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Biomedical subjects

H M Thomas

Publications and source records attributed to H M Thomas.

At least 73 records · Page 4Linked to original sources
PubMed1990

Pulmonary rehabilitation in lung disease other than chronic obstructive pulmonary disease.

The benefit of pulmonary rehabilitation is well documented for patients with chronic obstructive pulmonary disease (COPD). However, such benefit has not been demonstrated for severely impaired patients with other chronic pulmonary diseases. Occasional non-COPD patients have been admitted to our 4-wk inpatient program. We compared the improvement of these non-COPD patients with that of COPD patients in the same program. Improvement is assessed by a 6-min walk test done at admission and discharge. On the admission 6-min walk test, 32 non-COPD patients had an ambulation distance of 276 +/- 219 ft (SD). At completion of the program, their ambulation distance increased to 574 +/- 367 ft (increase in ambulation 298 +/- 290 ft, P less than 0.0001). Diagnostic subgroups improved to essentially the same extent. The increase in ambulation was not statistically different between non-COPD patients and a series of 317 patients with COPD. Patients severely impaired with chronic pulmonary disease other than COPD benefit from intensive pulmonary rehabilitation, and the degree of improvement is similar to that of COPD patients.

Blood Gas Analysis↗
PubMed1990

Induction of lactogenic receptors in liver of hypophysectomized rats treated with bovine growth hormone-monoclonal antibody complexes.

Male hypophysectomized rats treated with bovine (b)GH-monoclonal antibody complexes showed enhanced weight gain compared with animals treated with bGH alone over a 12-day treatment period. Liver microsomes prepared from animals showing enhanced weight gain exhibited increased specific binding of human (h)GH. Studies on the specificity of these binding sites showed that they were lactogenic, 125I-labelled hGH being displaced by ovine prolactin, but not by non-mammalian growth hormones. In this respect they were similar to lactogenic binding sites in the liver of pregnant rats. Monoclonal antibodies to hGH blocked binding to lactogenic receptors to different extents. The pattern of such inhibition was similar, but not identical, for the receptors induced in hypophysectomized rats and those from pregnant rat liver. The evidence available suggests that the lactogenic receptors induced by bGH-monoclonal antibody complexes are not directly involved in the enhancement of growth.

Animals↗
PubMed1989

Antagonism of leukotriene receptors and administration of a 5-lipoxygenase inhibitor do not affect hypoxic vasoconstriction.

The role of leukotrienes in hypoxic vasoconstriction remains controversial. Our previous study using the lipoxygenase inhibitor BW 755C in dogs failed to show a substantive role for leukotrienes in hypoxic vasoconstriction. To clarify further the role of leukotrienes, we designed 3 protocols. In the first protocol, we examined the effects of LTD4 boluses on the pulmonary circulation in 6 anesthetized dogs. LTD4, 1 microgram/kg, (a large dose relative to other species) produced no detectable constriction of the pulmonary artery, while systemic vascular resistance increased 41 +/- 17% (SD), left atrial pressure rose 3.5 +/- 1.5 mmHg, and cardiac output fell 18 +/- 8%. Two leukotriene receptor antagonists, LY171883 and L-648051, decreased these effects by more than 50%. In the second protocol, we tested these antagonists in 7 anesthetized, paralyzed, closed-chest dogs with acute left lower lobe atelectasis. Two manifestations of hypoxic vasoconstriction were examined: shunt fraction (as an inverse indicator of regional constriction in response to local hypoxia) and the pulmonary pressor response to global alveolar hypoxia (as an index of general hypoxic vasoconstriction). During normoxia before administration of the inhibitor, shunt fraction, measured using an SF6 infusion, was 25 +/- 7%. The pulmonary pressor response to hypoxia, defined as the increase in pulmonary end-diastolic gradient (PDG) produced by 10% O2 inhalation, averaged +10.5 +/- 3.6 mmHg. The increase in pulmonary vascular resistance (PVR) with hypoxia was +2.4 +/- 1.7 mmHg/L/min. Then, during normoxia, 1 of the 2 antagonists was administered. Shunt fraction was unchanged (26 +/- 4%; p = 0.5). The pressor response to hypoxia was slightly less but remained substantial (the increase in PDG with hypoxia was +7.9 +/- 2.8 mmHg; p less than 0.05; the increase in PVR was +1.8 +/- 1.2 mmHg/L/min, p less than 0.10). In the third protocol we gave RG 5901, a relatively specific 5-lipoxygenase inhibitor, to 5 dogs with lobar atelectasis. The indices of hypoxic vasoconstriction were not affected by RG 5901. Shunt fraction was 29.5 +/- 8.1% before and 27.0 +/- 7.4% after RG 5901 (p greater than 0.05). The pressor response to hypoxia was +8.9 +/- 2.1 mmHg before and +8.7 +/- 3.7 mmHg after RG 5901 (p greater than 0.05). We conclude that in dogs, hypoxic vasoconstriction does not appear to be mediated by leukotrienes.

Acetophenones↗
PubMed1989

Acute pulmonary edema associated with the use of oral ritodrine for premature labor.

We describe a patient who developed acute pulmonary edema while taking oral ritodrine for the treatment of premature labor and recovered after its discontinuation. The mechanism of development of pulmonary edema associated with beta-sympathomimetic agents is still not fully understood. Patients taking oral ritodrine should be observed for cardiopulmonary signs and symptoms.

Acute Disease↗
PubMed1989

Percutaneous laser-assisted balloon angioplasty of lower-extremity arterial disease in a free-standing laboratory: clinical experience with 100 cases.

From September 1987 through May 1988, 86 patients (62 men and 24 women) underwent percutaneous laser-assisted balloon angioplasty, and 2 patients (1 man and 1 woman) underwent laser-assisted balloon angioplasty via cutdowns, in our free-standing catheterization laboratory. The patients' ages ranged from 36 to 81 years. One hundred limbs were treated; each had at least 1 total occlusion, and many had multiple significant occlusions (greater than 50%). Vascular access was attained via the common femoral artery in 62 limbs, via the popliteal artery in 34 limbs, and via a posterior tibial artery cutdown in 4 limbs. In all, 232 lesions were treated either by percutaneous laser-assisted balloon angioplasty (172 lesions) or by balloon angioplasty alone (60 lesions). Technical success was defined as "recanalization and dilation of the occluded arterial segment, resulting in a recognizable improvement in pulse that persisted until hospital discharge." The technical success/attempt ratios for the 172 laser-assisted treatments were as follows: iliac artery, 11/17 (64.7%); common femoral artery, 8/9 (88.9%); superficial femoral artery, 62/80 (77.5%); popliteal artery, 25/30 (83.3%); peroneal artery, 14/16 (87.5%); anterior tibial artery, 6/7 (85.7%); and posterior tibial artery, 9/13 (69.2%). Technical failure occurred in 25 limbs. Failure was not related to sex, age, approach artery, or diabetes, but it was related to the indication of impending limb loss (p < 0.01), previous vascular surgery (p < 0.01), amputation (p < 0.01), and lesion length of 20 cm or greater. Clinical success was defined as "clinical improvement in symptoms, with persistence of an improved pulse at follow-up." Recurrence was observed in 10 limbs. Recurrence was not related to sex, age, approach artery, diabetes, or lesion length, but it was related to the indication of impending limb loss (p < 0.05); to the fact that the patient was a cigarette smoker at the time of the procedure (p < 0.02); and (inversely) to the number of tibial vessels that remained patent post-intervention. Five patients required emergency surgery after laser-assisted angioplasty, but no limb amputation has been necessary. Minor complications included perforation (16 cases), hematoma formation (6 cases), dissection (3 cases), hemorrhage (1 case), hives (1 case), and fracture of the laser probe (1 case). We conclude that percutaneous laser-assisted balloon angioplasty can be safely accomplished in a free-standing laboratory and that the procedure is reasonably successful in patients with totally occluded lower-extremity arteries.

Journal Article↗
PubMed1988

Pulmonary rehabilitation in COPD patients with elevated PCO2.

Exercise programs are a mainstay of pulmonary rehabilitation for COPD. COPD patients with elevated PCO2 are severely impaired and might benefit from rehabilitation more than other patients. However, there is no systematic data to indicate that hypercapnic COPD patients benefit from intensive rehabilitation. Indeed, in patients with hypercapnia, increased exercise might overtax respiratory muscles, which are weak relative to those of eucapnic patients. To investigate this issue, we reviewed all COPD patients admitted to our pulmonary inpatient program from 1983 to 1986 (n = 317). The program includes multiple daily sessions of upper and lower extremity exercise to tolerance. We assessed admission and discharge pulmonary function tests, arterial blood gases (room air), and functional status. Ambulation distance on a 6-min walk test was used as an objective measure of functional status. Patients were grouped according to the results of their admission room air PCO2. We found that eucapnic patients (n = 197) significantly increased ambulation (admission to discharge) from 409 to 816 feet (p less than 0.001). Hypercapnic patients improved as well. Patients with moderate hypercapnia (PCO2, 45 to 54 mm Hg; n = 86) increased their ambulation from 330 to 663 feet (p less than 0.0001). Patients with severe hypercapnia (PCO2 greater than 54 mm Hg; n = 34) increased their ambulation from 336 to 597 feet (p less than 0.0001). We found a small but significant improvement in discharge pulmonary function and arterial blood gas results. We conclude that COPD patients with hypercapnia, despite severe ventilatory impairment and weak respiratory muscles, tolerate exercise well and benefit significantly from intensive inpatient pulmonary rehabilitation.

Carbon Dioxide↗
PubMed1988

The toxic effects of alpha-chloralose.

1. Alpha-chloralose, formed by the condensation of glucose with chloral, is used as a rodenticide and in the control of bird pests. 2. In two cases of poisoning with alpha-chloralose the clinical features included coma and generalized convulsions resembling the effects of strychnine more than those of chloral hydrate. 3. The principles of management are the support of vital functions in the unconscious patient and removal of unabsorbed poison by gastric lavage. Diazepam may be used to control convulsions.

Adolescent↗
PubMed1987

Lipoxygenase and cyclooxygenase blockade by BW 755C enhances pulmonary hypoxic vasoconstriction.

Lipoxygenase products (leukotrienes) have been proposed as the mediators of pulmonary hypoxic vasoconstriction. However, the supporting data are inconclusive because the lipoxygenase and leukotriene receptor blockers that reduce hypoxic vasoconstriction (such as diethylcarbamazine and the FPL's) have confounding effects. We investigated BW 755C, a potent inhibitor of both lipoxygenase and cyclooxygenase, in eight intact anesthetized dogs with acute left lower lobe atelectasis. We examined two manifestations of hypoxic vasoconstriction: shunt fraction, as an inverse indicator of regional constriction in response to local hypoxia, and the pulmonary pressor response to global alveolar hypoxia, as an index of general hypoxic vasoconstriction. During normoxia, shunt fraction, measured using a sulfur hexafluoride infusion, was 32.0 +/- 7.0%. The pulmonary pressor response to hypoxia, defined as the increase in pulmonary end-diastolic gradient produced by 10% O2 inhalation, averaged 4.5 +/- 1.8 mmHg. Then, during normoxia, BW 755C was administered. Shunt fraction fell in all eight dogs from the previous mean of 32% to 25.5 +/- 6.1% (t = 6.5, P less than 0.0005). The hypoxic pressor response rose in all dogs, from the previous 4.5 mmHg to 9.0 +/- 3.5 mmHg (t = 4.5, P less than 0.005). BW 755C enhances hypoxic vasoconstriction, an effect consistent with its activity as a cyclooxygenase inhibitor. These data do not support a substantive role for the lipoxygenase pathway in hypoxic vasoconstriction.

4,5-Dihydro-1-(3-(trifluoromethyl)phenyl)-1H-pyraz↗
PubMed1985

Right ventricular visualization by thallium 201 myocardial scintigraphy in chronic obstructive pulmonary disease.

The right ventricle is not normally displayed by studies with thallium 201 in patients at rest, but it can be shown by thallium 201 myocardial scintigraphy with pressure or volume overload of the right ventricle and with right ventricular hypertrophy. We sought to determine the frequency of right ventricular demonstration by thallium 201 in 20 patients at rest, who had chronic obstructive pulmonary disease of varying severity studied at baseline. The ventricle was viewed in 11 of 20 patients (55%); these patients had significantly lower values for forced expiratory volume in one second (FEV1) and PO2. Eight patients had catheterization of the right side of the heart; mean pulmonary artery pressure and pulmonary vascular resistance were significantly higher in patients with right ventricular visualization. We conclude that thallium 201 scintigraphy frequently shows the right ventricle in patients with chronic obstructive pulmonary disease and that such visualization correlates with the severity of the ventilatory defect and with pulmonary hypertension.

Aged↗
PubMed1985

Relation of prostanoids to strength of hypoxic vasoconstriction in dogs with lobar atelectasis.

In dogs with acute lobar atelectasis, meclofenamate administration decreases shunt fraction uniformly and moderately without abolishing the wide variation of strength of hypoxic vasoconstriction and resultant variability of shunt fraction (J. Appl. Physiol. 54: 284-289, 1983). To further assess the role of prostanoids, we measured prostanoid metabolites as well as shunt fraction and pressor response to alveolar hypoxia. In six intact anesthetized dogs with acute left lower lobe atelectasis, shunt fraction during normoxia was measured with SF6. Levels of 6-ketoprostaglandin F1 alpha (6-keto-PGF1 alpha) and thromboxane B2 in arterial, mixed venous, and left lower lobe venous blood were measured with the double antibody radioimmunoassay technique. Ten percent O2 was administered to assess pressor response. Twenty-one percent O2 was restarted, meclofenamate was administered, and measurements were repeated 30 min later. Atelectasis did not elevate levels of prostanoid metabolites. 6-Keto-PGF1 alpha averaged 88 +/- 65 pg/ml prior to atelectasis and 81 +/- 73 pg/ml after atelectasis (F = 0.7, P = NS). Likewise, thromboxane B2 values were normal. No transpulmonary concentration differences were found. 6-Keto-PGF1 alpha did not correlate with shunt values, which ranged from 14 to 35% (mean 21%). Meclofenamate effectively blocked cyclooxygenase, as demonstrated by decreases in prostanoid metabolite levels. It seems likely that in dogs with acute atelectasis prostacyclin localized in the pulmonary vasculature decreases strength of hypoxic vasoconstriction modestly and uniformly without raising blood levels of prostacyclin metabolite.

6-Ketoprostaglandin F1 alpha↗
PubMed1984

Computed tomographic demonstration of displaced right upper lobe bronchus in an adult woman with congenital heart disease.

To our knowledge, this is the first description of the computed tomographic appearance of a displaced right upper lobe bronchus. The case reported is that of a 43 year-old woman who had known congenital heart disease and systemic hypertension. The computed tomographic study demonstrated a displaced right upper lobe bronchus; a persistent left superior vena cava; pulmonary hypertension with associated dilatation of the right chambers of the heart consistent with a longstanding left to right shunt; and subsequent development of pulmonary hypertension.

Abnormalities, Multiple↗