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Biomedical subjects

M Jackson

Publications and source records attributed to M Jackson.

At least 271 records · Page 15Linked to original sources
PubMed1991

Role of tachykinins in hyperpnea-induced bronchovascular hyperpermeability in guinea pigs.

Isocapnic dry gas hyperpnea causes bronchoconstriction in guinea pigs that is mediated by release of tachykinins from airway sensory nerves. Exogenous neuropeptides can induce microvascular leak. Therefore we tested whether dry gas hyperpnea also elicits bronchovascular hyperpermeability by measuring Evans blue-labeled albumin extravasation along the airways of mechanically ventilated guinea pigs. We found that 1) room temperature dry gas hyperpnea increased Evans blue extravasation in extrapulmonary and intrapulmonary airways as a specific consequence of local airway heat/water losses, 2) capsaicin pretreatment ablated the bronchoconstrictor response to dry gas hyperpnea and reduced bronchovascular leak only in intrapulmonary airways, 3) phosphoramidon given to capsaicin-pretreated animals partially restored dry gas hyperpnea-induced bronchoconstriction and increased the vascular hyperpermeability response to hyperpnea in intrapulmonary airways, and 4) propranolol administration had no important effects on any of these airway responses. We conclude that dry gas hyperpnea causes bronchovascular hyperpermeability in guinea pigs. Tachykinins have a dominant role in this response in the intrapulmonary airways, although another mechanism may also contribute to the microvascular leak in the extrapulmonary airways.

Animals↗
PubMed1991

Dunaimycins, a new complex of spiroketal 24-membered macrolides with immunosuppressive activity. I. Taxonomy of the producing organisms, fermentation and antimicrobial activity.

The dunaimycins are a new complex of spiroketal 24-membered macrolides discovered in the fermentation broth of two actinomycetes. Based on taxonomic studies these two cultures, which were isolated from soil, were identified as Streptomyces diastatochromogenes strains AB 1691Q-321 and AB 1711J-452. The dunaimycins possess both immunosuppressive and antimicrobial activity.

Anti-Bacterial Agents↗
PubMed1990

Comparison of two triphasic contraceptives with different progestogens: effects on metabolism and coagulation proteins.

This study compared the effects of two triphasic oral contraceptives (OCs) taken for 6 pill cycles. One preparation contained levonorgestrel (EE/LN), the other a new progestagen, gestodene (SHG 415G). There were no effects on body weight, dietary habits, blood pressure, HDL-cholesterol or carbohydrate metabolism. Both OCs caused a small but statistically significant increase in plasma total cholesterol, LDL-cholesterol, LDL/HDL-cholesterol ratio and triglyceride concentration. Sex hormone binding globulin was increased by both preparations. Coagulation factor VII and fibrinogen were increased and antithrombin III levels reduced, indicating that both preparations had pro-coagulant activity. The gestodene triphasic preparation was associated with minor side effects similar to those experienced on EE/LN. The metabolic effects were similar despite the lower total steroid dose of the gestodene preparation.

Adolescent↗
PubMed1990

Leucocyte mobilization and release of neutrophil elastase following acute insulin-induced hypoglycaemia in normal humans.

Insulin-induced hypoglycaemia in humans is associated with the rapid mobilization of leucocytes in peripheral blood. The aim of the present study was to determine whether neutrophil activation, manifested in plasma by neutrophil elastase concentration, occurs in response to insulin-induced hypoglycaemia. Acute hypoglycaemia (mean blood glucose 1.3 +/- 0.2 mmol l-1; mean +/- SD) was induced with intravenous insulin in 15 normal human subjects, and provoked an increase in the neutrophil count from 3.4 (range 1.9-6.5) to 10.7 (9.4-16.3) X 10(9) l-1 (p less than 0.001), and in the total leucocyte counts from 5.7 (4.1-8.1) to 12.8 (11.3-18.6) X 10(9) l-1 (p less than 0.001), with associated elevations in plasma neutrophil elastase concentration from 21 (12-34) to 29 (14-70) micrograms l-1 (p less than 0.05), and in total neutrophil elastase concentration from 5.90 (3.13-8.20) to 25.20 (23.00-52.00) mg l-1 (p less than 0.001). As neutrophil elastase is implicated in the development of vascular disease, this rise in response to hypoglycaemia may be of pathological importance in insulin-treated diabetic patients.

Adult↗
PubMed1990

Leucocyte arylsulphatase A activity and subtypes of chronic schizophrenia.

Previous studies have suggested that arylsulphatase A (ASA - the biochemical marker of metachromatic leucodystrophy) deficiency may be present in a sizeable proportion of patients with chronic psychosis. This study surveyed leucocyte ASA activity in a group of chronic psychotic patients and compared ASA activity in 3 subgroups fulfilling Research Diagnostic Criteria for schizophrenia (undifferentiated), paranoid schizophrenia and schizoaffective psychosis. Three of 45 patients had significantly reduced ASA activity but none had metachromatic leucodystrophy. Although ASA levels did not differ significantly between the groups, schizophrenics without a family history of schizophrenia had significantly lower ASA levels than those with. The implications of these findings are discussed.

Adult↗
PubMed1990

Inflammatory response, neutrophil activation, and free radical production after acute myocardial infarction: effect of thrombolytic treatment.

Activated neutrophils releasing proteolytic enzymes and oxygen free radicals have been implicated in extending myocardial injury after myocardial infarction. Neutrophil elastase was used as a marker of neutrophil activation and the non-peroxide diene conjugate of linoleic acid was used as an indicator of free radical activity in 32 patients after acute myocardial infarction; 17 were treated by intravenous thrombolysis. Patients with acute myocardial infarction had higher plasma concentrations of neutrophil elastase and the non-peroxide diene conjugated isomer of linoleic acid than normal volunteers or patients with stable ischaemic heart disease. Patients treated by thrombolysis had an early peak of neutrophil elastase at eight hours while those who had not been treated by thrombolysis showed a later peak 40 hours after infarction. The plasma concentration of non-peroxide conjugated diene of linoleic acid was highest 16 hours after the infarction irrespective of treatment by thrombolysis. Quantitative imaging with single photon emission tomography showed decreased uptake of indium-111 labelled neutrophils in the infarcted myocardium (as judged from technetium-99m pyrophosphate) in those who had received thrombolysis, suggesting a decreased inflammatory response. The results indicate increased neutrophil activation and free radical production after myocardial infarction; they also suggest that thrombolysis does not amplify the inflammatory response and may indeed suppress it.

Adult↗
PubMed1990

Operative findings after percutaneous pulmonary balloon dilatation of the right ventricular outflow tract in tetralogy of Fallot.

Since 1983 percutaneous balloon dilatation of the right ventricular outflow tract has been performed as an alternative to surgical palliation in selected cases of tetralogy of Fallot at the Royal Liverpool Children's Hospital. From 31 December 1984 to 31 December 1988, 27 of these patients underwent subsequent surgical correction. Age at operation ranged from 7 to 58 months (median 2.7 years). The mean interval between balloon dilatation and correction was 15.6 months (range 3-39 months). Two patients had a systemic pulmonary shunt operation performed before dilatation and a further five required one afterwards. Overall 20 (74%) patients had some anatomical alteration as the result of balloon dilatation, while in seven (26%) there was no discernible change in the right ventricular outflow tract. There was no consistent relation between the ratio of balloon size to pulmonary annulus diameter and the morphological findings. Balloon dilatation may obviate the need for systemic-pulmonary shunt at the expense of some structural damage, particularly to the posterior cusp. The present data suggest that dilatation does not bring about growth of the annulus to such an extent that transannular patch is no longer needed at intracardiac repair.

Catheterization↗
PubMed1990

Distribution of airway narrowing during hyperpnea-induced bronchoconstriction in guinea pigs.

Increasing minute ventilation of dry gas shifts the principal burden of respiratory heat and water losses from more proximal airway to airways farther into the lung. If these local thermal transfers determine the local stimulus for bronchoconstriction, then increasing minute ventilation of dry gas might also extend the zone of airway narrowing farther into the lung during hyperpnea-induced bronchoconstriction (HIB). We tested this hypothesis by comparing tantalum bronchograms in tracheostomized guinea pigs before and during bronchoconstriction induced by dry gas hyperpnea, intravenous methacholine, and intravenous capsaicin. In eight animals subjected to 5 min of dry gas isocapnic hyperpnea [tidal volume (VT) = 2-5 ml, 150 breaths/min], there was little change in the diameter of the trachea or the main stem bronchi up to 0.75 cm past the main carina (zone 1). In contrast, bronchi from 0.75 to 1.50 cm past the main carina (zone 2) narrowed progressively at all minute ventilations greater than or equal to 300 ml/min (VT = 2 ml). More distal bronchi (1.50-3.10 cm past the main carina; zone 3) did not narrow significantly until minute ventilation was raised to 450 ml/min (VT = 3 ml). The estimated VT during hyperpnea needed to elicit a 50% reduction in airway diameter was significantly higher in zone 3 bronchi [4.3 +/- 0.8 (SD) ml] than in zone 2 bronchi (3.5 +/- 1.1 ml, P less than 0.012).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

The effect of restrictive and compensatory growth on the incidence of leg abnormalities and performance of commercial male turkeys.

To determine if excessive body weight and dietary protein and amino acid intake contribute to the incidence of leg deformities, the growth of male turkeys was restricted from 6 to 12 wk and from 6 to 20 wk of age by feeding diets for ad libitum intake that were low in dietary protein and amino acids (74% of controls). For those turkeys whose growth was restricted from 6 to 12 wk of age, a return to control diets (low compensatory plane) or to 20% above control diets (high compensatory plane) with respect to protein and amino acids resulted in live body weights comparable with controls at 20 wk of age. Feed to gain ratios (0 to 20 wk) were comparable between compensated and control birds, and protein efficiency was improved for birds fed the low compensatory plane diets. Restricting growth significantly lowered the incidence of leg abnormalities at 12 wk of age (P less than .05), as compared with controls, but by 20 wk, only birds fed the low compensatory plane diet showed a lowered incidence (P less than .06). These results on leg abnormalities (mainly valgus-varus deformities) suggest that rapid weight gains or dietary protein and amino acid intake may contribute to the leg weakness syndrome but is certainly not the only factor involved.

Amino Acids↗
PubMed1990

The effect of compensatory growth on carcass characteristics of male turkeys.

Male turkeys were fed for ad libitum intake dietary levels of protein and amino acids at 74% of controls from 6 to 12 wk of age. The treatment in which birds were returned to control rations from 12 to 20 wk of age was designated as the low compensatory plane dietary regimen. Turkeys given diets with protein and amino acids at levels 20% above those in control diets from 13 to 20 wk of age were referred to as the high compensatory plane dietary regimen. By 20 wk of age, realimentation had successfully resulted in live body weights comparable with those of controls, but carcass weights were significantly lower in birds fed the low and high compensatory plane diets. Percentage yield of drums, wings, shell, as well as skin and fat did not differ among dietary treatments. Lowered protein and amino acid consumption from 6 to 12 wk of age caused lighter breast and breast muscle weights at 20 wk of age. The percentage yield of breast and breast muscle declined, and thigh and thigh muscle increased for the birds fed the low compensatory plane diet when compared with the controls. The birds fed the low compensatory plane diet were placing a greater proportion of their weight gains during realimentation on thigh muscle rather than breast muscle deposition. Compensatory growth did not affect the absolute length or width of the tarsometatarsus or testes weights at 20 wk of age.

Amino Acids↗
PubMed1990

Cell populations in the human early pregnancy decidua: natural killer activity and response to interleukin-2 of CD56-positive large granular lymphocytes.

Large granular lymphocytes (LGL) have been shown previously to be the most abundant cell type in the first trimester human decidua. Purified populations of decidual LGL were prepared by flow cytometry of cell dispersions labelled with NKH1 (CD56), an antibody specific for peripheral blood LGL, and the functional properties of CD56-positive cells, CD56-negative and unsorted decidual cells compared. Both CD56-positive cells and unsorted decidual cells have cytotoxic activity against the natural killer (NK) cell target K562 which was weak compared with that of peripheral blood mononuclear cells (PBMC). The CD56-negative cells had no cytotoxic activity against K562. All three decidual cell populations proliferated in response to recombinant human interleukin-2 (rIL-2), but none produced detectable levels of IL-2 in culture. When unsorted decidual cells were cultured for 7 days in rIL-2 the proportion of CD56-positive cells increased and NK activity against K562 was augmented. The NK activity of purified CD56-positive decidual cells was also augmented by culturing in rIL-2. The potential role of decidual LGL in regulating the development of the semi-allogeneic placenta is discussed.

Antigens, Differentiation, T-Lymphocyte↗