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Biomedical subjects

J Cameron

Publications and source records attributed to J Cameron.

At least 109 records · Page 6Linked to original sources
PubMed1987

The etiologic spectrum of constrictive pericarditis.

Ninety-five consecutive patients with constrictive pericarditis that was documented at the time of surgery during 1970 to 1985 were reviewed. The etiologies included idiopathic (42%), postradiotherapy (31%), post-cardiac surgery (11%), postinfective (6%), connective tissue disease-related (4%), neoplastic (3%) uremic (2%), and sarcoidosis (1%). Post-cardiac surgery etiology was seen only after 1980, but constituted 29% of cases during 1980-1985. Postradiotherapy etiology occurred with equal incidence in 1980-1985 and in 1970-1980, but the interval from radiotherapy to presentation with constrictive pericarditis was longer in the more recent period (11 vs 4.75 years). Effusive constrictive pericarditis occurred in 24% overall with similar prevalence in all of the etiologic groups except the postsurgical cases, which were caused by noneffusive fibrous constrictive pericarditis in all instances. Operative mortality was 12% overall: It was lower in the idiopathic group (8%) and higher in the postradiotherapy group (21%). Thus postradiotherapy constrictive pericarditis continues to occur despite technical changes aimed at reducing its likelihood, but recent cases have a longer latent period: and postsurgical constrictive pericarditis has emerged as an important etiology.

Adult↗
PubMed1987

The use of mechanical stimulation to obtain the sacral reflex latency: a new technique.

We determined sacral reflex latencies and morphologies in 18 neurologically normal patients and 83 with neurological disease by stimulating the glans penis or clitoris using electrical and a new technique of mechanical stimulation, and recording from the external urethral sphincter. The results with both stimulation techniques were compared among various diagnostic groups. In normal patients the mean sacral reflex latencies were 35.3 +/- 2.5 (standard deviation) msec. with electrical stimulation, and 39.1 +/- 4.0 msec. with mechanical stimulation. The mean reflex latencies in patients with lower motor neuron lesions studied by both methods were statistically longer than in normal subjects, and the mean reflex latencies in patients with upper motor neuron impairment studied by both methods were not statistically different from those in normal subjects. The morphological findings of the reflex tracings suggest that both types of evoked responses follow the same general anatomical pathway and both resemble a special human flexor reflex. The mechanical technique has advantages over the electrical technique because it is less painful and in certain instances it is easier to obtain.

Adult↗
PubMed1985

Hypereosinophilic heart disease.

A 45-year-old patient with cardiac involvement from the idiopathic hypereosinophilic syndrome suffered from severe congestive cardiac failure with progressive deterioration despite intensive medical therapy. Investigations indicated bilateral ventricular infiltration with endomyocardial fibrosis which had caused severe haemodynamic restriction and bilateral atrioventricular valvular incompetence. Extensive surgery, which included bilateral ventricular endomyomectomy and mitral and tricuspid valve replacements, resulted in a significant improvement for six months.

Endomyocardial Fibrosis↗
PubMed1985

Right heart thrombus: recognition, diagnosis and management.

The clinical, echocardiographic, hemodynamic, angiographic and pathologic features of five patients who had right heart thrombus are presented and their management is discussed. Two modes of presentation were recognized. In four patients, right heart thrombus complicated peripheral venous thrombosis and was associated with major pulmonary thromboembolism and right heart obstruction. In the fifth, it complicated myocarditis with heart failure and appeared to cause right heart obstruction. Two-dimensional echocardiography was diagnostic of right heart thrombus in four patients and showed evidence of right heart dysfunction in those with major pulmonary thromboembolism. The diagnosis was confirmed at surgery in three patients and at autopsy in one. Three patients successfully underwent surgical removal of the thrombus followed by anticoagulation. One patient was treated successfully with anticoagulation alone. The only death occurred in the patient with myocarditis.

Adolescent↗
PubMed1985

Pre-pubertal gynaecomastia as the presenting feature of late-onset 21-hydroxylase deficiency.

We describe an 8-year-old boy with pre-pubertal gynaecomastia as the presenting feature of late-onset 21-hydroxylase deficiency, an association not previously reported. Although absolute oestrogen levels were not higher than previously described in 21-hydroxylase deficiency, the gynaecomastia may have arisen through a relative disproportion of the C18 to C19 steroids.

Adrenocorticotropic Hormone↗
PubMed1985

Differences in norepinephrine activation and diltiazem inhibition of calcium channels in isolated rabbit aorta and mesenteric resistance vessels.

The mechanisms of norepinephrine stimulation of calcium ion entry in isolated rabbit aorta and mesenteric resistance vessels were studied through measurements of effects on calcium-45 influx, tension, and membrane potential. The resistance vessels were considerably less sensitive to norepinephrine than the aorta. The aorta exhibited complex dose-response curves for norepinephrine-stimulated calcium influx and contraction, whereas these were simple in the arterioles. Both vessels were depolarized with increasing concentrations of potassium. Norepinephrine did not depolarize the aorta, whereas it did depolarize the mesenteric resistance vessels. This result supports the contention that norepinephrine opens receptor-operated channels to induce calcium entry in the aorta, while it may activate potential sensitive calcium channels in the mesenteric resistance vessels. However, the maximum depolarization with norepinephrine (10(-4) M) in the arterioles was completely blocked by 10(-5) M diltiazem, whereas that induced by 80 mM potassium was unaltered by the diltiazem. Furthermore, 10(-4) M norepinephrine was able to stimulate virtually the same contraction and calcium influx in 80 mM potassium-depolarized arterioles as in normal polarized tissues. These results are consistent with norepinephrine opening of receptor-operated channels to allow calcium entry in the rabbit mesenteric resistance vessels. That the behavior of norepinephrine-activated channels in the aorta is more complex than in the arterioles is further illustrated by a dramatically decreasing sensitivity of norepinephrine-stimulated calcium influx to diltiazem with increasing norepinephrine in the aorta but not in the arterioles.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Cloning of Bordetella pertussis outer membrane proteins in Escherichia coli.

We have cloned in Escherichia coli a 40 kb chromosomal DNA fragment of Bordetella pertussis which encoded the synthesis of two major outer membrane proteins specific to this microorganism. The clone harbouring the plasmid pFSH200 has shown modulation of the expression of these proteins when grown on complete solid medium. However, this phenomenon has not occurred in clones harbouring smaller derivatives of plasmid pFSH200 and one such derivative, plasmid pFSH201, has been isolated and further characterized. These results suggest that the large plasmid pFSH200 contained a regulatory sequence affecting the expression of the outer membrane proteins of Bordetella pertussis in Escherichia coli. This sequence is very likely responsible for the antigenic modulation observed in phase I strains of Bordetella pertussis.

Antigens, Bacterial↗
PubMed1985

Cinemicroscopic studies of lymphocyte behavior in semi-solid medium: the polyclonal origin of lymphocyte colonies.

Time-lapse cinemicroscopy was used to observe the development of lymphocyte colonies in a phytohemagglutinin-dependent one-step, two-layer agar culture system. More than 1000 h of culture time were recorded in a total of 14 independent experiments. Blast formation and organization of lymphocytes into highly motile pairs and clusters occurred early in culture (0-3 days). An increase in thymidine uptake also preceded the first detectable proliferation by 24 h. Mature lymphocyte colonies were found to be dynamic entities characterized by the continuous influx and egress of highly motile cells. Cell clusters and entire colonies were observed to locomote and on several occasions fuse to form larger structures. Macrophagelike cells located centrally within colonies appeared to play a major role in such behavior. Taken together these results conclusively demonstrate that, in the present system, lymphocyte colonies are the product of a complex pattern of cell interaction, proliferation, and cell motility and, as such, are polyclonal in origin.

Adult↗
PubMed1984

Toxicity testing of pertussis vaccines: effect of increased sensitivity of mice to Bordetella pertussis.

The increased sensitivity to Bordetella pertussis of a line of CD-1 mice used in toxicity-testing and the consequent and needless rejection of several lots of DPT vaccine are described. Apart from changes in the mice the possible presence of an infective agent in the animal house could not be discounted. The usefulness of individual mouse weights in the assay as opposed to group weights and of a reference preparation to monitor the performance of mice is discussed.

Animals↗
PubMed1984

Theoretical bases for vascular selectivity of Ca2+ antagonists.

The purpose of these studies was to characterize mechanisms of activation of vascular tissues in order to clarify possible theoretical bases for Ca2+-antagonist (CAt) selectivity. Activation of rabbit aorta, mesenteric artery, and mesenteric resistance vessels by agonists and depolarizing potassium (K+) solution, and inhibition by CAts were studied by measurement of contractions, 45Ca fluxes, and membrane potentials (via intracellular electrodes). We found that the CAts studied (D-600, diltiazem, and nisoldipine) inhibited K+-induced Ca2+ influx and contractions in a closely correlated manner, suggesting inhibition of Ca2+ entry as their primary, if not sole, mechanism of action. Diltiazem and nisoldipine had no effect on intracellular Ca2+ release or on the contractile protein system. The following evidence was obtained to support the tenet that norepinephrine (NE) and 80 mM K+ open two distinct Ca2+ channels, one receptor-operated (ROC) and the other potential-operated (POC): (a) NE activated the rabbit aorta without eliciting a change in membrane potential; (b) NE activation of the rabbit mesenteric resistance vessels was accompanied by membrane depolarization, but this depolarization was blocked by 10(-5) M diltiazem, whereas that induced by 80 mM K+ was not; (c) 45Ca influx stimulated by 80 mM K+ and that stimulated by a maximal [NE] were additive when the two agents were administered together in the aorta and the resistance vessels; (d) the Ca2+-channel agonist Bay K8644 opens the POC but not the ROC in rabbit aorta, as it is capable of stimulating Ca2+ influx in addition to 10(-5) M NE, but not to 80 mM K+; (e) the CAts show selective inhibition of the POC over the ROC in the aorta, whereas diltiazem preferentially inhibits the ROC in the resistance vessels; and (f) alpha adrenoreceptor occupation, phosphodiesterase inhibition, or dibutyryl cyclic AMP selectively inhibits the POC over the ROC in the aorta.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

Cloning of Bordetella pertussis outer membrane proteins in Escherichia coli.

We constructed and screened a gene bank of phase I chromosomal DNA of Bordetella pertussis in Escherichia coli. A single immunopositive clone was recovered, and the hybrid plasmid obtained, designated pFSH200, had a molecular size of 46.6 kilobases. Smaller derivatives were generated by partial digestion of plasmid pFSH200 and were further characterized. One such derivative, plasmid pFSH201, contained a 4.5-kilobase chromosomal DNA fragment of B. pertussis which coded for the synthesis of the two outer membrane proteins of 33 and 30 kilodaltons specific to B. pertussis.

Bacterial Outer Membrane Proteins↗