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Biomedical subjects

S K Gordon

Publications and source records attributed to S K Gordon.

At least 19 recordsLinked to original sources
PubMed1994

Prevalence of deep venous thrombosis in patients with chronic spinal cord injury.

From a group of 229 patients with chronic spinal cord injury (SCI) who were admitted to an SCI Service of a Veterans Affairs Medical Center, a prospective study was performed to determine the prevalence of deep venous thrombosis (DVT) using radionuclide venography on 43 patients in whom this diagnosis was entertained by clinical examination. By physical examination of the total population of 229 patients on admission, patients were selected and then divided into two groups: the clinically DVT-free group (22 patients) and the clinically DVT-suspected group (21 patients). In the clinically DVT-free group, two cases of chronic DVT (9.1%) were detected incidentally. In the clinically DVT-suspected group, 2 cases of chronic DVT (9.5%) and 4 cases of acute DVT (19.0%) were found. In one subject in the DVT-free group, a false positive radionuclide study was suspected and proven by contrast venography. In the 43 patients studied by radionuclide venography, the prevalence of acute DVTs was 9.3% and chronic DVTs, 9.3% (7.0% "true" chronic DVTs). No subjects in the clinically DVT-free group had an acute DVT. Five of 8 DVTs (62.5%) were detected greater than 6 years after SCI and 3 of 4 (75%) of the acute DVTs developed 17 to 33 years after SCI. Thus, the prevalence of acute DVT cases in this chronically immobilized cohort was found to be relatively low when compared with that in prior reports in those with acute SCI, but the prevalence rate of acute DVT cases in the study herein is similar to or lower than that found in the surgical or medical nonambulatory, non-SCI population.

Acute Disease↗
PubMed1992

Depressed serum high density lipoprotein cholesterol levels in veterans with spinal cord injury.

Cardiovascular diseases are the most frequent cause of death among persons with spinal cord injury (SCI), and these diseases are reported to occur prematurely in the disabled compared to the able bodied population. The mechanism of accelerated coronary heart disease (CHD) in persons with SCI may be partially explicable on the basis of the lipoprotein profile. We performed fasting lipoprotein determinations on 100 veterans with SCI, 50 with paraplegia and 50 with quadriplegia, and 50 veteran controls. The mean age of the subjects with SCI was 47.8 +/- 1.4 years with a duration of injury of 16.3 +/- 1.2 years. The mean serum high-density lipoprotein (HDL) cholesterol was depressed in subjects with paraplegia or quadriplegia compared to controls (37 +/- 1 or 40 +/- 1 versus 48 +/- 2 mg/dL, p < 0.0001). Although serum total cholesterol was lower (p < 0.01) in subjects with SCI than in controls, there was no significant difference in mean serum low-density lipoprotein (LDL) cholesterol. Thirty-seven percent of subjects with SCI have serum HDL cholesterol levels less than 35 mg/dL with no significant difference in lipoprotein distribution between high and low cord lesions. Eighteen percent of individuals with SCI have an absolute elevation of LDL cholesterol (greater than 160 mg/dL). About 40% of those with SCI and LDL cholesterol levels between 130 and 160 mg/dL also have serum HDL cholesterol values below 35 mg/dL, all of whom would have their serum HDL cholesterol level undetected if lipoprotein profiles were performed according to present recommendations--that is, only if the serum total cholesterol is elevated.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Drug use and abuse in an urban veteran spinal cord injured population.

Substance abuse in the spinal cord injured (SCI) population has been addressed in a few controlled studies. These reports have led to the belief that many SCI patients were illicit drug users prior to their injury and that their drug abuse was a contributing cause of their accidents. One large study determined from answers obtained on a questionnaire that drug abuse, other than alcohol, was prevalent among injured veterans. Our study uses urine toxicology to determine the frequency of drug use and abuse, excluding alcohol, in 72 inpatients and 81 outpatients associated with an urban Veterans Affairs Medical Center. In a blinded experiment, urinary concentrations of opiates, barbiturates, amphetamines, methadone, benzodiazepines, and cocaine were determined with Syva reagents on an Abbott VP. Urinary cannabinoids were determined using Abbott TDX and the FPIA method. The use of illicit (unprescribed) drugs was surprisingly low (< or = 13 percent) for an urban medical center. Outpatient cannabinoid abuse was significantly more frequent than inpatient usage (p < 0.01). Barbiturates were not found in any patient. Benzodiazepines were taken most commonly (29 percent). Since benzodiazepine usage is the direct result of physician prescription, wide-spread usage of this agent is avoidable. Physicians should pay attention to the probable deleterious consequences of benzodiazepine addiction related to depressive effects on the central nervous system caused by its chronic use.

Adult↗
PubMed1992

Gastrointestinal transit after spinal cord injury: effect of cisapride.

Heartburn, bloating, and abdominal discomfort are common problems in patients with spinal cord injury but, despite its clinical significance, little is known about the gastrointestinal effects of spinal transections. To address the potential gastrointestinal pathophysiology of spinal cord injury, we measured mouth-to-cecum transit time (MCTT) in seven subjects with paraplegia and seven with quadriplegia. Gastric emptying was studied in six subjects with quadriplegia. MCTT was significantly prolonged in patients with quadriplegia, an abnormality corrected by the administration of cisapride. Patients with paraplegia, in contrast to those with quadriplegia, have normal mouth-to-cecum transit time. In addition, patients with quadriplegia had neither a prolonged gastric emptying time nor a change in gastric emptying time, with cisapride. Changes in gastrointestinal transit after spinal cord injury and the improvement of mouth-to-cecum transit time in subjects with quadriplegia, but not in those with paraplegia, may be explained by an imbalance between parasympathetic and sympathetic outflows to the gastrointestinal tract in this group of subjects.

Adult↗
PubMed1988

Amikacin pharmacokinetics in patients with spinal cord injury.

The influence of chronic (greater than 1 yr duration) spinal cord injury (SCI) on the disposition of amikacin was studied in seven healthy subjects with SCI (five paraplegic, two tetraplegic) and seven able-bodied controls (intact neuraxes). The time course of amikacin serum concentration after a 30-minute infusion (7.5 mg/kg) was followed for up to 8.5 hours using fluorescence polarization immunoassay. Pharmacokinetic values were estimated by a noncompartmental analysis (NC). Amikacin steady-state volume of distribution (Vss) was increased to 0.20 +/- 0.04 l/kg (mean +/- SD) as compared to 0.17 +/- 0.02 l/kg in able-bodied controls (p 0.03), and its mean terminal elimination half-life in patients with SCI was prolonged by 0.64 hours over the control value of 2.11 +/- 0.27 hours (p 0.01). The NC estimated mean residence time (MRT) in patients with SCI (3.65 +/- 0.75 hrs) was 0.89 hours longer than that observed in controls (p 0.03). Our data suggest that the Vss, half-life, and MRT of amikacin are increased in persons with chronic SCI. As a result, amikacin dosing regimens developed in able-bodied humans may demonstrate diminished efficacy when extrapolated uncritically to these patients.

Adult↗
PubMed1988

Non-traumatic ischaemic myelopathy: a review of 25 cases.

The causes of ischaemic myelopathy are described in 25 patients. Nine developed following surgical manipulation or traumatic laceration of the aorta, 1 following intercostal artery ligation, 3 following aortic aneurysm dissection, 2 following myocardial infarction and/or cardiac arrest, 7 in the absence of any specifically identifiable predisposing factors, and 3 in association with decompression sickness. The degree of clinical recovery was greater among those with incomplete spastic (as opposed to complete flaccid) paralysis and among those in whom sensory loss below the level of injury was incomplete. Despite the diversity of mechanisms that may lead to the development of spinal cord ischaemia, structural damage seems in most instances to affect either grey matter or white matter predominantly. Some of the possible reasons for these preferential sites of damage are discussed.

Aorta↗
PubMed1987

Ah receptor in human placenta: stabilization by molybdate and characterization of binding of 2,3,7,8-tetrachlorodibenzo-p-dioxin, 3-methylcholanthrene, and benzo(a)pyrene.

Aryl hydrocarbon hydroxylase (AHH, cytochrome P1-450) is highly inducible in several human cells and tissues exposed to specific halogenated and nonhalogenated aromatic chemicals of the "3-methylcholanthrene-type." In laboratory animals AHH induction is known to be regulated by binding of inducers to the Ah receptor, a soluble intracellular protein. However, the induction mechanism in the human species is incompletely understood largely because the Ah receptor, which seems to be essential to the induction process, has not previously been detectable in certain human cells and tissues (including placenta) that are highly responsive to AHH induction. We found that human placenta contains high concentrations of Ah receptor (comparable to the receptor concentrations in rat and mouse liver) but that special modifications were necessary in the assay techniques in order to detect and accurately quantitate receptor binding. Receptor was detected at concentrations approximately equal to 100 fmol/mg cytosol protein using [3H]2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) as the radioligand. This high concentration of specific binding sites was present only if the placental tissue was initially homogenized in a buffer containing sodium molybdate (10 or 20 mM). Without molybdate in the homogenizing buffer, specific [3H]TCDD binding was only about 35 fmol/mg. Specific Ah receptor binding also was detectable with [3H]-3-methylcholanthrene and, to a lesser extent, with [3H]-benzo(alpha)pyrene. The receptor sedimented near 9S on sucrose gradients whether molybdate was present or not. About 80% of specific binding was lost if excessive charcoal was used to adsorb "nonspecifically bound" ligand from cytosol prior to gradient analyses. The apparent affinity with which [3H]TCDD bound to Ah receptor in human placental cytosol was relatively low (apparent Kd approximately equal to 5 to 8 nM) when compared with the affinity of [3H]TCDD binding in rat or mouse hepatic cytosols (Kd approximately equal to 1 to 3 nM). These data suggest that while molybdate has very little effect on the quantity or molecular size of the rodent Ah receptor assay, it is very important in stabilizing the human Ah receptor. Our experiments demonstrate that human placenta contains a high concentration of Ah receptor and suggest that AHH induction in placenta is mediated through a receptor mechanism analogous to that previously established in tissues and cells from laboratory animals.

Benzo(a)pyrene↗
PubMed1987

Theophylline disposition in tetraplegic man.

We studied the time-course of serum theophylline concentration after a 30-minute intravenous infusion of aminophylline (6 mg/kg) in 18 traumatic tetraplegic (nine smoking, nine nonsmoking) and in six control (nonsmoking) subjects. All study subjects were healthy men with normal renal function. Pharmacokinetic parameters were calculated from a linear regression analysis of the terminal log-linear portion of the log serum theophylline concentration-time curves. The terminal elimination kinetics of theophylline in this study were best characterized by first order elimination from a one compartment-open model. A statistically significant difference (P less than .05) was demonstrated between the means and variances of theophylline clearance (Cl ml/kg/min) and hours of half-life (t1/2) for control subjects and smoking tetraplegics. Total body clearance of theophylline was greater in all tetraplegic subjects, the greatest difference in total clearance of theophylline adjusted to body weight being observed between tetraplegic smokers and nonsmoking controls with an intact central nervous system (P less than .05). Theophylline volume of distribution (Vdarea) did not differ significantly from Vdarea in able-bodied subjects. Tetraplegic individuals have multiple disorders and marked pharmacokinetic variation, which might be expected to make serum concentration and toxicity of theophylline unpredictable using population averages.

Adult↗
PubMed1985

Gentamicin disposition kinetics in humans with spinal cord injury.

The disposition kinetics of gentamicin, an aminoglycoside antibiotic, were studied in seven tetraplegic and six paraplegic volunteers. The volume of distribution of gentamicin in l/kg of body weight varied in a statistically significant way from values of this parameter measured in normal subjects. The elimination of gentamicin in spinal man proceeded in a log-linear fashion accurately characterized by a one compartment open-model with a half-life of approximately 2 hours. The clinical significance of altered disposition kinetics and an increased intersubject variability in gentamicin disposition in spinal man as compared to normal subjects is unknown. The existence of these observed differences in pharmacokinetic parameters, however, emphasizes the need to define individual pharmacokinetic profiles and individualize dosing regimens in spinal man. The data presented are supportive of the hypothesis that spinal man constitutes a discreet therapeutic population.

Adult↗
PubMed1975

Organization and recall of related sentences by elderly and young adults.

Differences between elderly and young adults in storage organization of sentence material were investigated using a modification of Mandler's (1967) sorting technique. The elderly were expected to be relatively poor at sorting organization, and would then recall less sentence material. The age groups were also compared on time taken to organize the sentences, recall organization, and performance on a short sentence comprehension test. There were no age differences in conceptual type of organization or clustering of sentences in sorting groups and recall storage organization was not related to the amount of recall. The elderly adults did require more time to acquire the sentences, and had lower recognition test scores. It was concluded that the sorting technique and measures related to it failed to detect the elderly adults' apparent difficulty in acquiring the sentences.

Adult↗