Biomedical subjects
Publications and source records attributed to M Griffith.
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Over a 2-year period 192 patients with acute myocardial infarction (AMI) were transported by helicopter and treated with recombinant tissue-plasminogen activator (tPA). All patients were entered into the Thrombolysis in Myocardial Infarction-Phase II (TIMI II) trial. Eighty-two of these patients were treated with tPA after aeromedical transport to a tertiary care center. One hundred ten patients had tPA treatment initiated by the flight crew prior to transport. The flight crews initiated therapy 28 +/- 11 minutes after arrival at the sending hospital. The post-flight treated patients received the tPA bolus 82 +/- 20 minutes after arrival at the sending hospital (P less than .0001), and 41 +/- 18 minutes after arrival at the receiving hospital (P less than .0001). Based on enzyme and electrocardiographic changes, all patients in the study had a confirmed diagnosis of AMI before discharge. Patients with inferior myocardial infarction (MI) treated with tPA in-flight were more likely to suffer from bradycardia and hypotension requiring atropine injection during transport than the post-flight treated patients or in-flight treated patients with anterior MI. There was no in-flight mortality in either group. Our experience indicates that patients with AMI can be transported safely during tPA therapy. Also, a trained team whose sole responsibility is the early evaluation and initiation of therapy in a patient with AMI can function as accurately and significantly more rapidly than tertiary care emergency department and ICU personnel following identical protocols.
OBJECTIVES: To determine whether among people aged 65 and over those who died at advanced old age spent more of their last year of life in hospital than those who died younger, and whether the increase in longevity in the elderly between 1976 and 1985 was accompanied by increased time spent in hospital in the last year of life. DESIGN: Linkage of death records to abstracts of records of hospital inpatient care in the preceding year of patients' lives. SETTING: Six health districts in England covered by the Oxford record linkage study. RESULTS: People who died at advanced ages (85 and over) were less likely than people who died at younger ages (65-84) to have been admitted to hospital in the last year of life. Once admitted the very old tended to spend longer in hospital than others. The mean total time spent in hospital by the elderly in the year before death (based on all deaths including those among people not admitted at all) showed no appreciable change over time. The median time in hospital based on all deaths increased by about three days between 1976 and 1985. During that time there was a gain in life expectancy in the population of about one year from the age of 65. CONCLUSION: The gain in life expectancy in this population was not at the expense of any substantial increase in time spent in hospital in the final year of life.
The effects of intravenous adenosine and intravenous verapamil on paroxysmal junctional tachycardia were compared in 20 patients undergoing invasive cardiac electrophysiologic study. In 13 patients the diagnosis was of a reentrant tachycardia using an extranodal accessory connection (atrioventricular [AV] reentrant tachycardia); 5 of these patients had overt preexcitation in sinus rhythm, 4 had concealed accessory connections and 4 had latent or intermittent preexcitation. In 7 patients the diagnosis was of an AV nodal reentrant tachycardia. Administration of adenosine resulted in termination of tachycardia in all 20 patients at a mean dose of 0.125 mg/kg (range 0.05 to 0.20). Although termination of tachycardia was frequently accompanied by atrial and ventricular premature complexes, no significant arrhythmias were observed after conversion. Administration of verapamil (0.145 mg/kg) resulted in termination of tachycardia in 19 of 20 patients but was followed by symptomatic arrhythmias in 2: preexcited atrial flutter in 1 patient and preexcited atrial tachycardia in another. Latent or intermittent preexcitation was unmasked in 4 of 4 patients immediately after termination of tachycardia by adenosine. Termination of tachycardia by verapamil revealed preexcitation in only 1 of these 4 patients. Analysis of results in terms of successful termination of tachycardia, absence of significant arrhythmias after conversion and unmasking of latent or intermittent preexcitation reveals that adenosine therapy was satisfactory in all 20 patients, whereas verapamil was satisfactory in only 14 of the 20 patients (p less than 0.05). All 6 of the patients with unsatisfactory responses to verapamil had AV reentrant tachycardia. These results suggest that adenosine has particular advantages over verapamil as acute treatment for patients presenting with an AV reentrant tachycardia.
In a randomised cross-over study, six patients with recurrent sustained ventricular tachycardia (VT) were treated with 3 regimens--amiodarone, amiodarone plus metoprolol, and amiodarone plus xamoterol. All patients had poor left ventricular function and were resistant to multiple drugs. Xamoterol (a partial beta-agonist) was more effective than metoprolol as adjuvant therapy to amiodarone in the control of recurrent sustained ventricular arrhythmias and was not associated with any clinical deterioration of ventricular function. Xamoterol was also more effective than metoprolol for suppression of VT at programmed stimulation and as effective as metoprolol for suppression of VT on exercise. Exercise tolerance was significantly greater during treatment with xamoterol/amiodarone than during treatment with metoprolol/amiodarone or with amiodarone alone.
In a double-blind parallel group study, 46 patients with chronic stable angina were randomized, after a 2-week placebo washout period, to 1 of 3 treatment groups for an additional 2 weeks. Groups 1 and 2 received nicorandil (5 mg, n = 5; 10 mg, n = 10) twice daily, respectively, increasing to 10 and 20 mg (n = 20) twice daily after 1 week of treatment; group 3 continued to receive placebo. A symptom-limited Bruce protocol exercise test was performed before and 2 hours after the initial dose and, after 2 weeks of treatment, 2 and 12 hours after administration. The following parameters were measured: resting, peak exercise and recovery blood pressure and heart rate, exercise duration, time to onset of angina and time to 1 mm of ST-segment depression. After initial dosing, there were significant increases in exercise duration (16%--n = 5, n = 10 vs -2% [placebo]) and time to onset of angina (20%, n = 5; 26%, n = 10 vs 5% [placebo]) (p less than 0.05). Time to onset of 1 mm of ST-segment depression increased in the nicorandil-treated groups compared with that in the placebo group (27%, n = 5; 25%, n = 10 vs 8% [placebo]). Calculated total exercise work increased in both nicorandil groups compared with exercise work in the placebo group (30%, n = 5; 19%, n = 10 vs 3% [placebo]). A decrease in resting systolic blood pressure (12%) in the 10-mg group was the only significant alteration in the hemodynamic parameters.(ABSTRACT TRUNCATED AT 250 WORDS)
Infusion of saline in healthy volunteers produced a significant rise in plasma atrial natriuretic peptide, which was accompanied by the urinary excretion of cyclic GMP and sodium. Although the time-course of cyclic GMP excretion almost mirrored that of plasma ANP, that of sodium showed sustained phase, indicating involvement of additional humoral regulators. ANP did not stimulate the excretion of enzymic or immunoreactive tissue kallikrein.
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Data from the Oxford Record Linkage Study were analysed to determine the amount of work undertaken in day case surgery for 12 surgical conditions in five districts in the Oxford Region during the years 1976 to 1985. Record linkage was used to study readmission rates, comparing day surgery with inpatient care. The use of day surgery gradually increased in some conditions (eg, termination of pregnancy, female sterilisation) but did not increase from a fairly low base for others (eg, inguinal hernia repair, operations on varicose veins and haemorrhoids). There were striking differences between the districts in the use of day case care. For example, the use of day case care as a percentage of all hospital admissions for termination of pregnancy varied from 1% in one district to 24% in another; that for dilatation and curettage varied from 1% to 43%; and that for female sterilisation varied from less than 1% to 35%. Emergency readmission rates after day surgery were similar to those following inpatient treatment. We conclude that the use of day surgery for some conditions judged suitable for day care is still low and, even within one region, variation in the use of day surgery is considerable. The reasons for continued reluctance in some places to undertake more day surgery merit investigation.
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Thylakoids isolated from leaves of winter rye (Secale cereale L. cv Puma) grown at either 20 or 5 degrees C were extracted with the nonionic detergents Triton X-100 and octyl glucoside. Less total chlorophyll was extracted from 5 degrees C thylakoids by these detergents under all conditions, including pretreatment with cations. Thylakoids from either 20 or 5 degrees C leaves were solubilized in 0.7% Triton X-100 and centrifuged on sucrose gradients to purify the light harvesting complex (LHCII). Greater yields of LHCII were obtained by cation precipitation of particles derived from 20 degrees C thylakoids than from 5 degrees C thylakoids. When 20 and 5 degrees C thylakoids were phosphorylated and completely solubilized in sodium dodecyl sulfate, no differences were observed in the (32)Pi-labeling characteristics of the membrane polypeptides. However, when phosphorylated thylakoids were extracted with octyl glucoside, extraction of LHCII associated with the 5 degrees C thylakoids was markedly reduced in comparison with the extraction of LHCII from 20 degrees C membranes. Since 20 and 5 degrees C thylakoids exhibited significant differences in the Chl content and Chl a/b ratios of membrane fractions produced after solubilization with either Triton X-100 or octyl glucoside, and since few differences between the proteins of the two membranes could be observed following complete denaturation in sodium dodecyl sulfate, we conclude that the integral structure of the thylakoid membrane is affected during rye leaf development at low temperature.
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Mestome sheath cells of winter rye (Secale cereale L. cv Puma) deposit suberized lamellae in their secondary cell walls. Histochemical tests including acid digestion and staining with Sudan IV and Chelidonium majus root extract were used to detect the presence of suberin in the primary cell wall. There was no evidence of a Casparian band between adjacent mestome sheath cells. Fluorescent dye techniques were used to trace solute movement through the rye leaf apoplast. Calcofluor white M2R, a fluorescent dye which binds to cell walls as it moves apoplastically, proved to be too limited in its mobility in leaves to test mestome sheath permeability. Trisodium 3-hydroxy-5,8,10 pyrene trisulfonate, a fluorescent dye which is mobile in the apoplast, moved easily up the vascular bundles in the transpiration stream, and diffused outward from the veins to the epidermal cell walls within minutes of reaching a particular level in the leaf. We conclude that the suberized mestome sheath of rye leaves is freely permeable to solutes moving apoplastically through radial primary cell walls.
Chloroplasts isolated from rye (Secale cereale L. cv Puma) grown at 5 degrees C (RH) accumulated 260% more plastoquinone A (PQA) per plastid than chloroplasts isolated from rye grown at 20 degrees C (RNH). The number of plastoglobuli increased by 270% in RH chloroplasts compared with RNH plastids. When RH plastids were lysed and washed, the number of plastoglobuli associated with thylakoid membranes decreased significantly, yet the PQA levels remained high. Room temperature fluorescence induction indicated that (a) there is no change in the size of the PQA pool immediately available for photochemistry in RNH and RH thylakoids and (b) there is a pool of oxidized PQA present in RNH and RH thylakoids which is not available for photochemistry. The accumulated PQA in RH thylakoids may reflect an increased nonphotochemical function such as regulation of thylakoid protein phosphorylation or protection against photoinhibition.
Thylakoids isolated from winter rye (Secale cereale L. cv Puma) grown at 20 degrees C (nonhardened rye, RNH) or 5 degrees C (cold-hardened rye, RH) were characterized using chlorophyll (Chl) fluorescence. Low temperature fluorescence emission spectra of RH thylakoids contained emission bands at 680 and 695 nanometers not present in RNH thylakoids which were interpreted as changes in the association of light-harvesting Chl a/b proteins and photosystem II (PSII) reaction centers. RH thylakoids also exhibited a decrease in the emission ratio of 742/685 nanometers relative to RNH thylakoids.Room temperature fluorescence induction revealed that a larger proportion of Chl in RH thylakoids was inactive in transferring energy to PSII reaction centers when compared with RNH thylakoids. Fluorescence induction kinetics at 20 degrees C indicated that RNH and RH thylakoids contained the same proportions of fast (alpha) and slow (beta) components of the biphasic induction curve. In RH thylakoids, however, the rate constant for alpha components increased and the rate constant for beta components decreased relative to RNH thylakoids. Thus, energy was transferred more quickly within a PSII reaction center complex in RH thylakoids. In addition, PSII reaction centers in RH thylakoids were less connected, thus reducing energy transfers between reaction center complexes. We concluded that both PSII reaction centers and light-harvesting Chl a/b proteins had been modified during development of rye chloroplasts at 5 degrees C.
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