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Biomedical subjects

M D Robinson

Publications and source records attributed to M D Robinson.

34 records · Page 2Linked to original sources
PubMed1986

Painless dissection of the thoracic aorta.

A 64-year-old man presented to an emergency department with a two-week history of intermittent, bilateral lower extremity paralysis without associated chest, abdominal, or back pain. He subsequently deteriorated and died as a result of a thoracic aortic dissection. This unusual case is reported, and the pathophysiology, diagnosis, and management of aortic dissection are discussed.

Aortic Dissection↗
PubMed1986

Hydrogen sulfide poisoning from toxic inhalations of roofing asphalt fumes.

Hydrogen sulfide poisoning from inhalation of roofing asphalt fumes is a rare but devastating injury. Two cases of toxic inhalation involving exposure to several gases, including hydrogen sulfide, evolved from cooling asphalt, are presented. Both victims were treated with supportive measures, including 100% normobaric oxygen, and one also received sodium nitrite. In one patient rapid, complete recovery was temporally associated with nitrite administration. The patient not treated with sodium nitrite survived with apparently permanent severe neurological sequelae.

Adult↗
PubMed1986

Late death in tricyclic antidepressant overdose revisited.

We report a late death following the ingestion of amitriptyline. A 46-year-old woman presented to the emergency department with coma, hypotension, tachycardia, and a prolonged QRS interval after the ingestion of a large quantity of Elavil. She was managed with aggressive supportive care, multiple doses of oral charcoal, and charcoal hemoperfusion. The patient's ECG and hemodynamic status returned to normal within 24 hours. Despite an apparent total recovery, she suddenly sustained a cardiorespiratory arrest and died 33 hours after ECG normalization (at 57 hours after admission). This case brings into question the feasibility of ceasing ECG monitoring in tricyclic antidepressant overdoses once the ECG has stabilized, especially in patients with a history of chronic usage. A possible explanation for late sequelae is the myocardial cell binding and depressant effect of preexisting therapeutic TCA medication.

Amitriptyline↗
PubMed1985

Deoxygenated sickle hemoglobin. Modulation of its solubility by 2,3-diphosphoglycerate and other allosteric polyanions.

The effects of 2,3-diphosphoglycerate (DPG) and other allosteric polyanions of the phosphate or sulfate ester class (inositol hexaphosphate (IHP), ATP, pyridoxamine-5'-phosphate (PMP), and inositol hexasulfate (IHS] on the solubility of deoxyhemoglobin S, and the oxygen affinity of Hb A were evaluated. Their effects on the saturation concentration (csat) indicated promotion of gelation in each case, according to the following order of molar effectiveness: IHP greater than IHS greater than DPG greater than ATP much greater than PMP. Four polybasic carboxylic acids (benzenetricarboxylate (trimesic acid), benzenetetracarboxylate (BTC), benzenepentacarboxylate (BPC), and benzenehexacarboxylate (BHC] were evaluated as well. Their order of molar effectiveness was: BHC greater than BPC greater than BTC much greater than trimesic acid. Both classes of polyanions influenced oxygen affinity in the same order as solubility. Overall, a good correlation existed between the negative charges of these nine allosteric polyanions at neutral pH and their effects on solubility and oxygen affinity. Because of its possible role in the pathophysiology of sickle cell disease, the effect of DPG on csat was examined over the pH range 6.5-7.6. While a decrease in csat was observed for DPG-saturated deoxyhemoglobin S throughout this range, the decrement observed in the physiological pH range (1.8 g/dl) was somewhat lower than that below neutral pH (3.0 g/dl); in either case the sickling tendency of SS red cells would be enhanced. Inasmuch as the intracellular concentration of DPG in sickle cell anemia may be elevated as much as 2-fold, maneuvers aimed at its reduction could be therapeutically beneficial.

2,3-Diphosphoglycerate↗
PubMed1985

Traumatic tension pneumopericardium: a case report and literature review.

A 39-year-old male arrived in the emergency department with multiple stab wounds to the chest. A pneumopericardium was present on initial chest x-ray study. He subsequently developed hypotension, tachycardia, an elevated CVP (36 cm H2O) and a pulsus paradoxus. All parameters improved following removal of 100 cc of air by pericardiocentesis. The etiology, diagnosis, pathophysiology, and treatment of tension pneumopericardium are discussed.

Adult↗
PubMedDate not supplied

Ritalin for nicotine withdrawal: Nesbitt's paradox revisited.

This was a unblinded clinical trial of the stimulant methylphenidate (Ritalin) for nicotine withdrawal. Nineteen nicotine-dependent smokers received oral methylphenidate (30 mg target daily dosage) for 5 days following abrupt cessation. Tobacco withdrawal, Spielberger state anxiety, blood pressure, and pulse were measured at baseline, then serially for 7 days. Tobacco withdrawal and state anxiety increased significantly, but 12 (71%) of the 17 smokers who completed the study rated withdrawal relief "very define" and 13 (76%) rated this quit attempt "much easier than other times." Methylphenidate neither increased blood pressure nor blocked cessation-related pulse decrease and appears safe for this indication. Twelve (63%) of the enrolled smokers were confirmed abstinent at day 5. Methylphenidate effect on nicotine withdrawal should be studied in a placebo-controlled clinical trial.

Administration, Oral↗
PubMedDate not supplied

Comparison of enzyme mismatch cleavage and chemical cleavage of mismatch on a defined set of heteroduplexes.

Two mutation detection methods based on the cleavage of mismatched heteroduplexes were compared and evaluated. These techniques, chemical cleavage of mismatch (CCM) and enzyme mismatch cleavage (EMC), have the advantages over other available methods of being able to detect and localize mutations in relatively large fragments of DNA (> or = 1 kb). We have constructed clones that enable us to create heteroduplexes of 500 bp, 1 kb, and 1.5 kb and have assessed each of the methods over a range of criteria. Both were able to detect and localize all four types of single-base mismatch and insertion/deletions of 1-5 bp. Whereas EMC was efficient at detection of insertion/deletions in a broad size range of fragments and has the advantage over CCM of using no hazardous chemicals, in our hands it has not been sufficiently robust that we felt confident to consider it for diagnostic use in its present form. CCM using hydroxylamine was efficient over the entire range of fragment sizes tested and using potassium permanganate with tetraethylammonium chloride was efficient up to 1 kb.

Base Pairing↗
PubMedDate not supplied

Changes in cardiac excitability and vulnerability in NMR fields.

Alterations in ventricular excitability and vulnerability were assessed in nine isolated perfused rabbit hearts in and out of static external magnetic fields (4.7 tesla) associated with radiofrequency pulsing (5 gauss). Ventricular refractoriness was assessed with the strength interval relationship in and out of the NMR magnet. Strength interval curves were measured at threshold, at the midpoint of the strength interval relationship, and at 10 mA. The refractory period measured at threshold was 193 +/- 24 mS outside the magnet and 195 +/- 24 mS inside the magnet (P = ns). Ventricular refractoriness measured at the midpoint of the strength interval curve was 169 +/- 16 mS outside and 167 +/- 17 mS in the magnet (P = ns). At 10 mA the refractory period outside of the magnet was 162 +/- 16 mS and 161 +/- 17 mS in the magnet (P = ns). To assess ventricular vulnerability the repetitive response threshold and the ventricular fibrillation threshold were also determined in and out of the NMR magnet. The repetitive response threshold was 61 +/- 16 mA out of the magnet and 75 +/- 24 mA inside the magnet. This was significant at the P = 0.04 level. The ventricular fibrillation threshold was 71 +/- 14 mA out of the magnet and 81 +/- 20 mA in the magnet (P = ns). In summary, static magnetic fields associated with radiofrequency pulsing have no measureable effect on the strength interval relationship. There is no increase in ventricular vulnerability as assessed by the repetitive response threshold and the ventricular fibrillation threshold.

Animals↗
PubMedDate not supplied

Buspirone effect on tobacco withdrawal symptoms: a randomized placebo-controlled trial.

BACKGROUND: Withdrawal symptoms hinder smoking cessation in nicotine-dependent smokers. This prospective, double-blind, placebo-controlled clinical trial was conducted to evaluate buspirone for nicotine withdrawal symptoms. METHODS: Fifty-four heavy smokers (mean 33.1 cigarettes per day for 24 years) were randomly prescribed 30 mg/d of buspirone or placebo beginning 3 weeks before abrupt smoking cessation. Validated nicotine withdrawal and anxiety scales were administered at baseline and serially for 2 weeks after cessation. RESULTS: Baseline demographic and nicotine-dependence measures were similar for each group. Three smokers (1 on buspirone, 2 on placebo) dropped out of the protocol prior to the quit date. Both groups had significant withdrawal effects over time (analysis of variance [ANOVA] P = 0.0001). There was a significant buspirone effect on any nicotine withdrawal symptoms (ANOVA, alpha = 0.05). Smokers who relapsed, regardless of group, reported significantly worse craving, irritability, anxiety, and difficulty concentrating than abstainers (P less than 0.05). Relapse rates at follow-up visits were not significantly different between groups. Two-week abstinence rates were 52 percent for placebo and 62 percent for buspirone (chi-square, P = 0.760). CONCLUSIONS: In these heavy smokers, buspirone offered no relief from nicotine withdrawal symptoms. Regardless of treatment, relapsing smokers experienced more intense nicotine withdrawal.

Adolescent↗
PubMedDate not supplied

Buspirone effect on tobacco withdrawal symptoms: a pilot study.

Tobacco withdrawal symptoms hamper smoking cessation. This was a pilot study of buspirone, a new azapirone anxiolytic, for tobacco withdrawal. Thirteen smokers entered an open clinical trial. Smokers were titrated to 30 mg/day of oral buspirone for 2 weeks prior to cessation. Tobacco withdrawal and Spielberger state-anxiety scales were used at baseline, on the quit date, and then at 24 hours, 48 hours, 1 week, and 2 weeks after abrupt cessation. At the final visit, smokers compared their withdrawal experience with previous cessation attempts. Two patients (15 percent) could not tolerate the medication and did not attempt smoking cessation. Of the remaining 11 smokers, 3 (27 percent) rated withdrawal relief "very definite," 6 (55 percent) "moderate," and 2 (18 percent) "slight." More than two-thirds of the smokers believed that their difficulty concentrating, craving, restlessness, and anxiety were improved compared with earlier tobacco withdrawal attempts. Five patients (46 percent) reported decreased smoking urges during the 2-week medication titration period. Tobacco withdrawal symptoms and state-anxiety scores changed significantly during the study (P less than 0.05). These results are encouraging, but they should be interpreted with caution because of the small sample size and lack of placebo control. Buspirone effect on tobacco withdrawal symptoms should be studied in a randomized, controlled clinical trial.

Adult↗
PubMedDate not supplied

Impact of compliance and side effects on the clinical outcome of patients treated with oral erythromycin.

STUDY OBJECTIVE: To determine the relationship among compliance, side effects, and self-reported outcome for patients in an erythromycin trial. DESIGN: A retrospective analysis of data from a multicenter, prospective, single-blind, randomized trial. SETTING: Five metropolitan ambulatory care offices. PATIENTS: The 252 adults (> 18 yrs) were prescribed oral erythromycin 1.0 g/day (base equivalent) for infectious disorders. INTERVENTION: Subjects received erythromycin for 10 days and reported compliance, drug efficacy, and side effects in a daily diary. Compliance was measured by tablet count. RESULTS: A negative correlation was found between gastrointestinal symptom severity score and percentage of tablets taken (p < 0.001). A significant positive correlation was seen between compliance and outcome (p < 0.001). Subjects who took greater than 80% of the drug achieved the treatment goal more frequently than those taking 80% or less (94% vs 59%, p < 0.001). CONCLUSIONS: Side effects of erythromycin adversely affected compliance. Compliance had a positive effect on self-reported outcome.

Administration, Oral↗