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Biomedical subjects

J A Feldman

Publications and source records attributed to J A Feldman.

27 records · Page 2Linked to original sources
PubMed1977

High-performance liquid chromatographic radioenzymatic assay for plasma catecholamines.

A new assay method for plasma CA's requiring only 50 microliter has been developed, which uses HPLC. The NE, D, and E compounds found in plasma are radioactively o-methylated with 3H-SAM by the reaction of COMT. The reaction is terminated and a standard mixture of nonradioactive o-methylated analogues of NE, D, and E is addded to act as a carrier. Following separation by HPLC, the NMN, 3-MOT, and MN radioactive peaks are collected which represent NE, D, and E, respectively. Then MNM and MN are oxidized to vanillin, and 3-MOT is acetylated. The products are subsequently separated by solvent extraction. This is necessary in order to avoid high radioactive blanks and to allow quantitation of the radioactivity by liquid scintillation spectrometry. The mean supine levels of NE, D, and E in normal subjects were respectively 182, 33, and 87 pg/ml of plasma. Similar assays on patients with pheochromocytoma revealed 797, 80, and 470 pg/ml.

Adult↗
PubMedDate not supplied

Resuscitation fluid for a patient with head injury and hypovolemic shock.

The resuscitation of a patient with severe closed head injury and hypovolemic shock is a commonly encountered clinical scenario. The optimal resuscitation formula remains controversial. Aggressive use of crystalloid solutions may worsen brain injury. Early use of mannitol or hypertonic agents may worsen hemorrhage and shock. The optimal approach to the resuscitation of a patient with head trauma and hypovolemic shock is reviewed and discussed. Recent experimental evidence suggests that the early inclusion of an agent such as mannitol in the resuscitation formula may be appropriate despite the evidence of shock. However, the controversy remains unresolved.

Animals↗
PubMedDate not supplied

Interference of herbal drinks with urinalysis for drugs of abuse.

Recently there have been claims among drug users that some herbal drinks interfere with urinalysis for drugs of abuse and yield false positive results. Proof of such claims has yet to be shown. Screening for drugs of abuse is usually carried out using fluorescence polarization immunoassay (FPIA) or thin-layer chromatography (TLC). Fifty herbal samples which are considered among the most purchased herbs in the consumer market were used to investigate such claims. The drug groups that were tested for included amphetamines, opiates, barbiturates, cocaine metabolite, methadone, and their analogs. The herbs were analyzed at different concentrations (0.1, 1, 3, and 5 g/100 mL of distilled water) using TLC and FPIA to determine if any interfere with urinalysis for drugs of abuse and yield false positive results. For the FPIA test, the sample infusions were analyzed directly using the automated ADX analyzer (Abbott Laboratory). For TLC, infusions of the herbs were added to a solid-phase extraction column (pH 9.25), then extracted with a methylene chloride-isopropanol solvent system. At this pH, neutral, basic, and acidic drugs of abuse are extractable. The developed chromatographic plates were sprayed sequentially with several reagents. None of the herbs in the concentration ranges screened showed any interference with TLC or FPIA, indicating the invalidity of such claims.

Beverages↗
PubMedDate not supplied

Prospective multicenter evaluation of cocaine-associated chest pain. Cocaine Associated Chest Pain (COCHPA) Study Group.

OBJECTIVE: To describe a large cohort of patients who had chest pain following cocaine use, and to determine the incidence of and clinical characteristics predictive for myocardial infarction in this group of patients. METHODS: A prospective observational cohort study of consecutive patients with cocaine-associated chest pain was conducted in six municipal hospital emergency departments (EDs). Demographic variables, drug abuse patterns, medical histories, chest pain characteristics, ECG results, and laboratory data were recorded. Myocardial infarction was the primary endpoint. RESULTS: Fourteen of 246 patients (5.7%; 95% confidence interval [CI], 2.7-8.7%) had myocardial infarction, as diagnosed by elevated CK-MB isoenzyme levels. There were two deaths (0.8%). The patients had a median age of 33 years. The majority were male (71.5%), non-white (83.3%), cigarette smokers (83.3%) who used cocaine regularly. Chest pain began a median of 60 minutes after cocaine use and persisted for a median of 120 minutes. Chest pain was most frequently described as substernal (71.3%) and pressure-like (46.7%). Shortness of breath (59.3%) and diaphoresis (38.6%) were common. There was no clinical difference between patients who had myocardial infarctions and those who did not. Twelve patients had arrhythmias and four had congestive heart failure. All cases requiring intervention were evident upon presentation. An ECG revealing ischemia or infarction had a sensitivity of 35.7% for predicting a myocardial infarction. The specificity, positive predictive value, and negative predictive value of the ECGs were 89.9%, 17.9%, and 95.8%, respectively. CONCLUSIONS: Myocardial infarction in patients who have cocaine-associated chest pain is not uncommon. No clinical parameter available to the physician can adequately identify patients at very low risk for myocardial infarction. Therefore, all patients with cocaine-associated chest pain should be evaluated for myocardial infarction.

Adult↗