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Biomedical subjects

C Bell

Publications and source records attributed to C Bell.

At least 343 records · Page 19Linked to original sources
PubMed1967

The localization of acetylcholinesterase at the autonomic neuromuscular junction.

Acetylcholinesterase has been localized at the autonomic neuromuscular junction in the bladder of the toad (Bufo marinus) by the Karnovsky method. High levels of enzyme activity have been demonstrated in association with the membranes of cholinergic axons and the adjacent membranes of the accompanying Schwann cells. The synaptic vesicles stained in occasional cholinergic axons. After longer incubation times, the membrane of smooth muscle cells close to cholinergic axons also stained. Axons with only moderate acetylcholinesterase activity or with no activity at all were seen in the same bundles as cholinergic axons, but identification of the transmitter in these axons was not possible.

Acetylcholinesterase↗
PubMed1967

An electrophysiological study of the effects of atropine and physostigmine on transmission to the guinea-pig vas deferens.

1. The effects of physostigmine and atropine on transmission to the longitudinal musculature of in vitro preparations of the guinea-pig vas deferens have been examined using intracellular micro-electrodes.2. Atropine (5 x 10(-7) to 10(-6) g/ml.) increased the rate of decay of excitatory junction potentials (EJPs) in response to post-ganglionic stimulation.3. Physostigmine (5 x 10(-6) g/ml.) reduced the mean resting potential of the muscle cells from -60.5 to -51.5 mV and lowered the voltage of post-ganglionic stimulation necessary for initiation of an action potential in the muscle. In some but not all of the cells studied the time course of the EJP was markedly prolonged.4. At concentrations which did not alter the response to post-ganglionic stimulation (5 x 10(-7) to 10(-6) g/ml.), physostigmine caused fully facilitated EJPs to appear with the first pulse of a preganglionic train of stimulation.5. Atropine antagonized all the above effects of physostigmine.6. Physostigmine (5 x 10(-7) to 10(-6) g/ml.) also lowered the voltage of preganglionic stimulation necessary for initiation of an action potential in the muscle. This effect was not antagonized by atropine.7. The results are interpreted as being evidence for the existence of separate cholinergic and adrenergic motor fibres to the musculature of the guinea-pig vas deferens.

Journal Article↗
PubMedDate not supplied

Antibodies to DNA in patients with rheumatoid arthritis and juvenile rheumatoid arthritis.

Antibodies to double-stranded DNA (DSDNA) were found in 18 patients with RA, in 5 patients with JRA, and in 5 patients with undiagnosed connective tissue disease. Five patients had clinical features consistent with both RA and SLE, 11 with only RA, and 5 with only JRA. Based on these observations, the presence of serum anti-DSDNA antibodies should not be used as a sole criterion in the diagnosis of SLE.

Antibodies↗
PubMedDate not supplied

Blood lipid effects of antihypertensive therapy: a double-blind comparison of the effects of methyldopa and propranolol.

Thirty-two middle-aged men with essential hypertension completed a double-blind randomly allocated comparison of the effects of methyldopa versus propranolol on blood lipid levels. After a four-week period on a placebo for each drug, subjects were titrated for the next six weeks with either methyldopa from 500 to 2000 mg/day or propranolol from 80 to 320 mg/day plus a placebo for the other drug until supine diastolic blood pressure was below 90 mm Hg or the ceiling dose was reached. Subjects were then maintained on the achieved drug dose for an additional six weeks and finally switched back to a placebo for each drug for four more weeks. Blood lipid levels were measured twice during each study period and the values averaged and compared. Neither drug significantly affected levels of total plasma cholesterol. However, both drugs reduced high-density lipoprotein (HDL) cholesterol levels about 10 per cent and increased the total cholesterol to HDL cholesterol ratio. In addition, propranolol significantly increased plasma triglyceride levels (28.3 per cent). The changes in lipid levels were not dose related. Whether or not these blood lipid changes persist and their possible clinical implication during prolonged therapy remain to be elucidated.

Aged↗
PubMedDate not supplied

Prenatal screening for illegal drugs. Dilemma for the nurse-midwife.

Prenatal screening for illegal drugs poses very complex ethical problems for the nurse-midwife who must make the decision whether to screen for illegal drugs and whether to report positive results to state child abuse investigators. We argue that the results of prenatal screening for illegal drug use should not be used for determination of child abuse and that the nurse-midwife should not be required to report the results of these screens for illegal drugs to state child protection agencies. It is far from clear that required reporting offers any benefit to the fetus or future child, and there are serious ramifications of reporting for the fetus, the pregnant woman, and the nurse-midwifery profession. However, we do argue that prenatal screening for both illegal and legal drug use should be encouraged and should be done as early as possible in the pregnancy. Prenatal screening for drugs should only be used by the nurse-midwife as a diagnostic procedure wherein standard informed consent and confidentiality restraints are maintained.

Child Abuse↗
PubMedDate not supplied

Vasodilator neurons supplying skin and skeletal muscle of the limbs.

Three types of neural vasodilator responses can be identified in the vascular beds of limbs. The first is almost certainly cholinergic, is restricted to precapillary resistance vessels in skeletal muscle, and appears to be activated during emotionally-oriented arousal. The second is non-cholinergic, is attenuated by histamine H1-receptor antagonists, and occurs in both skeletal muscle and skin. This response may also be evoked by emotional stimuli. The third response is localized to arteriovenous shunts in the digits, and is generally insensitive to both anticholinergic and antihistaminic drugs. It is probably implicated in thermoregulatory control, and may mediate cold vasodilation.

Adrenergic Fibers↗