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Biomedical subjects

A Mier

Publications and source records attributed to A Mier.

29 records · Page 2Linked to original sources
PubMed1987

Phrenic nerve stimulation in normal subjects and in patients with diaphragmatic weakness.

Phrenic nerve stimulation is often considered to be difficult and unreliable. The time taken for the phrenic nerves to be located and adequately stimulated was measured in 110 subjects, aged 21-89 years, 26 of whom had diaphragmatic weakness; and phrenic nerve conduction time was recorded in 76 of these individuals. Each phrenic nerve was stimulated transcutaneously in the neck with square wave impulses 0.1 ms in duration at 1 Hz and 80-160 volts while diaphragmatic muscle action potentials were recorded with surface electrodes. The time taken to locate either phrenic nerve ranged from two seconds to 22 minutes (median 10s). Both nerves were located in 83 of the 84 control subjects (99%) and in 21 of the 26 patients with diaphragmatic weakness (81%). Mean (SD) phrenic nerve conduction time in the control subjects was 6.94 (0.77) ms on the right and 6.61 (0.77) ms on the left. A weak relationship was found between conduction time and the subjects' age and height. Four out of 24 patients with diaphragmatic weakness had a prolonged phrenic nerve conduction time. Transcutaneous stimulation of the phrenic nerves was not a time consuming procedure, and it was well tolerated, reproducible, and successful in 95% of subjects.

Adult↗
PubMed1987

Platelet function in patients admitted with a diagnosis of myocardial infarction.

Platelet function and thromboxane A2 release were measured in 71 patients admitted to a coronary care unit with a provisional diagnosis of acute myocardial infarction (AMI). All measurements were carried out within twenty-four hours of admission. Of these, 35 patients had the diagnosis of AMI confirmed. The remainder (n = 36), who did not have AMI (NMI), were divided into two groups: those (n = 18) with an unequivocal history of previous vascular disease and those without vascular disease (n = 18). Platelet aggregation and thromboxane A2 (TXA2) release were significantly increased in the AMI group when compared with those in the NMI without vascular disease group or a healthy control group with similar age and sex distribution. Aggregation and TXA2 release in the NMI patients with vascular disease were greater than those in controls and did not differ significantly from those in the AMI group. Patients in the AMI or NMI with vascular disease groups who were taking beta-blockers or calcium channel antagonists at the time of admission showed significantly less platelet aggregation than those who were not taking these drugs. Heparin, added in vitro at therapeutic concentrations, induced significantly more aggregation in patients in the AMI and NMI with vascular disease groups than in the NMI without vascular disease group. We conclude that: platelets obtained from patients with AMI are hyperaggregable and release more TXA2; platelets from patients with significant vascular disease are hyperaggregable, even in the absence of AMI, although they are not as hyperaggregable as those from AMI; treatment with nifedipine and beta-blockers protects these patients from platelet hyperaggregability; heparin induces significant aggregation of platelets from patients with AMI and NMI with vascular disease. These observations are of importance in considering the pathogenesis and treatment of AMI and ischemic heart disease.

Adrenergic beta-Antagonists↗
PubMed1985

Ascites in systemic lupus erythematosus.

Peritoneal serositis is not a widely recognised aspect of systemic lupus erythematosus (SLE). Indeed, ascites in SLE is said to occur only when complicated by the nephrotic syndrome, congestive cardiac failure, or hepatic cirrhosis. We describe two patients who developed ascites that could be attributed to none of these complications.

Adult↗
PubMed1985

Action of abdominal muscles on rib cage in humans.

To assess the actions of the rectus abdominis and external oblique muscles on the rib cage in humans, these two muscles were stimulated with surface electrodes in four normal supine subjects at functional residual capacity. Changes in anteroposterior and transverse rib cage diameters and changes in xiphipubic distance were measured with pairs of magnetometers. Stimulation of rectus abdominis produced a marked decrease in the xiphipubic distance and in the anteroposterior diameter, thus making the rib cage more elliptic. In contrast, stimulation of the external oblique caused a decrease in the transverse diameter, making the rib cage more cylindrical. When both muscles were stimulated simultaneously, the resultant rib cage distortion depended on the relative voltage at which each muscle was stimulated. Electromyogram recordings showed that there was no cross contamination or activity of the diaphragm during the muscle stimulations. Transdiaphragmatic pressure increased with the voltage of stimulation, suggesting passive lengthening of the diaphragm. X-ray studies were performed in two subjects and confirmed the main magnetometer findings. These studies thus confirm that the rib cage in humans is more easily distortable than conventionally thought. The abdominal muscles can distort it in either direction depending on which muscles are contracting.

Abdominal Muscles↗
PubMed1985

Aprotinin induced lipohypertrophy and glomerulonephritis in an insulin dependent diabetic.

In an insulin dependent diabetic who was hyperglycaemic and ketotic despite 3,000 u of insulin injected subcutaneously in 2 divided doses daily, 50 u of intravenous insulin infused over 24 hr restored normal glucose homeostasis. A combination of insulin (800 u) and aprotinin (10,000 u) given twice daily also produced adequate glucose homeostasis for a period of 12 months. The patient then developed local hypertrophy of subcutaneous tissue at the injection site and her diabetic control deteriorated. Non-selective proteinuria followed and she developed nephrotic syndrome. Renal biopsy revealed a membraneous glomerulonephritis with subepithelial immune complexes, appearances consistent with a drug-induced glomerulonephritis. Withdrawal of aprotinin led to a gradual remission of nephrotic syndrome and proteinuria over several months. During this period, her diabetes was well controlled with continuous subcutaneous infusion of insulin at a dose of 500 u/24 hr. This case report demonstrates: the effective use of aprotinin for prolonged periods in insulin dependent diabetics with abnormal absorption of subcutaneously injected insulin; aprotinin induced lipohypertrophy which was not observed when insulin was injected alone; aprotinin-associated glomerulonephritis and nephrotic syndrome; the effective use of CSII--at higher insulin doses--in such patients with subcutaneous malabsorption of insulin.

Adipose Tissue↗
PubMedDate not supplied

Influence of lung volume and rib cage configuration on transdiaphragmatic pressure during phrenic nerve stimulation in man.

Transdiaphragmatic pressure was recorded during bilateral supramaximal percutaneous phrenic nerve stimulation at 1 Hz (twitch Pdi) to investigate the effect of lung volume and rib cage configuration on diaphragm contractility in man. Stimulations were performed in 5 normal supine subjects at resting end expiration (FRC) and at lung volumes above and below FRC, during relaxation against a closed airway and during isovolume manoeuvres. Twitch Pdi at FRC was 24.4 cm H2O. At lung volumes above FRC, twitch Pdi decreased by 7.04 +/- 3.2 cm H2O per litre of volume change. At lung volumes below FRC, twitch Pdi increased by 12.4 +/- 8.6 cm H2O per litre of volume change. When the diaphragm was lengthened during an isovolume manoeuvre at FRC, twitch Pdi increased. A similar relationship between lung volume and twitch Pdi was obtained during stimulations performed with abdominal binding. These results demonstrate that the pressure developed by the diaphragm during phrenic nerve stimulation is significantly affected both by increases and decreases in lung volume and by the rib cage configuration at which stimulation is performed.

Adult↗
PubMedDate not supplied

Diarrhea and metformin in a diabetic clinic.

In a questionnaire-based survey of 285 randomly selected diabetic patients, diarrhea was found to occur in 8%; this was found to be similar to that in 150 nondiabetic control patients attending other medical clinics (8%). When the diabetic patients were divided into separate therapeutic groups, metformin-treated (with or without sulfonylureas) patients had a markedly greater prevalence of diarrhea (20%) than those not on this drug (6%). A majority of patients with metformin-associated diarrhea had soiling of clothes as a problem, while at least two complained of frank loss of control over their anal sphincter. These patients did not have autonomic neuropathy, and in all who stopped this drug, diarrhea settled within 2-5 days. Only 6% of insulin-dependent diabetic individuals (IDD) had diarrhea, one of whom had explosive nocturnal stools with incontinence and features diagnostic of autonomic neuropathy. Metformin is by far the commonest cause of diarrhea and incontinence in our diabetic clinic, where it is used routinely. In contrast, diarrhea due to autonomic neuropathy is rare.

Diabetes Mellitus, Type 1↗