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Biomedical subjects

J B Forrest

Publications and source records attributed to J B Forrest.

At least 73 records · Page 4Linked to original sources
PubMed1980

The response to epidural steroid injections in chronic dorsal root pain.

Thirty-seven patients with long-standing post-herpetic neuralgia and 27 with post-traumatic neuralgia (PTN) were treated with three epidural injections each of methylprednisolone acetate (Depo Medrol) given at weekly intervals. Differential subarachnoid or epidural block was done in all patients and placebo responders were excluded from the study. Mean age, duration of symptoms, and pain intensity measured by visual analogue scale were similar in both groups. Visual analogue scale ratings were reduced one month after treatments from both groups. Visual analogue scale ratings were reduced one month after treatments from pretreatment values of 84.4 and 78.7 to 9.6 and 15.2 in the post-herpetic and post-traumatic groups respectively, and were further reduced to 4.6 and 11.6 respectively after one year when 89 per cent of patients in the post-herpetic group and 59 per cent of patients in the post-traumatic group were completely pain free. Side effects were minor in all cases. It is suggested that this is the treatment of choice in post-herpetic and post-traumatic neuralgia where steroid administration is not contraindicated.

Adult↗
PubMed1980

Dimensional changes of cultured smooth muscle cells due to preparatory processes for transmission electron microscopy.

The change in volume of cultured smooth muscle cells prepared with four different fixation procedures for transmission electron microscopy was studied. Although the cells showed swelling after being embedded in Spurr's embedding medium, the degree of swelling depended on the particular method of fixation procedure used. When the volume of the cells measured using transmission electron microscopy was compared with that of the fresh cell volume, cells prepared by two of the methods showed swelling, and cellular shrinkage was noted in the other two methods. One method which caused the least amount of volume change is recommended for quantitative electron microscopic study of vertebrate smooth muscle cell systems.

Animals↗
PubMed1980

Immotile cilia syndrome in persons with and without Kartagener's syndrome.

We studied the ultrastructure and function of respiratory tract cilia in a group of patients with Kartagener's Syndrome, and compared the results with those from a group of subjects with unexplained histories of chronic bronchiectasis and bronchitis. Both patient groups lacked pulmonary and nasal mucociliary transport. On electron microscopic examination of nasal mucosal biopsy tissue, all patient specimens had abnormal cilia with a highly disorganized microtubular network, and a consistent absence of dynein arms. Cilia from both groups were immotile when viewed under direct phase contrast, but could be animated by the addition of 10(-6) g/ml of ATP or ATPase to the same degree of spontaneous motility seen in normal cilia. Immotile cilia syndrome clearly includes not only patients with Kartagener's syndrome, but also some patients with chronic bronchitis and bronchiectasis.

Adenosine Triphosphatases↗
PubMed1980

The dyskinetic cilia syndrome. Ciliary motility in immotile cilia syndrome.

Ciliary motility was studied in three patients with Kartagener syndrome who had previously been found to have absent nasal and pulmonary mucociliary transport and missing dynein arms in nasal cilia. A video system was used to record movement of cilia obtained by nasal brushings for analysis of wave form and beat frequency. Two patterns of abnormal ciliary beat were observed; an oscillating and a rotating type of motion. There was no evidence of planar coordination of metachronicity. This abnormal motion was present in up to 40 percent of cells and the remainder were totally immotile. Thus, in Kartagener syndrome many ciliated cells are motile, but the motion is abnormal. We suggest that "immotile cilia syndrome" is a misnomer, and recommended it be renamed "dyskinetic cilia syndrome."

Adenosine Triphosphatases↗
PubMed1979

Effect of halothane on the pulmonary vascular response to hypoxia in dogs.

The pulmonary vascular response to alveolar hypoxia with and without halothane exposure was measured in dogs. Hypoxia increased pulmonary artery pressure (Ppa) and pulmonary vascular resistance (PVR) so that in each case inverse linear relationships were found with arterial oxygen saturation. These responses were highly significant and reproduceable but varied greatly between individuals. Halothane administration resulted in an increased slope of PVR against oxygen saturation due to the fact that reduction in cardiac output exceeded the reduction in Ppa. An analysis of variance showed that it was possible to predict accurately the hypoxic PVR and Ppa responses under halothane anaesthesia from the control hypoxic responses. Animals with low PVR responses showed the greatest arterial oxygen desaturation with hypoxia, whereas high responders showed least oxygen desaturation. Thus it was possible to predict those individuals at risk from severe arterial oxygen desaturation under halothane anaesthesia.

Animals↗
PubMed1979

A simple method of percutaneous cannulation of the pulmonary artery in small mammals.

A simple technique for catheterization of the pulmonary artery in small mammals is described. An angled polypropylene introducer is used to allow easy placement of Swan--Ganz and triple lumen thermistor tipped catheters for haemodynamic evaluation. Hitherto such information has been unavailable because of difficulties in placement of catheters as well as an unacceptably high mortality rate. In an extensive experience with this new technique no instances of cardiac arrhythmia or of death have so far been encountered.

Animals↗
PubMed1979

Activation of nasal cilia in immotile cilia syndrome.

Nasal biopsy specimens were obtained from 5 normal subjects and from 7 patients with immotile cilia syndrome. Of the latter, 3 had Kartagener's syndrome, one had Kartagener's forme fruste, and 3 had bronchiectasis and sinusitis. An in vitro motility test was used to assess ciliary movement. Exogenous adenosine triphosphate and adenosine triphosphatase activated the immotile cilia to levels equal to or slightly greater than the spontaneous activity seen in normal subjects. Absence of dynein arms on ciliary peripheral microtubule doublets was a consistent finding in the patients' specimens and is suggested to be the basic defect in this syndrome that is responsible for immotility and absence of mucociliary clearance.

Adenosine Triphosphatases↗
PubMed1979

Structural aspects of gas exchange.

The lung is composed of several million small air spaces, lined by a delicate tissue membrane separating air from capillary blood. The design features of the gas exchange region in the lung are optimal for gaseous diffusion, by having a very extensive contact surface but with a minimal tissue barrier composed of an epithelial and endothelial layer separating an interstitial layer. The extent of the gas exchange surface in adult lungs is determined by general maturation which in turn is influenced by metabolic requirements of the organism. Environmental factors can modulate the pattern of ultimate lung development. Lung inflation causes air spaces to expand mainly by a process of tissue unfolding beneath an extremely thin layer of alveolar surfactant. This ensures cellular integrity during extreme deformations while at the same time providing a reserve of gas exchange surface so that functional diffusion capacity at all lung volumes is less than the structural maximum.

Animals↗
PubMed1978

Management of chronic dorsal root pain with epidural steroid.

Twenty-eight patients presenting with typical dorsal root pain of more than six months' duration were given a series of three epidural injections of methylprednisolone acetate. The patients were grouped according to known aetiologic factors. Improvement in symptoms was most marked in the post-herpetic group where 86% were free of pain after six months. In the post-trauma/surgical group, 50% of patients were free of pain after six months, while in the idiopathic group only minimal improvement occurred. The side-effects of steroid administration into the epidural space were in all cases minor.

Adult↗
PubMed1978

Variability of the pulmonary vascular response to hypoxia and relation to gas exchange in dogs.

Anaesthetized and mechanically ventilated dogs were subjected to five minutes of alveolar hypoxia with Fio2 ranging from 0.08 to 0.20 while pulmonary artery pressure (Ppa), pulmonary wedge pressure (Pwp) and cardiac output (Q) were measured. Hypoxia increased Ppa in all dogs whereas Pwp and Q did not change significantly. Thus pulmonary vascular resistance (PVR) increased by a mean for all dogs of 56 per cent. There was great variation in the absolute increase in Ppa and PVR between animals and these were not statistically correlated with arterial Po2, but highly significant and reproduceable inverse relationships were found for Ppa and PVR against arterial oxygen per cent saturation. The slopes of these responses varied between dogs from -0.013 to -0.144 for PVR and from -0.038 to -0.561 for Ppa. The alveolar-arterial oxygen gradient and the pulmonary shunt fraction were reduced in a similar way with decreasing arterial oxygen per cent saturation, but dead space/tidal volume ratio remained unchanged. Thus the slope of PVR response to hypoxia against arterial oxygen per cent saturation is unique for individual animals. This may reflect functional and likely structural adaptations of the pulmonary vascular smooth muscle.

Animals↗
PubMed1978

The current status of anaesthesia research in Canada.

The Association of Canadian University Departments of Anaesthesia (A.C.U.D.A.) surveyed all 16 university departments during 1975/76/77, to obtain detailed and accurate information on manpower and research activities. The results of this survey have been summarized and show that only 0.68 per cent of federal MRC funds support anaesthesia research compared with 3.29 per cent of the U.S. federal N.I.G.M.S. funds. Notably 90 per cent of Canadian research funds are held in three departments. Canadian academic anaesthetists spend twice as much time in clinical service as their U.S. counterparts and there are 46 per cent fewer full-time faculty and 64 per cent fewer researchers in Canadian departments of Anaesthesia as compared to the U.S. A number of recommendations are made which will be acted upon as a basis for future planning.

Anesthesiology↗