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Biomedical subjects

S M Schneider

Publications and source records attributed to S M Schneider.

At least 19 recordsLinked to original sources
PubMed1993

Use of sodium polystyrene sulfonate in a lithium overdose.

A 23-year-old woman with an acute-on-chronic lithium overdose received multiple oral doses of sodium polystyrene sulfonate totaling 150 g over a 24-hour period. During the 33 hours after the institution of therapy, the serum lithium level decreased from 4.20 to 0.68 mEq/L. The calculated serum lithium elimination half-life of 12 hours is significantly shorter than that previously noted in other similar overdoses, and the patient suffered no adverse effects of therapy. Multiple-dose sodium polystyrene sulfonate may be useful in lowering the serum lithium level of select patients with acute lithium overdoses but is not a substitute for hemodialysis in severely ill patients.

Acute Disease↗
PubMed1993

Enhanced activated charcoal delivery through small-bore tubing.

Activated charcoal is often given through small-bore tubing for pediatric patients or in attempts to bypass the stomach in patients who are vomiting. The viscosity makes activated charcoal difficult to administer through small-bore tubing. This in vitro study examined several interventions to facilitate flow of aqueous suspension activated charcoal through the small-bore tubing. Aqueous suspension activated charcoal with or without sorbitol had similar flow rates. Precoating the tubing with mineral oil gave only minimal increases in flow rate. A 10% dilution decreased the time to administer 240 ccs of aqueous suspension activated charcoal by 2/3. An additional 10% dilution reduced the time to administer the same dose a further 50%. Minimal dilution of aqueous suspension activated charcoal with tap water greatly increased flow rate through small-bore tubes.

Charcoal↗
PubMed1992

Failure of N-acetylcysteine to reduce alpha amanitin toxicity.

Acetaminophen undergoes toxic conversion in the liver to a free-radical intermediary which binds to glutathione. N-Acetylcysteine acts as a glutathione precursor when natural stores are depleted, and is an effective antidote for acetaminophen overdose. Mushrooms containing amatoxins (such as Amanita phalloides) may undergo similar toxic conversion. However, in our amatoxin-poisoned mouse model, N-acetylcysteine (1.2 g kg-1) produced no change in survival or hepatic enzyme elevation compared to control animals. We conclude that N-acetylcysteine has no clinical role in the treatment of Amanita phalloides ingestion.

Acetylcysteine↗
PubMed1992

Common electrolyte imbalances associated with malignancy.

More than one million Americans will be diagnosed with cancer during 1992, and 50% will be cured of their disease. Of those individuals not cured of the malignancy, survival time after diagnosis has increased tremendously compared to 1980. Because of advances in therapy and the increase in long-term survival, the presence of cancer patients in critical care units should no longer represent either a medical contradiction or an ethical dilemma when the condition requiring critical care is potentially reversible. Many of these individuals may become patients in critical care settings as a result of specific electrolyte imbalances caused by the malignant disease or treatment of malignancy. Although the imbalances often are temporary, they can be life-threatening without intervention. The most common temporary electrolyte imbalances associated with malignant conditions are hypercalcemia, hyperkalemia, and tumor lysis syndrome. Critical care nurses can contribute skill and knowledge in ameliorating these conditions so that the person with cancer can have better quality and longer survival time.

Adult↗
PubMed1992

Orthotopic liver transplants necessitated by acetaminophen-induced hepatotoxicity.

BACKGROUND: Acetaminophen-induced hepatotoxicity has been recognized since 1966. Patients experiencing a massive hepatic insult due to acetaminophen (APAP) may recover with minimal residual complications or develop fulminant hepatic necrosis. We report 3 patients with hepatic failure due to an APAP overdose who received orthotopic liver transplants and survived. CASE REPORTS: An 18-y-o female ingested 60 500 mg APAP tablets (30 g). She presented with tachycardia and lethargy stating that she had taken amoxipine, carbamazepine, and lorazepam. She began to recover but on day 2 experienced an upper gastrointestinal bleed and became hypotensive and hyperpyrexic. She developed hepatic encephalopathy and it was then determined she had ingested APAP. Her APAP level was 13 micrograms/ml 96 h post-ingestion. She was successfully transplanted 19 d post-ingestion with recovery. A 40-y-o female was admitted for flu-like symptoms persisting for 7 d. She was jaundiced, hyperventilating and hypotensive. She admitted ingesting approximately 17 g APAP over 36 h. Her APAP level was 12.2 micrograms/ml. Her condition worsened and on day 3 she was in grade IV coma. She was successfully transplanted 4 d post-arrival with recovery. A 16-y-o female ingested an unknown amount of APAP. She presented approximately 24 h post-ingestion with a serum APAP level of 130 micrograms/ml. Her condition deteriorated and she became encephalopathic with grade IV coma. She was successfully transplanted on day 7 post-arrival. DISCUSSION: Hepatotoxicity can occur as a result of either acute or chronic APAP overdose. Although n-acetylcysteine (NAC) is effective antidotal therapy, it must be used within 8-12 h post-ingestion to be optimally effective. Inaccurate patient histories may prevent NAC administration resulting in hepatotoxicity. CONCLUSION: Liver transplantation is a viable option to be considered in those APAP overdose patients who experience rapidly progressing encephalopathy, hemolysis, and hepato-renal failure.

Acetaminophen↗
PubMed1992

Using diversional activity to enhance coping.

Diversional activity deficit, a nursing diagnosis that occurs with prolonged hospital treatment, requires creative and practical ways for nurses to support patients. A tool designed to assess diversional needs is described. Benefits include improved relationships and enhanced patient coping with a minimum of cost and inconvenience.

Adaptation, Psychological↗
PubMed1991

Effects of alternate routes of epinephrine delivery in experimental bradycardia-hypotension.

The magnitude and rapidity of response to epinephrine given by various routes were evaluated using a new model of bradycardia and hypotension. In ten animals, left ventricular (LV) injection of 10 micrograms/kg of epinephrine was superior to right ventricular (RV) injection in regard to time to attain a 20% increase in heart rate (HR), a 10% increase in mean arterial pressure (MAP) and time to reach peak MAP, although the peak MAP itself did not significantly differ. Similar results occurred with a 15 micrograms/kg dose. Aortic injection in seven of the animals resulted in a much longer time to target HR, an equal time to target MAP and a longer time to peak MAP compared to LV injection. LV injection of epinephrine results in a significantly more rapid onset of action than RV injection in the bradycardic, hypotensive animal. Epinephrine's beneficial effect appears to be derived from its vasoconstrictive, chronotropic and inotropic properties.

Animals↗
PubMed1991

Dextromethorphan poisoning reversed by naloxone.

Dextromethorphan, a common ingredient in cough syrups, has rarely been described to cause toxicity. The authors describe an unusual case of a known asthmatic presenting with somnolence, who appeared to be in end-stage respiratory failure. Her partial response to routine naloxone, 1 mg, was surprising. However, additional naloxone was required to completely normalize the patient's mental status. The authors suggest naloxone be administered in doses of 0.4 mg or more intravenously in suspected dextromethorphan overdose.

Adolescent↗
PubMed1991

Failure of cimetidine to affect phalloidin toxicity.

Phalloidin, a toxin of the mushroom Amanita phalloides, was felt to act as a pro-toxin, converted by hepatic microsomal mixed function oxidase enzymes. Therefore, pretreatment with cimetidine, a potent P450 cytochrome system inhibitor, might be expected to prevent the toxic conversion. In our mouse animal model of phalloidin exposure, pretreatment with 120 mg cimetidine/kg ip failed to improve survival compared to placebo pretreatment. Moreover, cimetidine pretreatment decreased survival (p less than 0.03). These results support an alternate mechanism for phalloidin toxicity, ie, that the toxic effects are related to the interaction of phalloidin with F-actin.

Actins↗
PubMed1990

Association of logistic and Poisson models of infection with some physical characteristics of a single component plant virus.

A logistic model was recently formulated to describe the relationship between concentration of a single component plant virus and infections produced by inoculation to a local lesion host. In this paper the logistic is combined with a Poisson model. The logistic makes accurate fitting possible for a variety of infection-dilution series; and the Poisson acts as a base line, indicating whether lesion numbers are compatible with the hypothesis that random infection of similar infection sites has occurred. A logarithmic form of the logistic equation gives a straight line with negative slope (logit slope) which is useful in characterizing dilution series to which the logistic is fitted. A modified Poisson equation can also be fitted to a range of dilution series; it provides an independent estimate of slope for curves not widely divergent from the standard Poisson. Models have also been developed to define the limits of concentration within which single virions are likely to be randomly dispersed in inoculum without immediate contact with other virions, and are therefore more likely to enter inoculated tissue independently and cause random infections. Models are formulated for aggregation of tobacco mosaic virus in monolayers, crystals, and lenticular aggregates. Published and unpublished data are fitted and analyzed using some of these models.

Models, Statistical↗
PubMed1989

Logistic and Poisson models for infection by multicomponent plant viruses.

A model for the relationship between virus concentration and infectivity of multicomponent plant viruses is based on a combination of logistic and Poisson equations. Two separate equations are derived from the Poisson distribution assuming, (i) that infections occur only when a set of components containing the complete multicomponent genome is established at an infection site, but that any excess of components present does not reduce the probability of infection (no interference postulate); and (ii) that infection can occur only if a set of components containing the full genome reaches an infection site before it can be preempted by an incomplete set (competitive interference postulate). Postulate (i) affects the form of a dilution series without affecting N, the maximum possible number of infections (lesions), and postulate (ii) changes the value of N but not the form of the dilution series. There is a close correlation between the logit slope of a logistic dilution series and the form of the corresponding multiple Poisson dilution series for viruses with 2, 3 or 4 components. Calibrated by Poisson equations, the logit slope may thus suggest whether or not the virus components have invaded independently and infected similar infection sites. The methods of fitting the combined logistic-Poisson model are demonstrated by applying it to data for cowpea chlorotic mottle virus.

Models, Theoretical↗
PubMed1989

Chronic obstructive pulmonary disease.

COPD patients are a heterogeneous group of patients who present with dyspnea and generally follow a progressive downhill course punctuated by acute infections, bronchoconstriction, or respiratory failure. Several drugs are available for relief of symptoms, including beta-agonists, anticholinergics, theophylline, and steroids. Also reviewed are the use of home oxygen and new promising agents.

Adult↗
PubMed1988

High-dose methylprednisolone as initial therapy in patients with acute bronchospasm.

The use of steroids in treating acute respiratory obstruction is still controversial. In this double-blind controlled trial, we decided to examine the beneficial effects of a single large dose of methylprednisolone (MSSP), using objective criteria. In the emergency setting, methylprednisolone (30 mg/kg) has been shown to decrease the need for hospital admission in patients with acute bronchospasm. No difference in this improvement was seen among patients in the steroid-dependent or non-steroid-dependent populations. Based on our findings, we suggest that the early use of single-dose steroid therapy is appropriate treatment for patients with acute bronchospastic attacks.

Acute Disease↗
PubMed1988

The effect of serum potassium on theophylline-induced seizures.

Generalized seizures may be associated with therapeutic or intentional theophylline overdose. Toxic levels of theophylline are also associated with a fall in potassium which could potentiate theophylline-induced seizures. To evaluate the role of serum potassium concentration in theophylline-induced seizures we investigated the seizure threshold in normokalemic and hyperkalemic rats during theophylline infusion to toxic levels. Hyperkalemic rats were prepared with intraperitoneal amiloride and potassium chloride and had a mean +/- SEM initial potassium of 5.29 +/- 0.15 mEq/L. Control animals received either amiloride or potassium and had initial serum potassium concentrations of 4.00 +/- 0.08 and 3.93 +/- 0.16 mEq/L, respectively. Potassium levels after 30 minutes of theophylline infusion were 4.11 +/- 0.18 mEq/L in the hyperkalemic rats and 3.47 +/- 0.06 and 3.51 +/- 0.12 mEq/L in the control animals. There were no significant differences in the serum theophylline concentrations at time of seizure, nor was there a correlation between serum potassium concentration and theophylline concentration at time of seizure. Since the preservation of normokalemia does not influence the onset of seizures in theophylline toxicity, this suggests that the potassium level has little effect on seizure activity in this model.

Animals↗
PubMed1987

Cimetidine protection against alpha-amanitin hepatotoxicity in mice: a potential model for the treatment of Amanita phalloides poisoning.

The ingestion of the mushroom Amanita phalloides is associated with hepatic necrosis appearing clinically two to three days after ingestion. The mechanism of this toxicity is unknown, and no reliable antidote is available. Because of the similarity of Amanita poisoning to other toxins affecting cytochrome P450, we investigated the use of cimetidine (as a P450 cytochrome inhibitor) as an antidote against a primary toxin of the mushroom alpha-amanitin. Mice injected with alpha-amanitin and given cimetidine either prophylactically or within six hours showed histologic protection from the hepatic damage seen in control mice. Control animals displayed significant mitochondrial changes when examined by electron-microscopy, while the mitochondria of the cimetidine-treated animals were preserved, suggesting a possible site for toxin action. Further trials will be necessary before treatment of human cases with cimetidine is indicated.

Amanita↗