F-waves--physiology and clinical uses.

F-waves are low amplitude responses produced by antidromic activation of motoneurons. They may not appear after each stimulus and are inherently variable in latency, amplitude, and configuration. Meaningful analysis of F-waves requires an appreciation of these characteristics of F-waves as well as an understanding of their physiology.

Theoretical model and Rasch analysis to develop a revised Foot Function Index.

Background: The Foot Function Index (FFI) is a widely used self-reported measure of health-related foot function. Several areas have been identified for potential improvement, and this study responds to such criticisms. The objectives of this study were to: (1) develop a theoretical model of foot functioning, (2) develop a revised FFI (FFI-R), and (3) field-test the FFI-R.

Progression of kidney disease in type 2 diabetes - beyond blood pressure control: an observational study.

Background: The risk factors for progression of chronic kidney disease (CKD) in type 2 diabetes mellitus (DM) have not been fully elucidated. Although uncontrolled blood pressure (BP) is known to be deleterious, other factors may become more important once BP is treated.

Methods: All patients seen in the outpatient clinics of our hospital between January 1993 and September 2002 with type 2 DM and clinical evidence of CKD were evaluated.

Comparison of automated and manual F-wave latency measurements.

Objective: F-waves are well-established clinical neurophysiological studies. F-wave analysis is now cumbersome limiting the usefulness of F-waves. This study evaluates the accuracy and reliability of an automated analysis method for F-wave latencies.

Effect of lung volume reduction surgery on diaphragmatic neuromechanical coupling at 2 years.

Study Objectives: We previously reported that patients with emphysema show an increase in diaphragmatic neuromechanical coupling at 3 months after lung volume reduction surgery. Diaphragmatic neuromechanical coupling was quantified as the quotient of tidal volume (normalized to total lung capacity) to tidal change in transdiaphragmatic pressure (normalized to maximal transdiaphragmatic pressure). As such, neuromechanical coupling estimates the fraction of diaphragmatic capacity used to generate tidal breathing.

Mechanism of increased angiotensin II levels in glomerular mesangial cells cultured in high glucose.

Previous studies have shown that glucose increases angiotensin II (AngII) levels in rat glomerular mesangial cells and that AngII mediates the inhibitory effects of high glucose on matrix degradation in these cells. The present study addresses the following questions: (1) What are the mechanisms for the generation of AngII in mesangial cells? (2) What are the effects of glucose on AngII generation by these mechanisms? Experiments employed primary mesangial cells from normal Sprague-Dawley rats. The levels of immunoreactive angiotensinogen (AGT), angiotensin I (AngI), and angiotensin II (AngII) were measured by ELISA.

Can diaphragmatic contractility be assessed by airway twitch pressure in mechanically ventilated patients?

Background: In critically ill patients inspiratory muscle function may be assessed by measurements of maximal inspiratory airway pressure and the response of twitch transdiaphragmatic pressure (Pdi tw) to bilateral phrenic nerve stimulation. The first is limited by its total dependence on patient cooperation. Although the second approach is independent of patient volition, it is impractical because it requires oesophageal and gastric balloons.

Equipment needs for noninvasive mechanical ventilation.

Noninvasive mechanical ventilation (NIV) has a long tradition for the treatment of chronic respiratory failure and more recently has also been applied in acute respiratory failure. Based on this experience both critical care ventilators and portable ventilators are used to perform NIV. The individual choice of ventilator type should depend on the patient's condition and also on the expertise of attending staff, therapeutic requirements and the location of care.

Selecting an accessory device with a metered-dose inhaler: variable influence of accessory devices on fine particle dose, throat deposition, and drug delivery with asynchronous actuation from a metered-dose inhaler.

Accessory devices reduce common problems with metered-dose inhalers (MDIs), namely high oropharyngeal deposition of aerosol and incoordination between actuation and inhalation by the patient. The objective of this study was to systematically compare the performance of various accessory devices in vitro. MDIs were tested alone or in combination with four spacers (Toilet paper roll, Ellipse, Optihaler, Myst Assist) and five holding chambers (Aerochamber, Optichamber, Aerosol Cloud Enhancer, Medispacer, and Inspirease).

The voluntary drive to breathe is not decreased in hypercapnic patients with severe COPD.

How do the respiratory centres of patients with chronic obstructive pulmonary disease (COPD) and hypercapnia respond to acute increases in inspiratory load? A depressed respiratory motor output has long been postulated, but studies on this issue have yielded inconsistent results, partly due to limitations of investigative techniques. Many of these limitations can be overcome by the twitch interpolation technique, which is capable of accurately quantifying the degree of diaphragmatic activation, termed the voluntary drive to breathe. The hypothesis that patients with COPD and hypercapnia compensate for an acute increase in mechanical load on the inspiratory muscles with a lower voluntary drive to breathe than is the case with normocapnic patients was tested.

Dr. Gottlieb Burckhardt--the pioneer of psychosurgery.

The first attempt at psychosurgery--intentional damage to the intact brain for the relief of mental illness--was undertaken in 1888 by the Swiss psychiatrist Gottlieb Burckhardt. Six chronic schizophrenic patients underwent localized cerebral cortical excisions. Most patients showed improvement and became easier to manage, although one died from the procedure and several had aphasia or seizures.

Improvement in aerosol delivery with helium-oxygen mixtures during mechanical ventilation.

In mechanically ventilated patients with airway obstruction, helium-oxygen (He-O2) mixtures reduce airway resistance and improve ventilation, but their influence on aerosol delivery is unknown. Accordingly, we determined the effect of various He-O2 mixtures on albuterol delivery from metered-dose inhalers (MDIs) and jet nebulizers in an in vitro model of mechanical ventilation. Albuterol delivery from a MDI was increased when the ventilator circuit contained 80% helium and 20% oxygen (He-O2 80/20) versus O2: 46.

Pulse oximetry.

Pulse oximetry is one of the most commonly employed monitoring modalities in the critical care setting. This review describes the latest technological advances in the field of pulse oximetry. Accuracy of pulse oximeters and their limitations are critically examined.

Effect of isocapnic hypoxia on variational activity of breathing.

In the presence of either hypocapnia or sleep, hypoxia has been shown to induce periodic breathing and increase the total variational activity of breath components. It is not known whether hypoxia induces alterations in breathing variability during wakefulness and in the absence of hypocapnia. To address this issue, we studied nonobtrusively 14 healthy awake subjects before and during the delivery of a hypoxic gas mixture via a plastic hood; the subjects' oxygen saturation decreased from 98 to 79% and end-tidal carbon dioxide tension was kept constant.

Research on the quality of life of lung transplant candidates and recipients: an integrative review.

Although lung transplantation is one of the most rapidly growing areas of solid organ transplantation, there has been little research on the quality of life of lung transplant candidates or recipients. This review critiques and synthesizes the quality-of-life reports concerning these patients that have been published between January 1980 and January 1999. The purposes of this review of the literature were to (1) examine both the conceptual and operational definitions of quality of life used; (2) identify and list the instruments used to measure quality of life; (3) investigate methodologic issues; and (4) determine the state-of-the-art of research in this area.

Is dipalmitoylphosphatidylcholine a substrate for convertase?

Convertase has homology with carboxylesterases, but its substrate(s) is not known. Accordingly, we determined whether dipalmitoylphosphatidylcholine (DPPC), the major phospholipid in surfactant, was a substrate for convertase. We measured [(3)H]choline release during cycling of the heavy subtype containing [(3)H]choline-labeled DPPC with convertase, phospholipases A(2), B, C, and D, liver esterase, and elastase.

Does inhaled albuterol improve diaphragmatic contractility in patients with chronic obstructive pulmonary disease?

We tested the hypothesis that the decrease in dyspnea in patients with COPD with inhaled albuterol is in part due to increased diaphragmatic contractility. Eleven patients with COPD inhaled albuterol or placebo in a double-blind randomized manner. Subsequently, dyspnea was measured while patients breathed through inspiratory resistors, and diaphragmatic contractility was quantified during maximal inspiratory efforts and after twitch stimulation of the phrenic nerves.

Multi-institutional study of the angiogenesis inhibitor TNP-470 in metastatic renal carcinoma.

Purpose: Renal cell carcinoma is resistant to most chemotherapy, and only a minority of patients respond to immunotherapy. Its highly vascular nature suggests that antiangiogenesis therapy might be useful. We thus performed a phase II study of the fumigillin analog TNP-470 in previously treated patients with metastatic renal cell carcinoma.

Advances in respiratory monitoring during mechanical ventilation.

This review provides an update on the various techniques that are available to monitor patients during mechanical ventilation with an emphasis on clinical observations and applications in critically ill patients.

Decreased glomerular proteinase activity in the streptozotocin diabetic rat.

Decreased glomerular proteinase activity may contribute to matrix accumulation in diabetes. Male Sprague-Dawley rats were rendered diabetic by injection of streptozotocin (STZ) 65 mg/kg i.v.

Influence of phospholipid composition on the properties of reconstituted surfactants.

The influence of phospholipids on the ultrastructure and metabolism of reconstituted surfactants has not been well defined. The aim of this study was to determine if changes in the phospholipid composition of reconstituted surfactants altered their biophysical properties, ultrastructure, and conversion to light subtype by cycling. We prepared various surfactants containing radiolabeled dipalmitoylphosphatidylcholine ([14C]DPPC).