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Biomedical subjects

D C Quick

Publications and source records attributed to D C Quick.

At least 19 recordsLinked to original sources
PubMed1995

Arthroscopic posteromedial visualization of the knee.

Arthroscopic visualization of the posteromedial compartment of the knee via an anterolateral portal is not commonly practiced, yet it is relatively simple, has low morbidity, and is of diagnostic and therapeutic value. This prospective study evaluates posteromedial visualization of the knee joint in a series of 117 consecutive patients who underwent arthroscopy for diagnosis or treatment, or both, of 209 pathologic conditions. The technique was deemed simple to perform in 78% of patients. It was found to be more difficult in knees with degenerative joint disease. Posteromedial visualization was found to be essential for diagnosis or treatment in 4% of the diagnosed conditions, and helpful in an additional 13%. The technique was most useful for tears of the posterior horn of the medial meniscus, some of which were not detected by visualization from the anteromedial compartment alone. Visualization of the posteromedial compartment was deemed adequate in 89% of the patients, and there was no morbidity.

Adolescent↗
PubMed1995

Occult osseous lesions associated with anterior cruciate ligament tears.

Occult osseous lesions occurring with anterior cruciate ligament tears have been described only recently. Twenty patients with complete anterior cruciate ligament disruptions and evidence of occult osseous lesions on their preoperative magnetic resonance (MR) images were evaluated retrospectively at 24- to 73-months' followup to document the natural history and long-term effects of the lesions. Thirty-seven initial osseous signal abnormalities were documented on the MR images of 20 patients. All 20 patients had lesions in the posterolateral tibial plateau, and 13 had additional lesions in the lateral femoral condyle. Twenty-four of the 37 osseous lesions appeared resolved on followup MR images, and 13 had become sclerotic. Lesions of the lateral tibial plateau were especially likely to be sclerotic at followup. This study reaffirms the specificity of bone signal abnormalities of the posterolateral tibial plateau and lateral femoral condyle in association with complete anterior cruciate ligament tears. The data indicate that a proportion of anterior cruciate ligament patients will incur progressive articular cartilage abnormalities, although case-by-case predictions based on initial MR images would be unreliable.

Adult↗
PubMed1992

Use of a scanning laser three-dimensional digitizer to evaluate dimensional accuracy of dental impression materials.

A steel die was machined to represent a dental arch with teeth prepared for complete crowns. Impressions and casts were made from the die, and critical dimensions were measured by two methods--one using micrometers and the other a scanning laser three-dimensional (3-D) digitizer. The digitizer recorded measurements were more precise than the micrometer's and virtually eliminated operator error because the acquisition of data was automatic. The digitizer could also be useful for high-precision analyses of the dimensional accuracy of dental impression materials, but the cost and complexity of the instrument makes it less desirable for low-precision work.

Calibration↗
PubMed1988

Immuno-labelling for freeze-fracture: application to a cell surface attachment antigen.

The cell-surface attachment (CSAT) antigen was investigated by using a technique that combines freeze-fracture with thin-sectioning. Chick heart cells were labelled using colloidal gold secondary antibodies, then fractured and shadowed with platinum vapor. The cells were dehydrated and embedded with their gold labels and replicated surfaces still intact. Sectioning revealed gold particles superimposed with external (E) fracture faces. The gold was definitely not coincident with E face particles and did not appear to be associated with pits. Therefore, it can be concluded that the CSAT glycoproteins is not represented by an E face particle. Whether it may be seen as an E face pit, or is not visible at all in freeze-fracture, is still an open question.

Animals↗
PubMed1986

Acute lesion of the intrafusal muscle of muscle spindles: ultrastructural and electrophysiological consequences.

Experiments were performed to functionally separate the neural and muscular elements in muscle spindles. Cat muscle spindles were dissected free in vitro and were transected on both sides of the sensory nerve endings. This resulted in an acute lesion of the intrafusal muscle fibers but spared the sensory endings. Within 45 min, the intrafusal muscle fibers degenerated to the condition in which there were no myofilaments left in the sensory zone and the muscle fiber membrane had begun to disintegrate. During this degeneration period, and afterward, the sensory nerve fibers continued to fire action potentials. However, the postlesion discharge was usually more irregular than normal, and the mean rate of firing was often dramatically increased. In addition, multiplex frequencies of firing were often observed; that is, the interspike intervals were clustered around 2 or more modal values. Computer modeling of 2 action potential initiators competing for access to the same output line suggests that the multiplexing results from at least one of the competitors having a fraction of its spikes aborted. Overall, the results indicate that the nerve endings have an intrinsic capability to function as sensory receptors in the absence of a muscle substrate.

Animals↗
PubMed1985

Effect of intrafusal muscle mechanics on mammalian muscle spindle sensitivity.

Sensitivity differences between primary and secondary endings of mammalian muscle spindles under various conditions of stretch and fusimotor activation may be due to differences in their respective mechanoelectric transducers or to mechanical properties of the intrafusal muscle supporting those endings. This study of isolated cat muscle spindles examines the strain in individual intrafusal muscle fibers resulting from stretch and fusimotor stimulation. The degree of local stretch occurring at the sensory endings under these conditions was measured. The results support the hypothesis that the sensitivities of primary and secondary endings are quite similar. They are directly related to the local stretch of the underlying muscle which may be altered by changes in muscle stress and stiffness.

Animals↗
PubMed1984

Ultrastructure of the secretory epithelium, nerve fibers, and capillaries in the mouse sweat gland.

The ultrastructure of the mouse sweat gland was examined, in support of neurological studies of sweat glands and their relationships to the autonomic nervous system. It was found that the mouse sweat gland is similar to that of the rat and has only one type of secretory cell. Many nerve fibers are entwined with the secretory tubule and contain accumulations of round, clear vesicles, some microtubules, but apparently no neurofilaments. Cholinesterase is found in the clefts between nerve fibers and their ensheathing Schwann cells. The nerve fibers tend to run parallel with capillaries, but have no close association with either the capillaries or the secretory epithelium. Capillaries provide an abundant blood supply to the sweat gland and are fenestrated. The relationships between cellular elements of the sweat gland provide no direct evidence of the mechanisms involved in neurogenic sweating, although it seems likely that effector substances are diffusely distributed.

Animals↗
PubMed1984

Freeze-fracture of sensory nerve endings in cat muscle spindles.

Sensory nerve endings and intrafusal muscle fibres of cat muscle spindles were examined by freeze-fracture electron microscopy. The purpose of the study was to reveal intramembranous specializations that might be associated with the mechanosensory transducer system. Nerve ending membranes were found to contain high concentrations of intramembranous particles (greater than 7500 per micron2) in a range of sizes, but no localized aggregations or non-random arrangements were observed. Nerve ending membranes directly apposed to the surfaces of intrafusal muscle fibres did not appear to be strikingly different from non-interface membranes, although some differences in particle concentrations could be detected. The membranes of endings on nuclear bag and nuclear chain muscle fibres differed slightly in the numbers of particles and their distributions to protoplasmic or external fracture faces. It was concluded that intramembranous elements of the mechanoelectric transducer system may be dispersed over the whole surface of a sensory ending, rather than localized to smaller domains.

Animals↗
PubMed1984

Rodent eccrine sweat glands: a case of multiple efferent innervation.

The sweat territories of peripheral nerves to the hind-paw of the mouse were defined by a silastic impression mold method that allowed identification of every secreting sweat gland. It was found that the tibial, sural, saphenous and peroneal nerves all contribute to the innervation of foot pad sweat glands, and there is extensive overlapping of the sweat territories of the different peripheral nerves. Most sweat glands could be activated by electrical stimulation of axons in two or three peripheral nerves or in separate fascicles of one nerve. This was interpreted to indicate that these sweat glands receive multiple innervation and that sweat glands in the overlap regions between autonomous zones of adjacent cutaneous nerves can receive axons from each nerve. Partial denervation of sweat glands by section of one source of innervation did not prevent the gland from sweating during stimulation of intact axons to the gland, or after pilocarpine treatment. Totally denervated glands did not exhibit denervation hypersensitivity; they became unresponsive to pilocarpine, acetylcholine and adrenaline. These characteristics allowed detection of the appearance and progression of reinnervation (and reactivation) of denervated sweat glands by collateral branching from sudomotor fibers. Not only do these results increase our basic understanding of the anatomical relations between peripheral nerves and the sweat glands they innervate, but they also demonstrate that the mouse sweat gland provides a useful model system for studying neuropathology of the sympathetic nervous system.

Animals↗
PubMed1983

Stretch receptors in regenerated rat muscle.

Although muscle spindles are known to be present in regenerated muscles, it has not previously been reported whether they have any electrophysiological activity. In the present study, rat extensor digitorum longus muscles were traumatized so as to cause all muscle fibers to degenerate; the muscle nerves were either left intact to promote subsequent reinnervation or severed to impede reinnervation. After 2-4 months of regeneration, the muscles were subjected to stretch stimuli and sensory activity was recorded electrophysiologically. Many of the muscles contained stretch-sensitive units that behaved like muscle spindles, although the responses were often highly adaptive and somewhat erratic. In general, the responses from muscles with the nerve left intact were more normal than those from muscles in which the nerve had been severed. Silver staining of the same muscles showed that morphologically recognizable muscle spindles were present, but all were abnormal to varying degrees. These results demonstrate that regenerated muscles can regain some degree of sensory activity in addition to motor functions. The prospect of restored sensory activity may be critical in evaluating the efficacy of graft or transplant procedures for human muscles.

Animals↗
PubMed1982

Peripheral neurology of the diabetic Chinese hamster.

Genetically diabetic Chinese hamsters were examined anatomically and physiologically for evidence of peripheral neuropathy. Control animals were from non-diabetic strains. Conduction velocities in both motor and sensory components of the hind limb nerves were reduced 16-22% in diabetic compared with control hamsters. However, there was no reduction in nerve fibre diameters or other signs of abnormal morphology that could be correlated with these physiological effects. It is concluded that the diabetic hamster is useful as a model of human diabetic peripheral neuropathy, but the analogy is not precise. The neuropathy of moderately diabetic hamsters is generally less severe than human diabetic neuropathy in its clinical stages.

Animals↗
PubMed1981

Stretch-induced contraction of intrafusal muscle in cat muscle spindle.

Measurements of tension, stiffness, and sarcomere length of intrafusal muscle during ramp stretch of isolated muscle spindles have revealed a stretch-induced contraction of the bag1 fiber. This behavior can account for the very high sensitivity of primary endings to stretch as well as the enhanced sensitivity evoked by dynamic fusimotor stimulation.

Afferent Pathways↗
PubMed1978

Intra-axonal ferric ion-ferrocyanide staining of nodes of Ranvier and initial segments in central myelinated fibers.

Ferric ion and ferrocyanide were used to stain central nervous tissue from the spinal cords of rats following fixation in cacodylate-buffered aldehydes. At the nodes of Ranvier in myelinated fibers, the stain was localized primarily on the inner surface of the unmyelinated nodal axolemma, as had been reported previously for peripheral nodes. Unmyelinated initial segments of myelinated neurons were similarly stained, but the axon hillock, cell body and dendrites were not stained. Synapses also exhibited no staining. Details of stain localization and comparison of these results with other ultrastructural data suggest that the stain is specific for the node of Ranvier and the axon initial segment, and are consistent with the idea that the axolemma at these sites may be structurally different from the cell membrane in other regions of the neuron, including paranodal and internodal regions of the axon. The electron-dense substance underlying the cytoplasmic surface of the membrane at the nodes and initial segments may represent a substrate that serves to bind together membrane structures in specialized regions of the axolemma.

Animals↗
PubMed1978

Demyelination of Sternarchus electrocyte fibers by injection of diphtheria toxin.

Diphtheria toxin was injected into the electric organ of the gymnotid fish, Sternarchus albifrons. After 10 days, there was extensive demeylination of electrocyte fibers in the area of injection. Electron microscopy showed that paranodal loops of myelin do not separately cleanly from the axon, and remnants of the myelin loops may persist after demyelination of the internodes is nearly complete. The dense cytoplasmic undercoating of the nodal axolemma may disappear before the paranodal junctions are completely gone. Observations of demyelination of internodes between the elaborate, inexcitable nodes suggest that the presence of myelin may not be necessary for the maintenance of structural differentiation of this region of the axolemma. Use of diphtheria toxin to demyelinate Sternarchus electrocytes may provide a useful system for experimental neuropathological studies.

Animals↗
PubMed1977

Ferric ion, ferrocyanide, and inorganic phosphate as cytochemical reactants at peripheral nodes of Ranvier.

Ferric ion (Fe3+) and ferrocyanide (Fe(CN)64-) were used under a variety of conditions to stain nodes of Ranvier in mammalian peripheral nerves. Principal findings are: 1. Ferric ion will bind to the extracellular nodal gap substance if nerves are pretreated with a phosphate buffer; or, it will bind to the cytoplasmic surface of the nodal axolemma if pretreatment is with cacodylate or veronal--acetate buffer. 2. Ferrocyanide will bind to the inner surface of the nodal axolemma, where it may react with ferric ion to form a blue stain, or with an osmium compound to form a black stain. 3. Ferric ion and ferrocyanide are bound to nodes as colloidal precipitates, and may migrate away from their sites of formation. 4. Not all nodes in a single piece of tissue, or in a single fibre have identical staining properties. It is concluded that ferric ion, ferrocyanide, and inorganic phosphate are valuable as cytochemical reactants for peripheral nodes of Ranvier, but they must be used in carefully controlled experimental situations in order to avoid spurious results.

Animals↗