Search PubMed⌕ Search

Biomedical subjects

A Hay

Publications and source records attributed to A Hay.

At least 55 records · Page 3Linked to original sources
PubMed1993

Gastric intramural pH as a predictor of success or failure in weaning patients from mechanical ventilation.

OBJECTIVE: To determine whether gastric intramural pH (pHi), an indirect measure of gastric mucosal ischemia, can be used to predict the success of weaning from mechanical ventilation. Gastric mucosal ischemia (and, therefore, acidosis) may develop in patients during unsuccessful attempts to wean them from mechanical ventilation because blood flow from nonvital areas (for example, splanchnic bed) is diverted to meet the increased demands of respiratory muscles. DESIGN: Cohort study. SETTING: Intensive care unit. PATIENTS: Twenty-nine patients receiving assisted mechanical ventilation for respiratory failure who were thought by their physicians to be weanable from mechanical ventilation. MEASUREMENTS: Simultaneous samples of arterial blood and gastric juice were obtained from patients during assisted mechanical ventilation, as well as during weaning trials. The predictor variable, pHi, was calculated using the following equation: 6.1 + log HCO3/(gastric PCO2 x 0.0307). The outcome was success or failure of weaning, decided by physicians blinded to the study. RESULTS: Patients who could not be weaned from mechanical ventilation had a substantially reduced gastric pHi (7.36 during mechanical ventilation compared with 7.09 during weaning [difference, 0.27; 95% Cl, 0.12 to 0.42; P < 0.01]). Patients who were successfully weaned from mechanical ventilation showed no change in pHi (7.45 during mechanical ventilation compared with 7.46 during weaning [difference, 0.01; Cl, -0.01 to 0.03; P = 0.29]). The sensitivity and specificity of pHi in predicting weaning success or failure were both 100% (Cl, 81 to 100 and 72 to 100, respectively). CONCLUSION: Gastrointestinal acidosis may be an early sign of weaning failure. Measurement of pHi, which is simple and rapid, may be of practical value in predicting the likelihood of weaning success or failure during weaning trials.

Acidosis↗
PubMed1993

A comparison of argon and diode photocoagulation combined with supplemental oxygen for the treatment of retinopathy of prematurity.

The efficacy of argon and diode laser photocoagulation of the avascular peripheral retina for threshold retinopathy of prematurity (ROP) was compared in a prospective trial. The study group included 9 premature infants (17 eyes). In each infant, one eye was treated with the diode laser indirect ophthalmoscope (LIO), and the fellow eye was treated with the argon LIO. Supplemental oxygen therapy was administered after laser treatment to all nine infants. The mean duration of the follow-up period was 9.7 +/- 2.6 months. All 17 eyes (100%) had complete regression of ROP and favorable outcomes. The diode and argon LIO appear to be equally effective in treating threshold ROP. Two patients sustained burns of the tunica vasculosa lentis and anterior lens capsule in the argon laser treated eye but not in the fellow diode treated eye. Photocoagulation with either the diode or argon LIO, combined with supplemental oxygen treatment, appears to be a promising treatment for retinopathy of prematurity.

Combined Modality Therapy↗
PubMed1993

Expression of the terminal protein of hepatitis B virus is associated with failure to respond to interferon therapy.

The terminal protein domain of the hepatitis B viral polymerase can inhibit the cellular response to interferon. To clarify the clinical relevance of this inhibitory effect, we examined the expression of terminal protein in liver biopsy specimens from patients with chronic hepatitis B infection. We found that expression of terminal protein is associated with a failure of hepatocytes to respond to interferon, as assessed by expression of the interferon-inducible protein beta 2-microglobulin. Patients whose liver specimens contained large numbers of cells expressing terminal protein tended not to respond to treatment. During interferon therapy the percentage of cells expressing terminal protein remained constant, but treatment significantly reduced the number of cells that expressed the hepatitis B nucleocapsid protein. Hence expression of terminal protein in a cell may prevent elimination of the virus by interferon therapy.

Adult↗
PubMed1992

Scientific discourse, in public.

The experience of writing for a wider audience has benefits and drawbacks. Attempting to make scientific issues more accessible to non-scientists is no easier than explaining them to peers. Indeed, explaining toxicological data such as solvent measurements from a hazardous waste site can be even more difficult, especially in addressing those living next to the site. Alastair Hay reconsiders his experience in two cases that brought toxicology under public scrutiny.

Chemical Industry↗
PubMed1992

Effect of metals on interleukin-6 (IL-6) mitogenic stimulation of murine hybridoma cells.

The effect of several divalent metal cations (Co, Cu, Zn, Hg and Pb) on the proliferative response of B9 hybridoma cells to IL-6 has been investigated. At concentrations which are not cytotoxic all the metals inhibited proliferation. The inhibition by Cd and Pb was dependent on both time of addition of the metal and IL-6 concentration. Cd (10 microM) and Pb (50 microM) added at the same time as IL-6 were inhibitory but added 24h later had no effect. Increasing the concentration of IL-6 overcame the inhibitory effect of Cd (10 microM) and Pb (50 microM). Inhibition caused by the other metals was independent of either time of addition or IL-6 concentration. IL-6 did not stimulate an increased intracellular concentration of metallothionein suggesting that the protective effect of IL-6 is not mediated via induction of metallothionein. The results suggest that there are at least two distinct metal sensitive events in B9 proliferation, i) IL-6 reversible inhibition by Cd and Pb ii) IL-6 independent inhibition by Co, Cu and Hg.

Animals↗
PubMed1991

Toxicity from ragwort and fat cow syndrome, or from industrial chemicals: the value of epidemiological analysis for interpreting clinico-pathological findings.

When livestock in close proximity to industries develop signs of ill-defined disease, toxic effects from industrial pollution should be considered in the differential diagnosis. In establishing the final diagnosis, epidemiological methods should be applied to supplement the clinical and pathological techniques. This viewpoint is illustrated by two case-histories describing episodes of cattle disease in central Scotland. A long-established and successful dairy herd in central Scotland sustained severe morbidity and mortality amongst animals which had grazed on a field beside a recently established dump which contained wastes from a chemical waste incinerator. An official investigation concluded that the episode of disease was the result of ragwort poisoning; this diagnosis was reached on clinical and pathological grounds only. A similarly unexpected and severe epidemic occurred a few years later in another dairy herd, about 1 km further away from that incinerator (which was also within 100 m of a municipal incinerator). The official investigation, which again focused on clinical and pathological criteria, led to the diagnosis of fat cow syndrome. In the first episode, contaminated water drained from the chemical waste dump on to the cows' field; in the second episode, the relevant field was affected by airborne pollution from the two waste incinerators mentioned earlier. In both episodes, the epidemiological features, which were not examined systematically by the original investigators, were consistent with the hypothesis that these episodes resulted from exposures to toxic contaminants.

Animals↗
PubMed1991

A recent assessment of cocoa and pesticides in Brazil: an unhealthy blend for plantation workers.

Cocoa is the major source of income for the Brazilian state of Bahia and some 2.3 million people rely on the crop for their livelihood. Most cocoa is grown on large plantations where working conditions are often extremely poor. Few workers using pesticides on plantations, or on small-holdings, have had instruction about safe working practices. Protective clothing is rarely available. The result is frequent complaints about health. None of this likely to improve in the short term given Brazil's perilous economic situation.

Agricultural Workers' Diseases↗
PubMed1991

Needle penetration of the globe during retrobulbar and peribulbar injections.

The charts of 23 patients with needle penetration of the globe during retrobulbar or peribulbar injections between January 1980 and May 1990 were reviewed. Possible needle penetration risk factors included high myopia, previous scleral buckling procedures, injection by nonophthalmologists, and poor patient cooperation during the injection. Of the 23 cases of ocular penetration, 16 (70%) were from sharp (22-, 23-, and 25-gauge) needles, and 7 (30%) were from blunt (23- and 25-gauge) needles. Management options depended on the severity of the intraocular injury. Retinal breaks without retinal detachment were treated by laser photocoagulation (four cases) or cryopexy (one case) and were observed in three cases. More advanced complications (retinal detachment and vitreous hemorrhage) were usually treated by pars plana vitrectomy with or without a scleral buckle (12 of 14 cases). The final visual acuity was 20/400 or better in only 2 of the 14 retinal detachment cases. In cases without retinal detachment, the final visual acuity was 20/50 or better in 7 of 9 cases.

Adult↗
PubMed1991

Measuring compliance in methadone maintenance patients: use of a pharmacologic indicator to "estimate" methadone plasma levels.

A quantitative indicator of compliance is not available for methadone--the drug of choice for the treatment of opioid addiction. We successfully used low-dose phenobarbital (a valid pharmacologic indicator) to measure compliance by incorporating the drug into the methadone medication of patients attending an addiction unit. Plasma phenobarbital and methadone concentrations were measured in 20 (11 clinic-based and 9 community-based) patients receiving long-term treatment with the phenobarbital level-to-dose ratio, together with interviews, to validate methadone measurements and to monitor compliance. Patients attending the unit on a daily basis and who consumed their medication in the clinic were substantially more compliant than community-based patients. Laboratory measurements of phenobarbital and methadone helped to identify the use of illicit methadone, as well as incorrect self-administration, such as the consumption of several days' dosage at one time.

Adult↗
PubMed1991

High-dose methadone and the need for drug measurements in plasma.

We report a case of high-dose methadone prescribed to a heroin addict for pain control. The patient was prescribed methadone during convalescence from surgery and subsequently for maintenance treatment. Dosing was started at 360 mg of methadone per day and reduced over 12 days to an 80 mg/day maintenance dose. Although the patient was drowsy on the initial dose, his recovery was uneventful. However, there were complaints of pain and withdrawal discomfort when the plasma concentration decreased to less than 1 mg/L. Measurements of methadone in plasma were helpful for monitoring the recovery of this patient after surgery and are likely to prove useful in similar cases.

Adult↗
PubMed1991

Methadone in saliva.

Explore the source record for details and available documents.

Chromatography, High Pressure Liquid↗