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B M Block

Publications and source records attributed to B M Block.

10 recordsLinked to original sources
PubMed2000

Use of intensive care-specific interventions in major teaching and other hospitals: a regional comparison.

OBJECTIVE: To compare the use of 40 specific medical interventions in intensive care units (ICUs) of major teaching and other hospitals DESIGN: Retrospective cohort study. SETTING: Thirty-eight ICUs in 28 hospitals in a large metropolitan region. PATIENTS: A total of 12,929 consecutive eligible admissions to medical, surgical, neurologic, or mixed medical/surgical ICUs between January 1, and June 30, 1994. MEASUREMENTS: The use of 40 diagnostic and therapeutic interventions during the first 24 hrs of ICU admission were obtained from patient medical records and a weighted intervention score was determined for each patient. Admission severity of illness was measured by using the Acute Physiology and Chronic Health Evaluation III methodology. MAIN RESULTS: Patients at the five teaching hospitals had a greater severity of illness (mean predicted risk of in-hospital death, 15.1%+/-21.9% vs. 11.2%+/-19.0%; p < .01) than patients at the 23 other hospitals. Patients at major teaching hospitals also had higher mean intervention scores (3.5+/-4.9 vs. 2.3+/-3.7; p < .01). Differences in intervention scores persisted after controlling for severity of illness, admission diagnosis, and admission source. However, scores varied among the major teaching hospitals. When examined individually, only three of the five major teaching hospitals had higher (p < .05) interventions scores, compared with other hospitals, whereas one had a lower (p < .05) intervention score. CONCLUSIONS: Patients in ICUs at major teaching hospitals were, in aggregate, more likely to receive diagnostic and therapeutic interventions than patients at other hospitals. Variation among major teaching hospitals suggests that factors other than teaching status also affect the use of these interventions.

APACHE↗
PubMed1998

Surface charge and lanthanum block of calcium current in bullfrog sympathetic neurons.

The density of surface charge associated with the calcium channel pore was estimated from the effect of extracellular ionic strength on block by La3+. Currents carried by 2 mM Ba2+ were recorded from isolated frog sympathetic neurons by the whole-cell patch-clamp technique. In normal ionic strength (120 mM N-methyl-D-glucamine, NMG), La3+ blocked the current with high affinity (IC50 = 22 nM at 0 mV). La3+ block was relieved by strong depolarization in a time- and voltage-dependent manner. After unblocking, open channels reblocked rapidly at 0 mV, allowing estimation of association and dissociation rates for La3+: k(on) = (7.2 +/- 0.7) x 10(8) M(-1) s(-1), k(off) = 10.0 +/- 0.5 s(-1). To assess surface charge effects, La3+ block was also measured in low ionic strength (12.5 mM NMG) and high ionic strength (250 mM NMG). La3+ block was higher affinity and faster by two- to threefold in 12.5 mM NMG, with little effect of 250 mM NMG. The data could be described by Gouy-Chapman theory with a surface charge density of approximately 1 e-/3000-4000 A2. These results indicate that there is a small but detectable surface charge associated with the pore of voltage-dependent calcium channels.

Animals↗
PubMed1997

Delayed rectifier current of bullfrog sympathetic neurons: ion-ion competition, asymmetrical block and effects of ions on gating.

1. The delayed rectifier (DR) K+ channel pore was probed using different permeant and blocking ions applied intra- and extracellularly. Currents were recorded from bullfrog sympathetic neurons using whole-cell patch-clamp techniques. 2. With intra- and extracellular Cs+ (0 K+), there were large, tetraethylammonium (TEA)-sensitive currents. Adding K+ back to the extracellular solution revealed that the current with Cs+i was K+ selective (permeability ratio PCs/PK = 0.17 +/- 0.02, n = 4) and showed a strong anomalous mole fraction effect. 3. There were also large non-inactivating currents with Na+i and Na+o (0 K+). The current with Na+i was K+ selective (Na+o vs. K+o: PNa/PK = 0.022 +/- 0.005, n = 5), and was TEA sensitive with K+o but not with Na+o. 4. Permeant ions affected gating kinetics. DR currents activated faster in K+ than in Cs+, and activated faster with increasing concentrations of either K+ or Cs+. Deactivation was slowed by increased K+ or Cs+ concentration, with no difference between K+ and Cs+. 5. The pore was also characterized using intracellular blocking ions. A wide variety of monovalent cations (TEA, N-methyl-D-glucamine, arginine, choline, CH3NH3+, Li+, Cs+ and Na+) blocked DR channels from the inside in a voltage-dependent manner: KD at 0 mV was 2.9 mM for TEA and 134-487 mM for the others, at apparent electrical distances (delta) of 0.33-0.79. There was no detectable block by 10 mM Mgi2+. Apart from TEA, the organic cations did not block from the outside. 6. The permeability to Na+ in the absence of K+, and the strong anomalous mole fraction effects observed for Cs+o + K+o mixtures, suggest that DR channels select for K+ using ion-ion competition. The block by large intracellular cations shows that the pore is asymmetrical. The loss of high affinity TEAo block with Na+i and Na+o, and the effects of permeant ions on gating, suggest that channel conformation may be affected by ions in the pore.

Animals↗
PubMed1996

Ion permeation and block of M-type and delayed rectifier potassium channels. Whole-cell recordings from bullfrog sympathetic neurons.

Ion permeation and conduction were studied using whole-cell recordings of the M-current (I(M)) and delayed rectifier (IDR), two K+ currents that differ greatly in kinetics and modulation. Currents were recorded from isolated bullfrog sympathetic neurons with 88 mM [K+]i and various external cations. Selectivity for extracellular monovalent cations was assessed from permeability ratios calculated from reversal potentials and from chord conductances for inward current. PRb/PK was near 1.0 for both channels, and GRb/GK was 0.87 +/- 0.01 for IDR but only 0.35 +/- 0.01 for I(M) (15 mM [Rb+]o or [K+]o). The permeability sequences were generally similar for I(M) and IDR: K+ approximately Rb+ > NH4+ > Cs+, with no measurable permeability to Li+ or CH3NH3+. However, Na+ carried detectable inward current for IDR but not I(M). Nao+ also blocked inward K+ current for IDR (but not IM), at an apparent electrical distance (delta) approximately 0.4, with extrapolated dissociation constant (KD) approximately 1 M at 0 mV. Much of the instantaneous rectification of IDR in physiologic ionic conditions resulted from block by Nao+. Extracellular Cs+ carried detectable inward current for both channel types, and blocked I(M) with higher affinity (KD = 97 mM at 0 mV for I(M), KD) approximately 0.2 M at 0 mV for IDR), with delta approximately 0.9 for both. IDR showed several characteristics reflecting a multi-ion pore, including a small anomalous mole fraction effect for PRb/PK, concentration-dependent GRb/GK, and concentration-dependent apparent KD's and delta's for block by Nao+ and Cso+. I(M) showed no clear evidence of multi-ion pore behavior. For I(M), a two-barrier one-site model could describe permeation of K+ and Rb+ and block by Cso+, whereas for IDR even a three-barrier, two-site model was not fully adequate.

Animals↗
PubMed1992

Aminophylline increases submaximum power but not intrinsic velocity of shortening of frog muscle.

We hypothesized that methylxanthines, such as aminophylline, increase the power developed by submaximally activated frog skeletal muscles by increasing the force developed at any given velocity of shortening. Frog semitendinosus muscles were excised and tested at 20 degrees C in oxygenated control and aminophylline Ringer solutions. Force-velocity relationships were determined and power was calculated from muscles stimulated at frequencies of 80 and 300 Hz. The 300-Hz frequency of stimulation produced a maximum rate of force development. In 50 and 500 microM aminophylline, twitch force increased by 25 +/- 12 and 75 +/- 13%, respectively. Aminophylline did not affect maximum isometric force generation or the shortening velocity at any relative load. At 80-Hz stimulation and in the presence of 500 microM aminophylline, power increased by an average of 11% at 10 of 14 relative loads. At maximum frequencies of stimulation, aminophylline had no effect on any measured parameter. We conclude that aminophylline increases the power developed by submaximally activated frog muscles through an increase in the force generated particularly at the lower velocities of shortening.

Aminophylline↗
PubMed1991

American Association for Partial Hospitalization Child and Adolescent Special Interest Group: standards for child and adolescent partial hospitalization programs.

This article describes standards and guidelines for the treatment of children and/or adolescents in partial hospitalization programs. Developed through the Child and Adolescent Special Interest Group of the American Association of Partial Hospitalization, they are intended to aid in the establishment of quality treatment programs.

Adolescent↗
PubMed1990

State statute reference concerning partial hospitalization, 1988.

A survey process was begun in 1983 collecting and examining state statutes governing Partial Hospitalization programs. Data were collected from 37 states and the Country of Canada, which were then analyzed into the categories of definition, goals, target population, length of stay, frequency of patient participation, duration of a program day, program services, staffing, and documentation and quality assurance. The results revealed a great diversity of the operationalization of the treatment modality of partial hospitalization through state statutes. There is a clear need for increased levels of clarity and uniformity of this treatment mode.

Canada↗
PubMed1978

Silver stain reveals nucleolus organizer regions on a satellited Yq chromosome.

Chromosomes from a patient with a satellited Yq were stained with a silver procedure that differentially stains nucleolus organizer regions. The Yqs stained heavily in all cells examined, indicating the presence of ribosomal cistrons at this region. The Yqs also entered into satellite associations with the D and G group chromosomes at a frequency greater than would be expected through chance.

Azure Stains↗
PubMed1977

Visualization of centriole-bodies using silver stain.

Duplicate staining of human metaphase chromosomes, first with Giemsa followed by silver, revealed the presence of two small silver-stained bodies not seen in the Giemsa stained metaphases. Similar bodies were subsequently found in the metaphases of several animal groups. The size, structure, spatial relationships to the nucleus, behavior throughout the cell cycle, and apparent universal presence of these bodies suggest that they are either centrioles or associated centriolar structures. These centriole-bodies can be seen throughout the cell cycle, even in hypotonically spread C-metaphase chromosome plates. The silver stain procedure allows enough resolution to distinguish parent and daughter centriole-bodies at interphase, thus permitting visualization of the replication, maturation and separation stages of these bodies with the light microscope.

Animals↗