxidation nor pH shifts appear likely to constitute significant problems and the most difficult problem to avoid appears to be metal dissolution. Pt dissolution has been monitored by UV spectrophotometric analysis and, because protein interferes with the analysis, the tests were run in inorganic saline solution. Results are presented in the form of nomographs which relate Pt dissolution to the charge density per pulse and the current density. Specific recommendations for minimizing Pt dissolution include the use of platinized electrodes, the restriction of charge densities per pulse to greater than or equal to 300 muC/geom cm2 of electrode surface, and preferably the use of cathodic-first biphasic pulses.