Clinical, gross morphological and neurochemical follow-up in normal, hydrocephalic and hydrocephalic-shunted rats.

The optimal time for treating congenital hydrocephalus is still unknown. The following study tries to answer this question by shunting hydrocephalic rats around the 10th day of life when the brain development corresponds to that of humans at birth. The animals were allocated to 4 groups: normal, hydrocephalic, normal sham-operated and hydrocephalic-shunted rats (groups 1-4). Body weight and neurological development was tested every 2nd-3rd day. X-rays of the skull were performed in groups 2, 3 and 4 at 10 days and in all at 20 days. In groups 2 and 4 0.1 ml lohexolum was instilled into the lateral ventricle at 10 days and in all at 20 days. X-rays were used to calculate the volume of the neurocranium and to identify ventriculomegaly and its grade (1-3). The x-rays and shunting were performed under general anesthesia, the latter using Kausch's technique. At 20 days of age the animals were sacrificed, the homogenized brain tissue was used to measure Protein, DNA, GAD and CNP by photometry, fluorometry and enzymatically. Time-course of neurological development in group 1: The locomotor patterns were attained gradually up to the ability to hold on to a bar. In group 2 there were larger variations and holding on to a bar was possible only in 6/13. In addition, a distinct tremor was observed in 34%. In group 4 holding on to a bar was possible in all, tremor was observed in 20% of examinations and diminishing following surgery. The volume of the neurocranium in groups 2 and 4 was significantly larger than in groups 3 at 10 days; and in group 2 significantly larger than in groups 1, 3 and 4 at 20 days. In group 4 the ventriculomegaly was distinctly reduced in 7 and remained the same in 1. Protein was significantly lower in group 4. DNA was the same in all groups. GAD was the lowest and the CNP significantly low in group 2. The study shows that an effective shunt may reverse the progressive clinical, radiological and neurochemical changes of hydrocephalus, and that surgery must not be performed necessarily earlier (e.g. prenatally in humans).

Nocardia farcinica sternotomy site infections in patients following open heart surgery.

Although Nocardia farcinica surgical site infection outbreaks have been reported (though rarely), no source for these has been identified. From May 1992 through June 1993, 5 patients contracted N. farcinica sternotomy site infections following open heart surgery at hospital A. A case-control study comparing case-patients (n=5) with open heart surgery patients without subsequent sternotomy site infections (n=50) identified as risk factors diabetes (4/5 vs. 11/50, P<.02) and exposure to a particular anesthesiologist (anesthesiologist A; 4/5 vs. 9/50, P<.01). Four case-patients' isolates and a hand isolate of anesthesiologist A had an identical ribotype pattern (strain 1); the remaining case-patient's isolate and multiple isolates from anesthesiologist A's hands and home had a different ribotype pattern (strain 2). An intensified hand-washing regimen, barriers (gloves, gowns), and cleaning of anesthesiologist A's house were associated with termination of the outbreak. This is the first reported nosocomial N. farcinica outbreak to document the source and person-to-person transmission epidemiologically and molecularly.

An outbreak of Enterobacter hormaechei infection and colonization in an intensive care nursery.

Enterobacter hormaechei was first identified as a unique species in 1989. Between 29 November 1992 and 17 March 1993, an outbreak of E. hormaechei occurred among premature infants in the intensive care nursery (ICN) at The Hospital of the University of Pennsylvania. The 10 infants whose cultures were positive for E. hormaechei (six were infected and four were colonized) had a lower median estimated gestational age and birth weight than did other ICN infants; other risk factors for infection or colonization with E. hormaechei were not identified. Cultures from three isolettes and a doorknob in the ICN were positive for E. hormaechei. Pulsed-field gel electrophoresis of isolates from six patients and two isolettes were identical. Observations of health care workers revealed breaks in infection control techniques that may have allowed transmission of this organism. We found that E. hormaechei is a nosocomial pathogen that can infect vulnerable hospitalized patients and that can be transmitted from patient to patient when infection control techniques are inadequate.

Status of tuberculosis infection control programs at United States hospitals, 1989 to 1992. APIC. Association for Professionals in Infection Control and Epidemiology.

BACKGROUND: Recent nosocomial outbreaks have raised concern about the risk of Mycobacterium tuberculosis transmission in United States hospitals. METHODS: To determine current tuberculosis (TB) infection control practices, we surveyed a sample of approximately 3000 acute care facilities about the number of patients with drug-susceptible or multidrug-resistant TB (MDR-TB), health care worker (HCW) tuberculin skin test (TST) results, and compliance with the 1990 Centers for Disease Control and Prevention (CDC) TB guidelines. Analyses were restricted to one response per hospital. RESULTS: Personnel at 1494 (49.8%) hospitals returned a completed survey. Respondent hospitals had a mean of 881 HCWs (range 8 to 10,000) and 196 (range 6 to 2450) beds; 62% percent were community nonteaching hospitals. Of respondent hospitals providing data for 1989 through 1992, the proportion that cared for patients with TB or MDR-TB increased from 46.4% to 56.6% and 0.8% to 4.5%, respectively. The pooled mean HCW TST positivity rate at hire rose from 0.95% to 1.14%, and the pooled mean HCW TST conversion rate increased from 0.40% to 0.51%. In 1992, when we compared hospitals with zero, one to five, or six or greater patients with TB, the risk of a positive HCW TST result at hire or at routine testing significantly increased with increasing number of patients with TB. From 1989 through 1992, the number of hospitals reporting the use of surgical masks for HCW respiratory protection decreased from 96.8% to 66.8%. In 1992, 66% of the hospitals reported compliance with four or more of the AFB isolation room criteria specified in the 1990 CDC TB guidelines. CONCLUSIONS: Contrary to prior surveys, this study shows that many U.S. community hospitals admit patients with TB less frequently than do teaching hospitals, and infrequently admit patients with MDR-TB. Because the risk of HCW TST conversion varies with hospital characteristics, these data show the importance of performing a risk assessment, as recommended in the CDC TB guidelines, for each ward and hospital so that TB control measures can be individualized.

Control of nosocomial transmission of multidrug-resistant Mycobacterium tuberculosis among healthcare workers and HIV-infected patients.

From 1988 to 1990, an outbreak of multidrug-resistant tuberculosis (MDR-TB) among patients, and an increased number of tuberculin-skin-test conversions among healthcare workers, occurred on the HIV ward of Jackson Memorial Hospital, Miami, Florida, USA. Measures similar to those subsequently recommended in the 1990 Centers for Disease Control and Prevention guidelines were implemented on the HIV ward by June, 1990, and in September, 1992, we evaluated the efficacy of these control measures. Among MDR-TB patients and healthcare workers with tuberculin-skin-test conversions on the HIV ward, we looked for evidence of exposure to HIV ward MDR-TB patients positive for acid-fast bacilli in sputum during initial (January-May, 1990) and follow-up (June, 1990-June, 1992) periods. Exposure before implementation of control measures to an infectious MDR-TB patient on the HIV ward was recorded in 12 of 15 (80%) MDR-TB patients during the initial period and 5 of 11 (45%) MDR-TB patients during follow-up. After implementation of control measures, no episodes of MDR-TB could be traced to contact with infectious MDR-TB patients on the HIV ward. Skin-test conversions among workers on the HIV ward declined from 7 of 25 (28%) during the initial period to 3 of 17 (18%) in the early (June, 1990-February, 1991) and 0 of 23 in the late (March, 1991-June, 1992) follow-up periods (p < 0.01). Skin-test conversions among healthcare workers were not associated with increased exposure to MDR-TB patients, and were not significantly higher among workers on the HIV ward than on a control ward without tuberculosis patients (3/27 vs 0/16). These data demonstrate that implementation of measures similar to the Centers for Disease Control and Prevention 1990 tuberculosis-control guidelines were effective in halting transmission of MDR-TB to healthcare workers and HIV-infected patients.

Patient cytokine response in transfusion-associated sepsis.

Cytokine concentrations in plasma from patients transfused with packed erythrocytes contaminated with gram-negative bacilli were measured. Cytokine concentrations in posttransfusion plasma were significantly elevated. A difference in cytokine patterns between survivors and a nonsurvivor was observed.

Purification of lentil lectins using preparative electrophoresis.

Electrophoresis presents an interesting alternative to chromatography for the purification of biological compounds. To document the performance of three preparative electrophoresis apparatus currently available, they were applied to the purification of lectins from lentil seeds which contain two isolectins usually purified by chromatography. Purification by electrophoresis consists of first isolating a mixture of the two isolectins and then separating them. For the first step, either of two free-flow electrophoresis apparatus were employed: the Elphor VaP 22, using field step electrophoresis and the Biostream using zone electrophoresis. To optimize the process, the Biostream was modified to a recycling mode. This required repositioning one dialysis membrane which separates an electrode from the separation chamber. This allowed the lentil extract to be desalted by electrodialysis directly in the apparatus prior to fractionation. A high concentration of lectins was collected at the cathode and acidic proteins were collected at the anode. The bulk of the extract was recycled until the whole volume was processed. In a second step the isolectins were separated by recycling isoelectric focusing in the recycling isoelectric focusing apparatus. The present work clearly demonstrates that electrophoretic methods provide lectins with higher purity than chromatographically purified commercial products.

Amphoteric, isoelectric immobiline membranes for preparative isoelectric focusing.

Amphoteric, isoelectric agarose membranes, as devised by Martin and Hampson [Martin, A.J.P. and Hampson, F. (1978) J. Chromatogr. 159, 101-110], are found unsuitable for blocking electroendosmosis in multi-compartment electrolysers during preparative isoelectric focusing, due to the poor and highly unpredictable incorporation of carboxyls and amino groups on the polysaccharide moiety. New, polyacrylamide-based membranes are described, containing as buffers and titrants the Immobiline chemicals used to produce immobilized pH gradients. These new membranes are supported on both faces by a non-woven polypropylene cloth, a material exhibiting minimal adsorption properties for proteins. Due to the extensively developed Immobiline technology, membranes with highly predictable isoelectric points, well-defined buffering capacity and conductivity can be synthesized at any pH value along the pH 3-10 scale. They are effective in blocking electroendosmosis even when the delta pH on either side of the membrane is as high as 1.5 pH unit.

Isoelectric focusing using non-amphoteric buffers in free solution: I. Determination of stable concentration profiles.

For large-scale separations of proteins, the use of simple non-amphoteric buffers in free solution and in multicompartment electrolyzers seems promising for industrial applications. The stabilization of a pH profile with this type of buffer requires the strict observation of two conditions: choice of an adequate buffer; stationary profiles of concentrations. During electrolysis in free solution, the ions of the buffer are displaced across the compartments by migration and by diffusion. To keep a stationary composition, the inflow and outflow of all individual ionic species through each compartment must be identical. At high current, diffusion may be neglected against migration and the ionic flows will be identical if the transport number of each ion is constant at each location within the cell. In these conditions, stationary compositions will be independent of the electric current. This condition of constant transport numbers implies the use of profiles of buffer concentrations different from those published up to now. The new equations for these profiles of concentrations are given in the present paper. The constant migration of the ions must be compensated in the end compartments of the isoelectric focusing cell to provide a stable steady state. Two methods are proposed in the literature: the buffer renewal method and the external recycling method (rheoelectrolysis). Here modified buffer renewal method is proposed. Using stationary mass balances, analytical equations are given to calculate the flows and the composition of the solutions to be recycled or added. Using these equations and the profiles of concentrations to keep constant transport numbers, it is demonstrated that only a renewal of the buffers in the end compartments may lead to stable pH profiles and thus to valid conditions of separation.

Isoelectric focusing using non-amphoteric buffers in free solution: II. Apparatus and measures of pH stability.

Isoelectric focusing of amino acids or proteins requires a time-invariant pH gradient. The maintenance, in an electric field, of such profiles with simple non-amphoteric buffers is possible in multicompartment cells using well determined concentration profiles. The method for determining these concentration profiles has been proposed in a preceding paper. A multicompartment cell has been built for the purpose of verifying the assumptions made. The technical characteristics of this cell will be described here. The time-stability of pH profiles obtained with sodium acetate/acetic acid buffers has been measured for concentration profiles determined so as to keep constant the transport number of each ion throughout the cell. Measured over a time span of 10 h and with a current density of 96 mA cm-2, the pH shift is, in the worst case, 0.009 pH unit/h. This corresponds to a much better stability than the one obtained with a constant concentration of sodium acetate in all compartments, and justifies the chosen concentration profiles based on the condition of constant transport numbers. The above mentioned method for the computation of the buffer concentration assumed a constant relative mobility of the ions. The experiments have shown the limits of this assumption, i.e. the variation of ionic mobilities with the ionic strength and the temperature diminishes the stability of the pH gradient. However, slight adjustments of the concentration in the end compartments allow some improvement of the stability. If the temperature could be precisely controlled in each compartment, a better pH stability than what has been achieved in these experiments should be reached. Two methods of compensation of the migration of ions in the end compartments (buffer renewal method and external recycling method) have been tested and will be discussed.

Isoelectric focusing using non-amphoteric buffers in free solution: III. Separation of amino acids.

Separation of proteins or amino acids by isoelectric focusing in multicompartment devices has been proposed for large-scale purifications of biological mixtures. In the perspective of industrial applications, the present authors built a multicompartment apparatus and studied the pH profiles stabilized by simple non-amphoteric buffers (acetic acid and sodium acetate). Mixtures of two amino acids were separated to test this device. A theoretical model comprising one dimensionless separation parameter is proposed to characterize these separations. This model allows one to calculate the purity of the recovered amino acids, the yield of a separation at steady-state or the time necessary to obtain a given concentration of an amino acid in one of the compartments of the isoelectric focusing cell. The separation parameter contains the physical parameters which intervene in the electric migration and in the diffusion. Values of this separation parameter have been experimentally determined for three amino acids under various experimental conditions. The results confirm the usefulness of this model in designing a multicompartment isoelectric focusing apparatus.