Incidence, predictors, and outcome of intermediate syndrome in cholinergic insecticide poisoning: a prospective observational cohort study.

CONTEXT: Clinical manifestations and outcome of cholinergic insecticide poisoning is well studied. There are limited data on neuroparalytic features, predictors, and impact on mortality of intermediate syndrome. METHODS: Patients admitted with history of insecticide exposure and cholinergic signs in a tertiary care center between April 2011 and March 2012 were followed up till recovery or death. While on standard care, development of intermediate syndrome was noted by neck and proximal muscle weakness, and/or signs of respiratory failure in the absence of cholinergic signs. RESULTS: In 176 patients studied, incidence of intermediate syndrome was 17.6% (n = 31) with mean time of appearance of 44.5 ± 22.1 h after exposure (range 26 h- 5 days). Intermediate syndrome occurred in organophosphorus and carbamate poisoning (38.7% and 41.9%) and lasted for 1-7 days. All patients with intermediate syndrome developed weakness of neck and proximal muscles during the course; neck muscle weakness was the initial feature in majority of patients with respiratory failure (20/26). Age ≥ 45 (RR 2.23, 95% CI 1.14-4.38, p = 0.02), and dimethyl organophosphorus compounds (RR 4.87, 95% CI 1.82-13.04, p = 0.01) were found to be associated with development of intermediate syndrome while multiple gastric lavage was protective (RR 0.44, 95% CI 0.22-0.87, p = 0.001). Receiver operating characteristic curves were plotted for International Program on Chemical Safety Poison Severity Score (IPCS PSS) and Glasgow coma scale (GCS) on admission (AUC/sensitivity/specificity 0.77/0.94/0.6 for IPCS PSS > 2 and 0.64/0.71/0.65 for GCS ≤ 10). Overall mortality was 28.4% (n = 50); 40% (n = 20/50) occurred among intermediate syndrome patients with respiratory failure. CONCLUSION: As with exposure to organophosphorus, carbamate also result in intermediate syndrome; risk may be high with age ≥ 45, admission score of PSS > 2, and GCS ≤ 10. It can be detected early by identifying neck muscle weakness which aids in anticipating respiratory failure. Multiple gastric lavages may be protective; needs larger studies for clarification.

RhoA-Rho kinase and platelet-activating factor stimulation of ovine foetal pulmonary vascular smooth muscle cell proliferation.

OBJECTIVES: Platelet-activating factor (PAF) is produced by pulmonary vascular smooth muscle cells (PVSMC). We studied effects of Rho kinase on PAF stimulation of PVSMC proliferation in an attempt to understand the role of RhoA/Rho kinase on PAF-induced ovine foetal pulmonary vascular remodelling. Our hypothesis is that PAF acts through Rho kinase, as one of its downstream signals, to induce arterial (SMC-PA) and venous (SMC-PV) cell proliferation in the hypoxic lung environment of the foetus, in utero. MATERIALS AND METHODS: Rho kinase and MAPK effects on PAF receptor (PAFR)-mediated cell population expansion, and PAFR expression, were studied by DNA synthesis, western blot analysis and immunocytochemistry. Effects of constructs T19N and G14V on PAF-induced cell proliferation were also investigated. RESULTS: Hypoxia increased PVSMC proliferation and Rho kinase inhibitors, Y-27632 and Fasudil (HA-1077) as well as MAPK inhibitors PD 98059 and SB 203580 attenuated PAF stimulation of cell proliferation. RhoA T19N and G14V stimulated cell proliferation, but co-incubation with PAF did not affect proliferative effects of the constructs. PAFR protein expression was significantly downregulated in both cell types by both Y-27632 and HA-1077, with comparable profiles. Also, cells treated with Y-27632 had less PAF receptor fluorescence with significant disruption of cell morphology. CONCLUSIONS: Our results show that Rho kinase non-specifically modulated PAFR-mediated responses by a translational modification of PAFR protein, and suggest that, in vivo, activation of Rho kinase by PAF may be a further pathway to sustain PAFR-mediated PVSMC proliferation.

Ion-specific protein destabilization of the contractile proteins of cardiac muscle fibers.

We investigated the inhibitory effects of increased salt concentrations on maximal calcium-activated force (Fmax) of rabbit cardiac papillary muscle bundles skinned with Triton X-100. While other studies have reported a lack of ion-specific effects on Fmax of cardiac muscle, we clearly demonstrated the presence of such effects when a wider variety of salts was investigated. In addition, like skeletal muscle, cardiac muscle was found to be sensitive to ionic strength and not to ionic equivalence. In support of our hypothesis that the ion-specific effects are due to protein destabilization, we found that a protein stabilizer (trimethylamine N-oxide, TMAO) completely abolished the ion-specific effects on Fmax. The ion-specific effect is probably due to binding of ions to the contractile proteins. The general ionic effect is most likely due to electrostatic shielding that remains in the presence of TMAO. Neither 300 mM sucrose nor TMAO significantly altered Fmax at physiological ionic strength indicating that the ion-specific depression of Fmax was not due to a colligative/osmotic effect. Furthermore, adding sucrose to solutions with a supraphysiological ionic strength caused a further decrease in Fmax indicating that certain osmolytes can alter Fmax if the contractile proteins are initially destabilized.

Influence of physiological L(+)-lactate concentrations on contractility of skinned striated muscle fibers of rabbit.

These experiments investigated the effects of physiological concentrations of L(+)-lactate on the contractility of chemically skinned rabbit fast-twitch psoas, slow-twitch soleus, and cardiac muscles at pH 7.L(+)-Lactate depressed maximal calcium-activated force (Fmax) of all muscles studied within the range of 5-20 (slow-twitch muscle) or 5-25 mM (fast-twitch and cardiac muscles). Fmax of fast-twitch fibers was inhibited to the greatest degree (9% in K2 creatine phosphate solutions). In all of these muscle types, Fmax returned to control levels as L(+)-lactate was increased to 30-50 mM. Substitution of neither D-lactate nor propionate for L(+)-lactate significantly altered Fmax. In addition, with the exception of fast-twitch muscle (where the Hill coefficient decreased), L(+)-lactate concentrations, which maximally inhibited Fmax, did not affect the force vs. pCa relationship of muscles tested. These results demonstrate that L(+)-lactate significantly contributes to the depression of muscle function noted during lactic acidosis, directly inhibiting Fmax of the contractile apparatus. This contribution is maximal in fast-twitch muscle where L(+)-lactate is responsible for as much as one-third of the depressant effect on Fmax of the contractile apparatus noted during lactic acidosis.

Systemic concepts in speech-language treatment.

While systemic concepts are well known in many professions, a systemic paradigm is relatively new to most speech-language pathologists. Five systems concepts that apply to current practices in speech-language pathology are described and illustrated. The concepts relate to the influences of context or environment, relationships, family structure, isomorphism, and the attribution of meaning.

Influence of ionic strength on contractile force and energy consumption of skinned fibers from mammalian and crustacean striated muscle.

Increased ionic strength decreases maximal calcium-activated force (Fmax) of skinned muscle fibers via mechanisms that are incompletely understood. In detergent-skinned fibers from either rabbit (psoas) or lobster (leg or abdomen), Fmax in KCl-containing solutions was less than in potassium methanesulfonate (KMeSO3), which we showed previously was the least deleterious salt for adjusting ionic strength. In either salt, lobster fibers were considerably less sensitive to elevated ionic strength than rabbit fibers. Trimethylamine N-oxide (TMAO, a zwitterionic osmolyte found in high concentration in cells of salt-tolerant animals) increased Fmax, especially in high KCl solutions. In this regard, TMAO was more effective than a variety of other natural or synthetic zwitterions. In rabbit fibers, increasing ionic strength decreases Fmax but has little effect on contractile ATPase rate measured simultaneously using a linked-enzyme assay. Thus high salt increases the tension-cost of contraction (i.e. ratio ATPase/Fmax). At both high and low salt, TMAO decreases tension-cost. Given a simple two-state model of the cross-bridge cycle, these data indicate that ionic strength and TMAO affect the apparent detachment rate constant. High ionic strength KCl solutions extract myosin heavy- and light-chains, and troponin C from rabbit fibers. This extraction is virtually abolished by TMAO. Natural zwitterions, such as TMAO, have been shown to protect proteins against destabilization by high salt or other denaturatants. Our data indicate that, even in the best of salts, destabilization of the actomyosin complex may play a role in the effect of high ionic strength on the contractile process.

Ion-specific and general ionic effects on contraction of skinned fast-twitch skeletal muscle from the rabbit.

We used single fibers from rabbit psoas muscle, chemically skinned with Triton X-100 nonionic detergent, to determine the salts best suited for adjusting ionic strength of bathing solutions for skinned fibers. As criteria we measured maximal calcium-activated force (Fmax), fiber swelling estimated optically, and protein extraction from single fibers determined by polyacrylamide gel electrophoresis with ultrasensitive silver staining. All things considered, the best uni-univalent salt was potassium methanesulfonate, while a number of uni-divalent potassium salts of phosphocreatine, hexamethylenediamine N,N,N',N'-tetraacetic acid, sulfate, and succinate were equally acceptable. Using these salts, we determined that changes in Fmax correlated best with variations of ionic strength (1/2 sigma ci z2i, where ci is the concentration of ion i, and zi is its valence) rather than ionic equivalents (1/2 sigma ci magnitude of zi). Our data indicate that increased ionic strength per sc decreases Fmax, probably by destabilizing the cross-bridge structure in addition to increasing electrostatic shielding of actomyosin interactions.

Effect of naloxone on neurohypophyseal peptide responses to breast feeding and breast stimulation in man.

We have investigated the role of endogenous opioid peptides in the release of oxytocin (OT) in response to breast feeding and breast stimulation in humans. Five breast feeding women were studied on two separate occasions within 4 weeks of delivery. Saline or naloxone, 4 mg bolus and 6 mg/h, was administered intravenously, in random order. Blood samples were taken at regular intervals. In the saline-infused group OT rose from a baseline of 1.1 +/- 0.1 pmol/l (mean +/- SEM) to a peak of 7.0 +/- 0.9 after 6 min, and in the naloxone-infused group from 1.0 +/- 0.1 pmol/l to 5.8 +/- 1.3 (P less than 0.05). There were no significant differences between the two groups at any time point. Plasma vasopressin (AVP) did not change. In the second study six women in the luteal phase of the menstrual cycle were investigated on two occasions at least 48 h apart. They were similarly infused with either naloxone or saline in random sequence. A mechanical breast pump provided breast stimulation. In saline-infused women OT levels rose from a baseline of 1.0 +/- 0.1 pmol/l (mean +/- SEM) to a peak of 3.0 +/- 1.1 (P less than 0.05) after 6 min, and in naloxone infused women from 1.1 +/- 0.1 pmol/l to 3.0 +/- 1.4 (NS). There were no differences in OT between the groups. AVP did not change. We conclude that endogenous opioid peptides do not modulate OT release during breast feeding or breast stimulation in women.

Model systems for the evaluation of mucolytic drugs: acetylcysteine and S-carboxymethylcysteine.

The therapeutic place of mucolytic drugs remains uncertain; clinical studies have seldom demonstrated significant benefit and the activity of such agents is poorly understood. In this study the effects of the mucolytic agents acetylcysteine (AC) and S-carboxymethylcysteine (SCMC) have been assessed in-vitro, using purified mucus gels and tracheal explant systems and in-vivo, in the mini-pig tracheal pouch model, in order to elucidate their mechanisms of action. A reduction in the elastic modulus (up to 70% over the frequency range 0.2-20 Hz) was apparent after treatment of mucus gels in-vitro with AC (P less than 0.05), but not with SCMC. Gel chromatography indicated that AC reduced the mucus glycoprotein to smaller subunits and a breakdown of gel structure was apparent when visualized using a cryofracture technique. SCMC treated gels were comparable with control samples. Mucus production was assessed in isolated rat trachea by monitoring the uptake and release of [3H] glucosamine. AC (5-15 mM) did not affect secretion whereas SCMC (5 and 10 mM) reduced the production of radiolabelled material (24 and 37%, respectively) over 24 h (P less than 0.05). Single oral doses of SCMC and AC (20 mg kg-1) were administered to mini-pigs and mucus collected from tracheal pouches; no significant changes in the rheological or biochemical properties of the secretion could be determined. The in-vitro mucolytic activity of AC depends upon a direct action on the secretion, SCMC appears able to reduce production of the mucus glycoprotein. Wide inter- and intra-individual variation in the properties of the secretion would suggest that such effects are not readily demonstrated in-vivo.

Capillary gas-chromatographic analysis of monosaccharides: improvements and comparisons using trifluoroacetylation and trimethylsilylation of sugar O-benzyl- and O-methyl-oximes.

Two new procedures for the gas-chromatographic analysis of monosaccharides are reported. One involves derivatization of the sugars by reaction with O-benzylhydroxylamine followed by trifluoroacetylation with N-methylbis(trifluoroacetamide) and chromatography on a DB-1701 capillary column. This technique probably provides the best resolution achieved to date of the C3-C6 aldoses, as well as of the corresponding alditols. Ketoses can be qualitatively analyzed by this method, but complications interfere with their quantitative analysis. The second procedure also involves initial derivatization as the O-benzyloxime, but is followed by trimethylsilylation with 1-trimethylsilylimidazole, and chromatography on a DB-17 column. This technique is particularly useful for C5 sugars, C6 ketoses, and mixtures of sugars, alditols, and/or lactones. A number of additional, critical, observations on the derivatization and capillary gas-chromatographic analysis of monosaccharides are described.