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Biomedical subjects

B Matthews

Publications and source records attributed to B Matthews.

At least 91 records · Page 5Linked to original sources
PubMed1980

The course of post-ganglionic sympathetic fibres distributed with the trigeminal nerve in the cat.

1. The course of post-ganglionic sympathetic fibres to the jaws, face and eye was investigated in cats by observing the effects of nerve sections on responses evoked by stimulation of the cervical sympathetic trunk. 2. Sympathetic fibres were present in the infraorbital and inferior alveolar nerves. From the superior cervical ganglion, all of these fibres travelled in the internal carotid nerve and all but a few passed through the foramen lacerum and joined the trigeminal nerve at its ganglion. 3. Compound action potentials were recorded from sympathetic fibres in six out of twenty-seven teeth. These fibres followed the route described above. 4. Sympathetic fibres to the pupil and levator palpebrae superioris passed from the internal carotid nerve to the eye via the foramen lacerum and the superior orbital fissure. Some fibres causing piloerection in front of the ear travelled by the same route and some travelled with the maxillary division of the trigeminal nerve. 5. Sympathetic fibres to the nictitating membrane followed a similar route to those supplying the pupil except that they entered the cranial vault through the pterygoid foramen. 6. The secretomotor fibres to the submandibular salivary gland and some vasoconstrictor fibres to the lip did not travel with the internal carotid nerve or major branches of the trigeminal nerve.

Action Potentials↗
PubMed1980

Setting up terminal care units.

FROM MY EXPERIENCE THE MAIN PROBLEMS FOUND BY DEVELOPING TERMINAL CARE UNITS HAVE BEEN: initial acceptance from existing medical disciplines; communication difficulties and misunderstandings because of them; mistakes in planning and design, possibly due to lack of experience or attention to detail; occasionally, the appointment of staff that have proved unsuitable; problems in the siting of a unit, usually due to shortage of available land. The ideal site is centrally placed in the community it serves and easily accessible to public transport.

Hospices↗
PubMed1978

Do primary afferents from tooth-pulp cross the midline?

Compound action potentials were recorded from the pulps of canine teeth in cats during stimulation of the inferior dental nerve, trigeminal ganglion or brain stem on one side. Recordings were also made from the inferior dental nerve while stimulating the canine pulps. No evidence for pulpal fibres crossing the midline was found.

Afferent Pathways↗
PubMed1978

Transient kinetics of nicotinamide-adenine dinucleotide phosphate-linked isocitrate dehydrogenase from bovine heart mitochondria.

Pre-steady-state studies of the isocitrate dehydrogenase reaction show that the rate constant for the hydride-transfer step is above 990s-1, and that both subunits of the enzyme are simulataneously active. After the fast formation of NADPH in amounts equivalent to the enzyme subunit concentration, the rate of NADPH formation is equal to the steady-state rate if the enzyme has been preincubated with isocitrate and Mg2+. If the enzyme has been preincubated with NADP+ and Mg2+, in 0.05 M-triethanolamine chloride buffer, pH 7.0, with the addition of 0.1 M-NaCl, the amount of NADPH formed in the fast phase is only 60% of the enzyme subunit concentration, and the turnover rate is at first lower than the steady-state rate. In 0.05 M-triethanolamine chloride buffer, pH 7.0, if the enzyme is preincubated with NADP+ or NADPH, the turnover rate increases 3-fold to reach the steady-state rate after about 5 s. Preincubation of the enzyme with isocitrate and Mg2+ abolishes this lag phase, the steady-state rate being reached at once. It is suggested that the enzyme exists in at least two conformational forms with different activities, and that the lag phase represents the transition (k = 0.4s-1) from a form with low activity to the fully active enzyme, induced by the binding of isocitrate and Mg2+.

Animals↗
PubMed1978

Branched afferent nerves supplying tooth-pulp in the cat.

1. Recordings have been made from nerve terminals in canine and third incisor teeth of cats. 2. Ninety-three tooth-pulp units in ten cats could be excited either by mechanical or electrical stimulation of adjacent mucous membrane or by electrical stimulation of the pulp of a nearby tooth. 3. Section of the trigeminal nerve centrally did not abolish these responses. 4. Results for twelve out of thirteen units tested with collision techniques indicated that the nerves were branched.

Action Potentials↗
PubMed1977

Responses of intradental nerves to electrical and thermal stimulation of teeth in dogs.

1. Experiments were carried out to investigate the mechanism whereby thermal stimul excite nerves to produce pain from teeth. 2. Recordings have been made from single fibres dissected from the inferior dental nerve in dogs during thermal stimulation of the lower canine tooth. 3. In preliminary experiments, no units were found with thresholds close to the thresholds for pain in man (45 and 27 degrees C) and subsequently test stimuli of 55 degrees C, applied for up to 15 sec, and 0-5 degrees C were used. 4. Of 117 fibres tested, forty-three responded to cooling but not to heating and nine responded to heating but not to cooling. 5. By applying thermal stimuli direct to the saphenous nerve in cats, it was shown that these responses might have been due to direct excitation of nerves and not to stimulation of specialized receptors. 6. Some units responded to electrical stimulation of the tooth pulp with a latency which decreased abruptly at a critical intensity as the stimulus was increased above threshold. Evidence was obtained which suggested that this was due to branching of the fibres.

Action Potentials↗
PubMed1976

Sensory and reflex responses to tooth pulp stimulation in man.

Experiments have been carried out to investigate whether all tooth pulp afferent nerves are capable of producing pain. Monopolar and bipolar stimuli were applied to teeth in human subjects and sensory thresholds determined. EMGs were recorded from the masseter and the anterior digastric muscles. With stimuli up to three times the sensory threshold, no response could be detected in the digastric but at, or just above, the sensory threshold, inhibitory effects were produced in masseter muscle. The latency of the muscle response with bipolar stimulation was 18-22 msec. There was no evidence of stimulus spread to nerves outside the teeth. Bipolar and monopolar stimulation both produced the same sensation but this was not described as painful. It is concluded that some pulpal afferent nerves may not be capable of producing pain, and that the sensory and reflex responses at threshold were probably produced by the same fibres.

Adult↗