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Biomedical subjects

H Blumberg

Publications and source records attributed to H Blumberg.

52 records · Page 3Linked to original sources
PubMed1981

Do dichotomizing afferent fibers exist which supply visceral organs as well as somatic structures? A contribution to the problem or referred pain.

Fibers in the inferior splanchnic nerves were found which could be activated by electrical stimulation of one of the lumbar white rami as well as of the somatic nerve of the same spinal segment at stable latency. The responses of these fibers reliably followed high frequency stimulation (20-100 Hz) of the nerves. The axons were unmyelinated (conduction velocity 1.02 +/- 0.57 m/sec, mean +/- 1 S.D., n = 14), had no ongoing discharges and could not be excited by afferent stimuli via a spinal or supraspinal reflex pathway. Therefore, it is likely that these fibers are afferent. The findings support the hypothesis that referred pain may be produced by dichotomizing sensory fibers, one branch passing to visceral organs and the other branch to the site of reference in muscle or skin.

Afferent Pathways↗
PubMed1980

Baroreceptor and chemoreceptor reflexes in postganglionic neurones supplying skeletal muscle and hairy skin.

Postganglionic neurons supplying skeletal muscle and hairy skin of the cat's hindlimb were investigated for their reactions to stimulation of carotid baroreceptors and chemoreceptors in chloralose-anaesthetized, immobilized and artificially ventilated animals. The baroreceptors were stimulated by the pulsatile blood pressure and by pressure increases applied to an isolated carotid sinus (carotid blind sac) leaving only one intact buffer nerve. Chemoreceptors were stimulated by systemic hypoxia and by intracarotid bolus injections of CO2-saturated saline. The cardiac rhythmicity of activity in the postganglionic neurones (evaluated from the post-R-wave histograms) and the neurone reactions to intracarotid pressure increases were fairly well correlated, with a coefficient of r = 0.84. The time course and magnitude of inhibitory responses to intracarotid pressure increases were identical in some of the cutaneous postganglionic neurones and postganglionic neurones supplying skeletal muscle. The majority of the postganglionic neurones supplying skin, however, exhibited a weaker inhibitory response and a different time course in their activity during and after the sinus pressure increases. Muscle postganglionic neurones were excited and the majority of the cutaneous postganglionic neurones were inhibited by stimulations of arterial chemoreceptors produced by systemic hypoxia and by intracarotid injection of CO2-saturated saline. Small fractions of the post-ganglionic neurones supplying skin were excited by stimulation of arterial chemoreceptors. The activity of these cutaneous postganglionic neurones showed a strong cardiac rhythmicity. It is proposed that those postganglionic neurones supplying skin which are affected by stimulation of baro- and chemoreceptors in the same manner as are the postganglionic neurones supplying skeletal muscle may innervate cutaneous resistance (nutritional) vessels. It is likewise suggested that those cutaneous postganglionic neurones inhibited by stimulation of arterial chemoreceptors and under weak control by the arterial baroreceptors may innervate cutaneous capacitance and shunt vessels.

Animals↗
PubMedDate not supplied

Changes of reflexes in vasoconstrictor neurons supplying the cat hindlimb following chronic nerve lesions: a model for studying mechanisms of reflex sympathetic dystrophy?

The generic term 'reflex sympathetic dystrophy' describes a clinical syndrome which sometimes develops after traumata at the extremities with lesions of nerves or --more rarely--after other events. The syndrome consists of the following components: pain (hyperpathia, allodynia), trophic changes of skin and deep tissues, dysregulation of sweating and cutaneous blood flow of the extremity concerned. It is assumed that all symptoms are produced by abnormal sympathetic activity. Interruption of the sympathetic activity to the affected extremity abolishes most of the pain and may lead to remission of the trophic changes. The hypothesis is that the trauma with lesion of the primary afferent axons leads subsequently to an abnormal state of the primary afferent neurons and to distorted processing of information in the spinal cord. As a consequence of this abnormal central state the activity in the sympathetic (vasomotor and sudomotor) supply to the affected extremity is distorted. The results are pain, trophic changes and dysregulations of autonomic effector organs. In some yet unknown way a vicious circle between periphery and spinal cord is established (afferent leads to spinal cord leads to sympathetic leads to afferent). This hypothesis was the starting point for analysis of the reflex pattern in postganglionic vasoconstrictor neurons supplying the cat hindlimb after chronic nerve lesions performed in the same limb (cutting and ligating a skin nerve; suturing the central stump of a skin nerve to the peripheral stump of a muscle nerve). The results obtained show that the reciprocity of the reflex pattern which is normally observed between cutaneous and muscle vasoconstrictor neurons is lost in many animals. Cutaneous vasoconstrictor neurons are very similar to muscle vasoconstrictor neurons in their reactions to stimulation of arterial baroreceptors and chemoreceptors. If the same sequence of events also occurs in patients with reflex sympathetic dystrophy, it could explain the dysregulation of blood flow through skin and also the occurrence of trophic changes in the limb.

Animals↗
PubMedDate not supplied

Sequence homology of the yeast regulatory protein ADR1 with Xenopus transcription factor TFIIIA.

Classical yeast genetics coupled with the cloning of regulatory genes by complementation of function is a powerful means of identifying and isolating trans-acting regulatory elements. One such regulatory gene is ADR1 which encodes a protein required for transcriptional activation of the glucose-repressible alcohol dehydrogenase (ADH2) gene. We now report the nucleotide sequence of ADR1; it encodes a polypeptide chain of 1,323 amino acids, of which the amino-terminal 302 amino acids are sufficient to stimulate ADH2 transcription. This active amino-terminal region shows amino-acid sequence homology with the repetitive DNA-binding domain of TFIIIA, an RNA polymerase III transcription factor of Xenopus laevis. Similar domains are found in proteins encoded at the Krüppel and Serendipity loci of Drosophila melanogaster. We discuss the implications of this structural homology and suggest that a similar domain may exist in other yeast regulatory proteins such as those encoded by GAL4 (ref. 13) and PPR1 (ref.14).

Amino Acid Sequence↗
PubMedDate not supplied

Two zinc fingers of a yeast regulatory protein shown by genetic evidence to be essential for its function.

The best-understood protein structure involved in DNA binding is the helix-turn-helix motif. A second DNA-binding domain, the finger structure, has been proposed on the basis of sequence analysis, partial proteolysis and zinc content of Xenopus transcription factor TFIIIA. Other eukaryotic proteins were subsequently found to contain contiguous repeat units of the postulated finger motif. Each repeat unit contains thirty amino acids and is thought to bind a zinc atom using two cysteines and two histidines as ligands. The protein loop or finger between apparent zinc ligands is rich in DNA-binding residues and is thought to make specific contacts with DNA. The yeast protein ADR1, a positive regulator of transcription of the gene ADH2, contains two finger domains in a region of the protein required for transcriptional activation. Nineteen independently isolated adr1 mutations induced by hydroxylamine were found at nine different amino-acid positions, seven of which are in the two finger domains. All four mutations that altered invariant cysteine or histidine residues led to an adr1 null phenotype. Only one other mutation caused an adr1 null phenotype. Thus, one finger domain is not sufficient for ADR1 activity. This provides the first evidence that, as is consistent with the proposed model, the invariant cysteine and histidine residues are essential for the formation of the finger structure.

Amino Acid Sequence↗
PubMedDate not supplied

[Distal post-traumatic edema--symptom of a sympathetic reflex dystrophy (Sudeck's disease)?].

The present paper describes various mechanisms, possibly being involved in the development of the posttraumatic, distally generalized edema. New ideas point to a special importance of the sympathetic vasoconstrictor system for this clinical phenomenon, since this system could induce an enhanced venoconstriction at the exit of the capillary bed, which would result in an edema producing diminished venous return. Since the distally generalized edema is an initially and very commonly occurring symptom of reflex sympathetic dystrophy (M. Sudeck), the observation of such an edema should lead one to look for further symptoms of this disorder, especially for the typical triad of autonomic (sympathetic), motor, and sensory disturbances.

Arm Injuries↗