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Biomedical subjects

H F Martin

Publications and source records attributed to H F Martin.

At least 37 records · Page 2Linked to original sources
PubMed1981

Spironolactone bodies. An immunoperoxidase study with biochemical correlation.

The present immunoperoxidase study attempted to localize aldosterone and cortisol in formalin-fixed paraffin-embedded adrenal glands or tumors. Apparently, steroid substances are solubilized during routine tissue processing, and the cytoplasm of adrenal cortical cells is not stained by either antialdosterone or anticortisol antibodies. However, spironolactone bodies react positively with antialdosterone antibody. The presence of aldosterone in the concentric laminations of spironolactone bodies supports the concept that spironolactone bodies are not artifacts. Furthermore, the fact that aldosterone does survive in spironolactone bodies suggests that it is bound in some unusual form. The spironolactone bodies are probably derived from endoplasmic reticulum, and the membranes of endoplasmic reticulum are considered capable of storing steroids. It is likely that during the formation of spironolactone bodies are probably derived from endoplasmic reticulum, and the membranes of endoplasmic reticulum are considered capable of storing steroids. It is likely that during the formation of spironolactone bodies, aldosterone or a few cortisol-like substances are trapped in these laminated concentric bodies.

Adrenal Glands↗
PubMed1980

Effects of spinal cord lesions on somatic evoked potentials altered by interactions between afferent inputs.

In cats anesthetized with alpha-chloralose, somatic evoked potentials (SEP) were recorded in response to electrical stimulation of surgically isolated peripheral nerves. Selected surgical lesions were made at T9-L1 spinal cord and were histologically verified. Two stimulus magnitudes were used to activate peripheral nerves, one only exciting the large fibers and another exciting the small fibers as well. Control SEPs were recorded in response to stimulation of both large and small fibers of the radial nerve. The later components (latencies greater than 40 msec) of this SEP were suppressed when evoked 100 msec after application of a conditioning stimulus (CS) to the large fibers of either peroneal nerve. Bilateral transection of the dorsal columns and spinocervical tracts eliminates these effects. Increasing the CS intensity to include small diameter fibers again resulted in reduction of the later components of the SEP. This interaction was largely eliminated if the transection was extended to include mid-lateral cord tracts. These results suggest that the SEP can be influenced by small fiber afferent activity conducted in mid-ventrolateral spinal cord in the absence of the dorsal columns and spinocervical tracts. Alterations in the forelimb-evoked SEP by a conditioning hindlimb stimulus is a sensitive indicator of spinal cord integrity. This method may be used to assess whether low spinal injury spares ventrolateral columns.

Afferent Pathways↗
PubMed1978

The effects of interaction between large and small diameter fiber systems on the somatosensory evoked potential.

The effect of interaction between large and small diameter fiber systems on the somatosensory evoked potential (SEP) was studied in anesthetized cats. Activation of large diameter fibers of the peroneal or radial nerves eliminates the late components of the SEP produced by stimulation of all fibers in the contralateral median or radial nerves. The inhibitory effects of a selective conditioning stimulus to the large diameter fibers of the peroneal nerve on the radial nerve evoked SEP was eliminated by bilateral transection of the dorsal column and spino-cervical tracts. However, interaction could still be obtained following transection when both large and small diameter fibers in the peroneal nerve were stimulated. The results of this study support the hypothesis that a correlation exists between activity in different fiber groups in afferent nerves, their conduction pathways through the cord, and the components of the cortical evoked potential.

Afferent Pathways↗
PubMed1975

Effects of activity in non-myelinated afferent fibres on the spinocervical tract.

Microelectrode recordings were made from axons of the spinocervical tract (SCT) in unanaesthetized decerebrate-spinal cats. Pure volleys in non-myelinated (C) cutaneous nerve fibres were obtained by DC-polarization block of conduction in the myelinated (A) fibres, and SCT cells were classified according to whether or not they were excited by C fibres. The effects of conditioning C responses in the SCT with A and C fibre input were examined, as were the effects of conditioning A fibre responses in the tract with C fibre inputs. The effects of stimulating descending systems in the cervical spinal cord on the C fibre-evoked responses of SCT cells were determined. SCT units with a slowly-adapting pressure-sensitive component in their receptive fields responded to cutaneous C fibres in addition to A fibres. Units which responded only to hair movement when the receptive field was stimulated mechanically were not excited by C fibres. Responses in SCT neurones produced by C fibres were profoundly inhibited by conditioning volleys in A fibres of both ipsilateral and contralateral cutaneous nerves and by activity in several descending systems. Conditioning with C fibres failed to affect the responses of SCT cells to either A or C fibres. It is concluded that cutaneous C fibres excite some SCT cells but have no other effect on transmission through this system. It is suggested that there are common inhibitory interneurones in the paths from descending systems and cutaneous A and C fibres to the excitatory input to SCT cells.

Animals↗
PubMed1975

An algorithm for the selection of proper group intervals for histograms representing clinical laboratory data.

Although numerous statistical methods are available, proper definitive technics to deal with the determination of normal values or ranges in clinical chemistry are unresolved and ill-defined. Initially, the ability to the analyst to define a mathematical function that can be used to best fit the random distribution of generated laboratory values still depends on proper grouping of the data. Herein is proposed a method for grouping data, in order to select the proper class interval to be used. Arbitrariness is removed and maximum information about the population being tested can be achieved. The concepts of "regrouping" and "sign reversal" are utilized, and the validity of this technic for constructing the "best" frequency histogram is verified by a general computer algorithm.

Clinical Laboratory Techniques↗