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Biomedical subjects

A Johnson

Publications and source records attributed to A Johnson.

At least 397 records · Page 22Linked to original sources
PubMed1991

Rebreathing during oxygen treatment with face mask. The effect of oxygen flow rates on ventilation.

The influence of different oxygen flow rates on ventilation and arterial blood gases was investigated in ten healthy volunteers during oxygen treatment with the Hudson mask. Respiratory parameters were calculated using inductive plethysmography calibrated against pneumotachography. The minute ventilation was greater when using the mask with oxygen flow rates less than 5 l/min compared to when no mask was used. With an oxygen flow rate of 3 l/min, minute ventilation was about 140% of minute ventilation without face mask. With 0 l/min, minute ventilation increased to about 160%. The increase in minute ventilation was mainly due to an increase in tidal volume. No change was seen, however, in PaCO2 with different oxygen flow rates. Secondary objective signs following an increase in respiratory work (changes in heart rate, systolic blood pressure and oxygen saturation) were not seen. We recommend 5 l/min as the lowest oxygen flow rate to be used during oxygen therapy with the Hudson mask, in order to avoid rebreathing and excessive respiratory work.

Adult↗
PubMed1991

Hypertriglyceridaemia and its influence on low density lipoprotein regulation of cellular cholesterol synthesis: a comparison between hypertriglyceridaemic diabetic and non-diabetic patients.

The present investigation was undertaken to examine the relationship between serum triglyceride and composition of lipoprotein. Six groups of patients were examined, three with Type 2 (non-insulin-dependent) diabetes and three without diabetes. The groups were further categorized on the basis of their serum cholesterol and triglyceride levels into normocholesterolaemic (serum cholesterol less than 6.5 mmol l-1) and hypercholesterolaemic (serum cholesterol greater than 6.5 mmol l-1) with and without hypertriglyceridaemia (serum triglyceride greater than or less than 3.5 mmol l-1). Low density lipoprotein (LDL) composition was determined and regulation of cholesterol synthesis by LDL was assessed by measuring its effect on [14C]-acetate incorporation into mononuclear leucocyte cholesterol. LDL from the hypercholesterolaemic diabetic patients had a significantly higher esterified cholesterol content when the patients were normotriglyceridaemic (1.14 +/- 0.04 vs 0.76 +/- 0.04 g g-1; p less than 0.01). The ability of LDL to suppress cholesterol synthesis (percent inhibition) was significantly less using LDL from the normocholesterolaemic diabetic patients or hypercholesterolaemic non-diabetic or diabetic patients compared with LDL from the normocholesterolaemic non-diabetic control subjects (47.4 +/- 3.9%, 39.1 +/- 5.1% and 35.2 +/- 4.1% vs 59.5 +/- 1.2%, p less than 0.01). However, hypertriglyceridaemia had no effect on LDL suppression of cholesterol synthesis. We conclude that hypertriglyceridaemia alters LDL composition but the alteration is not associated with the ability of LDL to regulate cholesterol synthesis.

Acetates↗
PubMed1991

Ocular defects in infants of extremely low birth weight and low gestational age.

The eyes of 49 babies who weighed less than 1,000 g at birth or who were born at or before 28 weeks gestation were examined at the age of 4 years. Twenty-one children were normal. The remaining 29 children (59%) had ocular abnormalities which ranged from mild amblyopia to blindness from retinopathy of prematurity. The need to examine children at risk is stressed.

Amblyopia↗
PubMed1991

Tumor necrosis factor-alpha primes pulmonary hemodynamic response to N-formyl-L-methionyl-L-leucyl-L-phenylalanine.

We tested the hypothesis that tumor necrosis factor-alpha (TNF-alpha) primes the hemodynamic response to the neutrophil agonist N-formyl-L-methionyl-L-leucyl-L-phenylalanine (FMLP) in lungs isolated from guinea pigs. Lungs were isolated from animals 18 h after injection of TNF-alpha (3.20 x 10(5) U/kg ip). The infusion of FMLP (300 nM) into lungs isolated after the intraperitoneal administration of TNF-alpha resulted in increases in lung weight, lung (wet-dry)-to-dry weight ratio [(wet-dry)/dry wt], pulmonary capillary pressure, lung myeloperoxidase activity and perfusate thromboxane (Tx)B2 levels. Animals pretreated with the maximal possible amount of endotoxin in the TNF-alpha (1.7 pg endotoxin) did not respond to FMLP. WEB-2086 (37 microM), a platelet-activating factor (PAF) receptor antagonist, added to the perfusate attenuated the hemodynamic and TxA2 response to FMLP. Dazoxiben (0.5 mM), a TxA2 synthetase inhibitor, prevented the FMLP effect. Polyethylene glycol (PEG)-catalase (500 U/ml) added to the perfusate did not affect the FMLP response; however, PEG-catalase (10(5) U/kg) given intraperitoneally with the TNF-alpha decreased the synergism induced by TNF-alpha with FMLP. The data suggest that TNF-alpha primes the lung to the effects of FMLP by increasing the population of resident neutrophils in the lung and/or by in vivo oxidant generation. The pulmonary hemodynamic response and lung edema induced by FMLP are mediated by PAF and TxA2.

Animals↗
PubMed1991

Dextran sulfate inhibits PMN-dependent hydrostatic pulmonary edema induced by tumor necrosis factor.

We tested the hypothesis that neutrophil sequestration is required for the development of tumor necrosis factor- (TNF) induced neutrophil- (PMN) dependent pulmonary edema. TNF (3.2 X 10(5) U/kg ip) was injected into guinea pigs 18 h before lung isolation. After isolation, the lung was perfused with a phosphate-buffered Ringer solution. Dextran sulfate (mol wt 500,000) prevented the changes in pulmonary capillary pressure (Ppc; 8.5 +/- 0.8 vs. 12.8 +/- 0.8 cmH2O), lung weight gain (dW; +0.240 +/- 0.135 vs. +1.951 +/- 0.311 g), and pulmonary edema formation or wet-to-dry wt ratio [(W - D)/D; 6.6 +/- 0.2 vs. 8.3 +/- 0.5] at 60 min induced by PMN infusion into a TNF-pretreated lung. The unsulfated form of dextran had no protective effect [Ppc, dW, and (W - D)/D at 60 min: 11.9 +/- 0.9 cmH2O, +1.650 +/- 0.255 g, and 7.3 +/- 0.2, respectively], whereas the use of another anionic compound, heparin, inhibited the TNF + PMN response [Ppc, dW, and (W - D)/D at 60 min: 5.6 +/- 0.4 cmH2O, +0.168 +/- 0.0.052 g, and 6.4 +/- 0.2, respectively]. Isolated lungs showed increased PMN myeloperoxidase (MPO) activity compared with control in TNF-treated lungs at baseline and 60 min after PMN infusion. Dextran sulfate, dextran, and heparin inhibited the increase in MPO activity. The data indicate that inhibition of PMN sequestration alone is not sufficient for the inhibition of PMN-mediated TNF-induced hydrostatic pulmonary edema and that a charge-dependent mechanism mediates the protective effect of dextran sulfate.

Animals↗
PubMed1991

Viral haemorrhagic fever in Sweden: experiences from management of a case.

The first recognized case in Scandinavia with potential man to man transmission of viral haemorrhagic fever occurred in Linköping, Sweden, in January 1990. Following a visit to Kenya a 21-year-old male student suffered a very severe illness including extremely prolonged high grade fever, rash, disseminated intravascular coagulation with thrombocytopenia and severe bleedings. This necessitated one month of intensive care support including respirator treatment. The patient was discharged after 2 1/2 months in good condition, with a partial femoral nerve paresis. About 100 medical personnel were exposed to aerosol or blood before a strict containment regimen was established. No secondary cases occurred.

Adult↗
PubMed1991

Patterns of outpatient prescription drug use among Pennsylvania elderly.

The Pennsylvania Pharmaceutical Assistance Contract for the Elderly (PACE) provides outpatient prescription drug coverage for nearly one-half million State residents 65 years of age or over with income under $15,000 per year. A description of the PACE program is provided herein, along with data and multivariate results relating to the demographic characteristics of PACE beneficiaries, duration of enrollments, drug utilization and expenditure rates, average prices for covered prescriptions, and drug expense distributions.

Aged↗
PubMed1991

Steady-state cystatin mRNA levels in chicken tissues in response to estrogen.

A full length cDNA clone coding for the cysteine proteinase inhibitor, chicken cystatin, was used to hybridize to RNA extracted from various tissues of the hen during several well defined stages of the 25 h ovulatory cycle. Measurements were made immediately after egg-laying (ovulation), 6 h prior to ovulation (estrogen surge), and 16 h prior to ovulation (minimum estrogen levels). Cystatin was expressed in all tissues examined, being most abundant in lung, followed by brain, heart, oviduct, pectoral muscle, and liver in decreasing order. There were no significant differences in the cystatin mRNA levels at the three different time points for any of the tissues examined, and no differences in the 0.95 kb size of the message. Pharmacological doses of estradiol administered to immature female chickens decreased the steady-state cystatin mRNA levels as analyzed by Northern blots. There were no differences in the pattern of expression in the different tissues between rooster and hens. Our data suggest that estrogen has no direct effect on the regulation of cystatin expression in chicken tissues.

Animals↗
PubMed1991

Variations in bridge construction in commercial laboratories.

Identical working models for the construction of a porcelain bonded to metal three unit fixed bridge were sent to 30 different commercial dental laboratories in the United Kingdom. The material was sent from general dental practice addresses with the implication for treatment under the National Health Service. Each bridge on its return was examined for acceptability using subjective criteria based on clinical and technical factors. There was a wide variation between bridges which gave cause for concern. Lack of a satisfactory prescription for the laboratories to work to must have played a part in this variation. However, it is stressed that the prescription used in this work was deliberately chosen as representative of that which may be used by clinicians.

Color↗
PubMed1991

The microsperm penetration assay: development of a sperm penetration assay suitable for oligospermic males.

OBJECTIVE: To develop a specialized sperm penetration assay (SPA) for the evaluation of sperm from oligospermic patients. DESIGN: The development of the assay is in four parts: determine optimal sperm number; demonstrate quality control; establish statistical limits for fertile population; compare results to in vitro fertilization (IVF) outcome. SETTING AND PATIENTS: A group of 63 patients with oligospermia and/or poor motility and a group of 17 fertile donors were compared using the optimized SPA and the micro-SPA. Sperm from a third group of 35 patients were simultaneously incubated with human ova (IVF) and hamster ova (micro-SPA). MAIN OUTCOME MEASURES: Both types of SPA scores are expressed as a sperm capacitation index (penetrations per ovum). Outcome of IVF is expressed as a percent of ova fertilized. RESULTS: Using 25,000 sperm was found to be optimal. The normal fertile range was statistically determined to have a lower limit (-2 SD) of 2.0 penetrations per ovum. When scores from 63 male factor patients were compared using the optimized SPA, only 43% had sufficient swim-up sperm. However, the micro-SPA could accurately test 100% of the samples because it requires only one tenth the number of sperm. CONCLUSION: The micro-SPA provides a valuable diagnostic test for the evaluation of the male factor patient.

Animals↗
PubMed1991

Responding to parental concerns at the six-month stage.

Health visitors who are able to respond to parental worries about their babies' specific ailments and problems may be providing a more useful service than those who focus on routine assessment of growth and development, write Frances Sherratt, Ann Johnson and Sheila Holmes. Better understanding of the particular concerns of parents of both high and low risk infants could allow more appropriate targeting of resources and improved health care planning.

Adult↗
PubMed1990

The renin-angiotensin-aldosterone system and autosomal dominant polycystic kidney disease.

BACKGROUND: A high incidence of hypertension (50 to 75 percent) occurs early in the course of autosomal dominant polycystic kidney disease. Cyst enlargement, causing bilateral renal ischemia and subsequent release of renin, is proposed as the cause of this form of hypertension. METHODS: To investigate this hypothesis, we measured plasma renin activity and aldosterone concentrations during short-term and long-term converting-enzyme inhibition in 14 patients with hypertension due to polycystic kidney disease, 9 patients with essential hypertension, 11 normotensive patients with polycystic kidney disease, and 13 normal subjects. The groups were comparable with respect to age, sex, body-surface area, degree of hypertension, sodium excretion, and renal function. RESULTS: During the short-term study, the mean (+/- SE) plasma renin activity was significantly higher in the hypertensive patients with polycystic kidney disease than in the patients with essential hypertension, in the supine (0.36 +/- 0.06 vs. 0.22 +/- 0.06 ng per liter.second, P = 0.05) and upright positions (1.03 +/- 0.14 vs. 0.61 +/- 0.08 ng per liter.second, P less than 0.03) and after converting-enzyme inhibition (1.97 +/- 0.28 vs. 0.67 +/- 0.17 ng per liter.second, P less than 0.0006). The mean arterial pressures measured in the supine and upright positions and the plasma aldosterone concentrations measured in the upright position were significantly higher in the normotensive patients with polycystic kidney disease than in the normal subjects. After six weeks of converting-enzyme inhibition, renal plasma flow increased (P less than 0.005), and both renal vascular resistance (P less than 0.007) and the filtration fraction (P less than 0.02) decreased significantly in the hypertensive patients with polycystic kidney disease but not in the patients with essential hypertension. CONCLUSIONS: The renin-angiotensin-aldosterone system is stimulated significantly more in hypertensive patients with polycystic kidney disease than in comparable patients with essential hypertension. The increased renin release, perhaps due to renal ischemia caused by cyst expansion, probably contributes to the early development of hypertension in polycystic kidney disease.

Adult↗
PubMed1990

Functional characterization of two stromal cell lines that support B lymphopoiesis.

Bone marrow stromal cells have well documented effects on the production of B lymphocytes, but whether or not stromal cell signals are involved in the pre-B to B cell transition is unclear. The potential of two stromal cell lines, S10 and S17, in this process was examined. Initial experiments, using a short term liquid culture, indicated that S10 and S17 stroma efficiently supported the generation of clonable B cells (B lymphocyte CFU) from their immediate precursors in fresh bone marrow. The contribution of macrophages and other accessory cells in those experiments was minimized through use of a colony assay system that permits the direct effects of stromal cell signals on single B cell progenitors to be evaluated. The results indicated that soluble mediators from the S10 and S17 lines could support colony formation from fresh or cultured surface Ig- bone marrow cells. Colonies supported by S17 stroma appeared on day 15 and contained cells that expressed the B220 Ag; surface IgM expression was never observed. S10 supported colonies appeared on day 7 and routinely included surface IgM+ cells. Individual colonies were capable of undergoing additional growth when picked and replated directly onto the different stroma. Those colonies replated onto S10 stroma generated surface IgM expressing cells in up to 60% of experiments, but colonies transferred onto the S17 cell line included B cells only 10% of the time. These data demonstrate that stromal cells alone can provide the signals necessary for generating a surface IgM+ B cell from precursors but that not all stromal cell lines are equally efficient at doing so.

Animals↗